METHOD, APPARATUS AND SYSTEM FOR PROCESSING VERY-HIGH-SPEED RANDOM ACCESS

Abstract

A method, an apparatus and a system process very-high-speed random access. The method includes: selecting a ZC sequence group according to a cell type and a first cyclic shift parameter Ncs, and setting N detection windows for each ZC sequence in the ZC sequence group, where N≥5; sending the cell type, a second Ncs, and the ZC sequence group to a UE; receiving a random access signal sent by the UE, and obtaining the random access sequence from the random access signal; performing correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detecting a valid peak value in the N detection windows of each ZC sequence, and determining an estimated value of an RTD according to the valid peak value, so that a UE in a very-high-speed scenario can normally access a network, thereby improving network access performance.

Description

TECHNICAL FIELD

The present disclosure relates to the field of mobile communications systems, and in particular, to a method, an apparatus and a system for processing very-high-speed random access.

BACKGROUND

In a Long Term Evolution (Long Term Evolution, LTE) system, a random access channel (Random Access Channel, RACH) is mainly used for initial access of a user equipment (User Equipment, UE) and does not carry any user data. A signal sent by a UE on an RACH is a preamble (Preamble) sequence, where the preamble sequence is a Zadoff-Chu sequence (Zadoff-Chu sequence, ZC sequence). In the prior art, a Preamble may include two parts which are a section of cyclic prefix (Cyclic Prefix, CP) with a length of T_CP and a section of access sequence (Sequence, SEQ) with a length of T_SEQ. In addition, parameter settings of different formats of Preambles may be matched to different cell radii, as shown in Table 1:

TABLE 1
Preamble
sequence			Maximum cell radius
format No.	TCP	TSEQ	(km)
0	3168 · Ts	24576 · Ts	Approximately 14.6
1	21024 · Ts	24576 · Ts	Approximately 77.3
2	6240 · Ts	2 · 24576 · Ts	Approximately 29.6
3	21024 · Ts	2 · 24576 · Ts	Approximately 100
4	448 · Ts	4096 · Ts	Approximately 1.4

where T_s is a basic time unit in an LTE protocol, and T_s=1/(15000×2048)s.

In the prior art, a 0-15 km/h low speed scenario is optimized by the LTE system, so that relatively high performance is still achieved in a 15-120 km/h high speed movement scenario, and connection can still be maintained in a 120-350 km/h high speed movement scenario. In an existing LTE protocol, two cell configurations, an unrestricted cell configuration and a restricted cell configuration, are supported, where an unrestricted cell is applied to a low frequency deviation scenario (for example, the frequency deviation is less than 600 Hz), and a restricted cell is applied to a high frequency deviation scenario (for example, the frequency deviation is greater than 600 Hz). With regard to a restricted cell, when a random access signal sent by a UE uses a ZC sequence (Zadoff-Chu Sequence) as a random access sequence, an evolved base station (evolved Node B, NodeB or eNB or e-NodeB) can ensure correct detection of a round trip delay (Round Trip Delay, RTD) within a frequency deviation range

$\left[-\frac{3*\Delta f_{\mathrm{RA}}}{2},\frac{3*\Delta f_{\mathrm{RA}}}{2}\right],$

where Δf_RA represents a subcarrier spacing of the random access channel, and the UE adjusts a timing advance (Timing Advance, TA) according to the RTD, thereby adjusting message sending timing and ensuring that the UE can normally access a network.

With the development of communications technologies and increased communications requirements of users, operators come up with requirements for coverage in very-high-speed movement scenarios and high frequency band high-speed railway scenarios. In the two types of scenarios, a frequency deviation of the random access signal is larger, which is

$\left[-\frac{W*\Delta f_{\mathrm{RA}}}{2},\frac{W*\Delta f_{\mathrm{RA}}}{2}\right],$

where W≥5. It is very difficult for an eNB to ensure correctness of RTD detection under a high frequency deviation. As a result, it is very difficult to ensure that a UE normally accesses a network, which affects access performance of the network.

SUMMARY

Embodiments of the present invention provide a method, an apparatus and a system for processing very-high-speed random access, so that a user equipment in a very-high-speed movement scenario can normally access a network, so as to improve access performance of the network.

One aspect of the present invention provides a method for processing very-high-speed random access, including: selecting a ZC sequence group according to a cell type and a first cyclic shift parameter Ncs, and setting N detection windows for each ZC sequence in the ZC sequence group, where N≥5; sending the cell type, a second Ncs, and the ZC sequence group to a user equipment UE, so that the UE selects a random access sequence from the ZC sequence group; receiving a random access signal sent by the UE, and obtaining the random access sequence from the random access signal; and performing correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detecting a valid peak value in the N detection windows of each ZC sequence, and determining an estimated value of a round trip delay RTD according to the valid peak value.

Another aspect of the present invention provides an apparatus for processing very-high-speed random access, including: a selecting unit, configured to select a ZC sequence group according to a cell type and a first cyclic shift parameter Ncs; a setting unit, configured to set N detection windows for each ZC sequence in the ZC sequence group selected by the selecting unit, where N≥5; a sending unit, configured to send the cell type, a second Ncs, and the ZC sequence group selected by the selecting unit to a user equipment UE, so that the UE selects a random access sequence from the ZC sequence group; a receiving unit, configured to receive a random access signal sent by the UE and obtain the random access sequence from the random access signal; and a detecting unit, configured to perform correlation processing on the random access sequence obtained by the receiving unit with each ZC sequence in the ZC sequence group, detect a valid peak value in the N detection windows set by the setting unit for each ZC sequence, and determine an estimated value of a round trip delay RTD according to the valid peak value.

It can be known from the above technical solutions that, by using the embodiments of the present invention, a ZC sequence group is selected according to a cell type and a first cyclic shift parameter Ncs, N detection windows are set for each ZC sequence in the ZC sequence group, where N≥5, and an estimated value of the RTD is determined according to a valid peak value detected in the N detection windows of each ZC sequence. In this way, a problem that an RTD of a random access signal cannot be correctly detected in a very-high-speed scenario is solved, it is ensured that a user equipment moving at a very high speed can correctly adjust a TA value according to a detected RTD, and therefore message sending timing is correctly adjusted, so that the user equipment in a very-high-speed scenario can normally access a network, thereby improving access performance of the network.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show some embodiments of the present invention, and persons of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

FIG. 1 is a flowchart of a method for processing very-high-speed random access according to an embodiment of the present invention;

FIG. 2 is a flowchart of another method for processing very-high-speed random access according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating changing of a valid peak value with frequency deviations in detection windows according to an embodiment of the present invention;

FIG. 4 is a flowchart of another method for processing very-high-speed random access according to an embodiment of the present invention;

FIG. 5 is a flowchart of still another method for processing very-high-speed random access according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a position relation between a valid peak value and an overlap between detection windows according to an embodiment of the present invention; and

FIG. 7 is a schematic structural diagram of an apparatus for processing very-high-speed random access according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

As shown in FIG. 1, a method for processing very-high-speed random access according to an embodiment of the present invention is specifically described as follows:

101. Select a ZC sequence group according to a cell type and a first cyclic shift (cyclic shift) parameter Ncs, and set N detection windows for each ZC sequence in the ZC sequence group, where N≥5.

The cell type includes an unrestricted cell and a restricted cell, and may be configured according to an application scenario. For example, the cell type may be configured to unrestricted cell for a low speed scenario, and configured to restricted cell for a high speed scenario.

The first Ncs is used to represent a cell coverage range, that is, a cell coverage radius. The larger the first Ncs is, the larger the cell coverage range is. Configuration of the first Ncs belongs to the prior art, and therefore is not described herein any further.

The ZC sequence group includes M ZC root sequences, where M<64. In the 3GPP TS 36.211 protocol, 838 ZC root sequences are defined totally. The ZC sequence group may include 64 ZC root sequences at most.

The setting N detection windows for each ZC sequence in the ZC sequence group may specifically include the following steps.

The du_HT value of the i^th ZC sequence refers to a shift of a mirror image peak in a power delay profile PDP of the i^th ZC sequence relative to an RTD when a frequency deviation is

$\pm \frac{1}{T_{\mathrm{SEQ}}},$

where T_SEQ is a time duration occupied by the i^th ZC sequence and a value of i is any integer in [1, M].

The du_HT values may be obtained by using a manner A1 or a manner A2.

In the manner A1, the value is obtained by calculation according to Formula 1, which is detailed as follows:

$\begin{array}{cc}{\mathrm{du}}_{\mathrm{HT}}=\{\begin{array}{cc}-p& 0\le p<N_{\mathrm{ZC}}/2\\ N_{\mathrm{ZC}}-p& \mathrm{else}\end{array}& \left(\mathrm{Formula}1\right)\end{array}$

where p is a minimum non-negative integer when (p·u) mod N_zc=1, u is a physical root sequence number of the ZC sequence, and Nzc is a length of the ZC sequence, where the Nzc may be 839 or 139. When Nzc is a fixed value, P is decided by a value of u. Then, according to the above Formula 1, the du_HT is decided by the value of u.

For example, if Nzc=839, when the physical root sequence number u=3, (p·3)mod 839=1, p=280, and du_HT=−280 can be obtained according to Formula 1; when the physical root sequence number u=836, (p·836)mod 839=1, p=1119, and du_HT=280 can be obtained according to Formula 1.

In the manner A2, the value is obtained by querying Table 2 or Table 3.

Table 2 lists du_HT(u) values when Nzc=839, where u=1, . . . , 419. When u=42Q, . . . , 838, du_HT(u) values can be obtained using a formula du_HT(Nzc−u)=−du_HT(u), u=1, . . . , 419. For example, when the physical root sequence number u=3, it can be obtained by querying the table that du_HT=−280; when u=450, Nzc−u=839−450=389. Let u′=389, and then du_HT(Nzc−u′)=−du_HT(u′)=−du_HT(389)=110.

TABLE 2
Values of duHT when NZC = 839
u   duHT
1   −1
2   419
3   −280
4   −210
5   −168
6   −140
7   −120
8   −105
9   −373
10  −84
11  305
12  −70
13  129
14  −60
15  −56
16  367
17  148
18  233
19  −265
20  −42
21  −40
22  −267
23  −73
24  −35
25  302
26  −355
27  −404
28  −30
29  405
30  −28
31  −406
32  −236
33  −178
34  74
35  −24
36  −303
37  68
38  287
39  43
40  −21
41  266
42  −20
43  39
44  286
45  261
46  383
47  357
48  402
49  −137
50  151
51  329
52  242
53  −95
54  −202
55  61
56  −15
57  −368
58  −217
59  −128
60  −14
61  55
62  −203
63  −293
64  −118
65  −142
66  −89
67  288
68  37
69  −304
70  −12
71  −130
72  268
73  −23
74  34
75  −179
76  −276
77  −316
78  −398
79  −308
80  409
81  145
82  133
83  374
84  −10
85  −306
86  −400
87  135
88  143
89  −66
90  −289
91  378
92  −228
93  −415
94  −241
95  −53
96  201
97  −173
98  351
99  −339
100 −344
101 −108
102 −255
103 −391
104 121
105 −8
106 372
107 345
108 −101
109 254
110 −389
111 −257
112 412
113 −297
114 −184
115 321
116 311
117 294
118 −64
119 141
120 −7
121 104
122 −392
123 −191
124 318
125 396
126 273
127 218
128 −59
129 13
130 −71
131 −269
132 375
133 82
134 144
135 87
136 −401
137 −49
138 −152
139 169
140 −6
141 119
142 −65
143 88
144 134
145 81
146 408
147 234
148 17
149 366
150 330
151 50
152 −138
153 −170
154 −158
155 −249
156 −199
157 171
158 −154
159 248
160 −215
161 −370
162 −347
163 175
164 −353
165 300
166 187
167 211
168 −5
169 139
170 −153
171 157
172 −200
173 −97
174 −352
175 163
176 −348
177 237
178 −33
179 −75
180 275
181 394
182 189
183 298
184 −114
185 −322
186 212
187 166
188 299
189 182
190 393
191 −123
192 −319
193 −313
194 333
195 −327
196 −244
197 362
198 250
199 −156
200 −172
201 96
202 −54
203 −62
204 292
205 221
206 224
207 −381
208 −359
209 281
210 −4
211 167
212 186
213 −323
214 −247
215 −160
216 369
217 −58
218 127
219 272
220 225
221 205
222 291
223 −380
224 206
225 220
226 271
227 −377
228 −92
229 414
230 −259
231 −385
232 −264
233 18
234 147
235 407
236 −32
237 177
238 −349
239 337
240 416
241 −94
242 52
243 328
244 −196
245 −363
246 324
247 −214
248 159
249 −155
250 198
251 361
252 −283
253 −388
254 109
255 −102
256 390
257 −111
258 −413
259 −230
260 384
261 45
262 285
263 386
264 −232
265 −19
266 41
267 −22
268 72
269 −131
270 −376
271 226
272 219
273 126
274 395
275 180
276 −76
277 315
278 −335
279 −418
280 −3
281 209
282 −360
283 −252
284 387
285 262
286 44
287 38
288 67
289 −90
290 −379
291 222
292 204
293 −63
294 117
295 310
296 −411
297 −113
298 183
299 188
300 165
301 −354
302 25
303 −36
304 −69
305 11
306 −85
307 399
308 −79
309 −410
310 295
311 116
312 320
313 −193
314 −334
315 277
316 −77
317 397
318 124
319 −192
320 312
321 115
322 −185
323 −213
324 246
325 −364
326 −332
327 −195
328 243
329 51
330 150
331 365
332 −326
333 194
334 −314
335 −278
336 417
337 239
338 −350
339 −99
340 343
341 −342
342 −341
343 340
344 −100
345 107
346 371
347 −162
348 −176
349 −238
350 −338
351 98
352 −174
353 −164
354 −301
355 −26
356 403
357 47
358 382
359 −208
360 −282
361 251
362 197
363 −245
364 −325
365 331
366 149
367 16
368 −57
369 216
370 −161
371 346
372 106
373 −9
374 83
375 132
376 −270
377 −227
378 91
379 −290
380 −223
381 −207
382 358
383 46
384 260
385 −231
386 263
387 284
388 −253
389 −110
390 256
391 −103
392 −122
393 190
394 181
395 274
396 125
397 317
398 −78
399 307
400 −86
401 −136
402 48
403 356
404 −27
405 29
406 −31
407 235
408 146
409 80
410 −309
411 −296
412 112
413 −258
414 229
415 −93
416 240
417 336
418 −279
419 2

Table 3 lists du_HT(u) values when Nzc=139, where u=1, . . . , 69 When u=70, . . . , 138, du_HT(u) values can be obtained using a formula du_HT(Nzc−u)=−du_HT(u), u=1, . . . , 69.

TABLE 3
Values of duHT when NZC = 139
u  duHT
1  −1
2  69
3  46
4  −35
5  −28
6  23
7  −20
8  52
9  −31
10 −14
11 −38
12 −58
13 32
14 −10
15 37
16 26
17 49
18 54
19 −22
20 −7
21 −53
22 −19
23 6
24 −29
25 50
26 16
27 36
28 −5
29 −24
30 −51
31 −9
32 13
33 −59
34 −45
35 −4
36 27
37 15
38 −11
39 57
40 66
41 61
42 43
43 42
44 60
45 −34
46 3
47 68
48 55
49 17
50 25
51 −30
52 8
53 −21
54 18
55 48
56 67
57 39
58 −12
59 −33
60 44
61 41
62 65
63 −64
64 −63
65 62
66 40
67 56
68 47
69 2

Then, determine start positions of the N detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence.

The number N of detection windows may be preset inside a base station according to a frequency deviation range, or may be dynamically configured to the base station on an operation and maintenance console.

For example, as an embodiment, when the frequency deviation range is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right],$

the number of detection windows of the ZC sequence may be configured to five, and, however, the number of detection windows of the ZC sequence may also be configured to more than five. When the frequency deviation range is

$\left[-\frac{W*\Delta f_{\mathrm{RA}}}{2},\frac{W*\Delta f_{\mathrm{RA}}}{2}\right],$

and W>5, the number N of detection windows of the ZC sequence may be configured to W, and the number N of detection windows of the ZC sequence may also be configured to more than W.

Finally, set the N detection windows of the i^th ZC sequence according to start positions of the N detection windows of the i^th ZC sequence and a preset size of a detection window.

The size of a detection window may be preset according to the cell radius, and the window size is no less than an RTD corresponding to the cell radius. For example, based on the RTD corresponding to the cell radius, the detection window may be expanded according to a multipath delay.

102. Send the cell type, a second Ncs, and the ZC sequence group to a user equipment UE, so that the UE selects a random access sequence from the ZC sequence group.

The second Ncs refers to an index value that can ensure that the UE uses the ZC root sequence in the ZC sequence group as a random access sequence. For example, two configuration manners in the following may be used.

Manner 1: When the cell type is configured to unrestricted cell (or low-speed cell), the second Ncs index is 0.

Manner 2: When the cell type is configured to restricted cell (or high-speed cell), the second Ncs index is 14.

In manner 2, the second Ncs index is not limited to 14, and may be any other index that enables the UE to use a ZC sequence which does not shift cyclically as the random access sequence, so as to reduce an overlap probability of the N detection windows of the ZC sequence. The second Ncs may be set inside the base station, or determined according to the configured cell type inside the base station, or obtained by querying a table, and is sent to the UE in a system message.

It should be noted that the first Ncs in step 101 is set according to the cell coverage range, and reflects the cell coverage radius. The second Ncs in step 102 is only used to be sent to the UE, so that the UE uses the ZC root sequence in the ZC sequence group as the random access sequence rather than uses a ZC sequence that shifts cyclically as the random access sequence, which can reduce the overlap probability of the N detection windows. If the index value of the first Ncs in step 101 meets a condition of enabling the UE to use the ZC sequence which does not shift cyclically as the random access sequence, the first Ncs and the second Ncs may be the same.

Partial ZC sequences in the ZC sequence group are used for contention access, and partial ZC sequences are used for contention-free access. For contention access, the UE randomly selects one ZC sequence from ZC sequences used for contention access in the ZC sequence group as the random access sequence. For contention-free access, the base station indicates to the UE which ZC sequence in the ZC sequence group is to be used as the random access sequence.

103. Receive a random access signal sent by the UE, and obtain the random access sequence from the random access signal.

104. Perform correlation processing (correlation) on the random access sequence with each ZC sequence in the ZC sequence group, detect a valid peak value in the N detection windows of each ZC sequence, and determine an estimated value of a round trip delay RTD according to the valid peak value.

The valid peak value is obtained by determining a maximum peak value in each detection window and a position of the maximum peak value in each detection window, and is specifically described as follows:

When only one maximum peak value is greater than a detection threshold, the peak value greater than the detection threshold is selected as the valid peak value. The valid peak value may also be called a primary peak value.

When two or more than two maximum peak values are greater than the detection threshold, whether absolute positions of the two maximum peak values overlap is determined. If the absolute positions do not overlap, the two maximum peak values are selected as valid peak values, where a greater valid peak value in the two valid peak values is called a primary peak value and a smaller valid peak value in the two valid peak values is called a secondary peak value. If the absolute positions overlap, the two maximum peak values are the same peak value and used as the primary peak value, and a maximum peak value greater than the detection threshold detected in a detection window corresponding to a spacing of the frequency deviation of the detection window in which the primary peak value is located plus 1 or the frequency deviation minus 1 RACH subcarriers is a secondary peak value.

The detection threshold may be set according to a false-alarm performance requirement under discontinuous transmission.

The estimated value of the RTD is a deviation of the valid peak value relative to a start position of a detection window in which the valid peak value is located. If the start position of the detection window in which the valid peak value is located is shifted based on the start position determined according to the du_HT value of the ZC sequence, the estimated value of the RTD may be obtained according to a deviation value of the valid peak value relative to the start position of the detection window in which the valid peak value is located, a shift direction and shift sampling points, which is specifically described as follows:

Assuming that the start position of the detection window in which the valid peak value is located shifts left by preset sampling points, the estimated value of the RTD is a deviation value of the valid peak value relative to the start position of the detection window in which the valid peak value is located minus the number of the preset sampling points. Assuming that the start position of the detection window in which the valid peak value is located shifts right by the preset sampling points, the estimated value of the RTD is a deviation value of the valid peak value relative to the start position of the detection window in which the valid peak value is located plus the number of the preset sampling points.

By using the method for processing very-high-speed random access provided by the foregoing embodiment, a problem that an RTD of a random access signal cannot be correctly detected in a very-high-speed scenario is solved, it is ensured that a user equipment moving at a very high speed can correctly adjust a TA value according to a detected RTD, and therefore message sending timing is correctly adjusted, so that the user equipment in a very-high-speed scenario can normally access a network, thereby improving access performance of the network.

As shown in FIG. 2, a method for processing very-high-speed random access according to an embodiment of the present invention, where N detection windows are set for each ZC sequence in a ZC sequence group when a frequency deviation range of very-high-speed random access is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right],$

where N=5, is specifically described as follows:

201. Select a ZC sequence group according to a cell type and a first Ncs.

For relevant descriptions of the cell type and the first Ncs as well as the ZC sequence group, refer to step 101.

The selecting a ZC sequence group according to a cell type and a first Ncs is specifically described as follows:

B1. Select the ZC sequence group according to the cell type and the first Ncs.

B2. Determine whether a du_HT value of each ZC sequence in the ZC sequence group meets a condition

${\mathrm{du}}_{\mathrm{HT}}\in \left[\mathrm{Ncs},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{4}\right]\bigcup \hspace{1em}[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{4},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{3}]\bigcup [\frac{\mathrm{Nzc}+\mathrm{Ncs}}{3},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{2}],$

where Nzc is a length of each ZC sequence, and Ncs refers to the first Ncs;

if the du_HT value of at least one ZC sequence in the ZC sequence group does not meet the condition, return to step B 1; and

if du_HT values of the ZC sequences in the ZC sequence group all meet the condition, send the ZC sequence group to a user equipment;

where, for an obtaining manner of the du_HT value, reference may be made to relevant descriptions in step 101.

It should be noted that, when the du_HT value of each ZC sequence in the selected ZC sequence group meets the condition

${\mathrm{du}}_{\mathrm{HT}}\in \left[\mathrm{Ncs},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{4}\right]\bigcup \hspace{1em}\left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{4},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{3}\right]\bigcup \left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{3},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{2}\right],$

the five detection windows set according to the du_HT value of each ZC sequence do not overlap, which improves correctness of RTD estimation.

For example, assuming that the cell type is restricted cell, the first Ncs set according to a cell radius is 15, the selected ZC sequence group includes 64 ZC sequences, and a length of a ZC sequence is 839, a method for selecting the ZC sequence group according to the cell type and the first Ncs is described with an example as follows:

First, select logical root sequence numbers of the 64 ZC sequences according to the cell type and the first Ncs.

Table 4 is a mapping table between Ncs values and logical root sequence numbers of a restricted cell. The first column includes two Ncs values of 15, where a first logical root sequence number corresponding to the first Ncs of 15 is 24, and a second logical root sequence number corresponding to the second Ncs of 15 is 819. Therefore, available logical root sequence numbers are [24, 819] when the first Ncs is 15.

TABLE 4
Mapping table between Ncs values and logical
root sequence numbers of a restricted cell
NCS value (restricted cell) Logical root sequence number
—                           0-23
15                          24-29
18                          30-35
22                          36-41
26                          42-51
32                          52-63
38                          64-75
46                          76-89
55                          90-115
68                          116-135
82                          136-167
100                         168-203
128                         204-263
158                         264-327
202                         328-383
237                         384-455
237                         456-513
202                         514-561
158                         562-629
128                         630-659
100                         660-707
82                          708-729
68                          730-751
55                          752-765
46                          766-777
38                          778-789
32                          790-795
26                          796-803
22                          804-809
18                          810-815
15                          816-819
—                           820-837

Then, obtain the physical root sequence numbers of the 64 ZC sequences according to a mapping table between the logical root sequence numbers and the physical root sequence numbers.

Table 5 provides the mapping between partial logical root sequence numbers and partial physical root sequence numbers.

TABLE 5
Mapping table between logical root sequence numbers and physical root sequence numbers
Logical root sequence number
(Logical root sequence number) Physical root sequence number (Physical root sequence number u)
0-23                           129, 710, 140, 699, 120, 719, 210, 629, 168, 671, 84, 755, 105, 734, 93,
                               746, 70, 769, 60, 779
                               2, 837, 1, 838
24-29                          56, 783, 112, 727, 148, 691
30-35                          80, 759, 42, 797, 40, 799
36-41                          35, 804, 73, 766, 146, 693
42-51                          31, 808, 28, 811, 30, 809, 27, 812, 29, 810
52-63                          24, 815, 48, 791, 68, 771, 74, 765, 178, 661, 136, 703
64-75                          86, 753, 78, 761, 43, 796, 39, 800, 20, 819, 21, 818
76-89                          95, 744, 202, 637, 190, 649, 181, 658, 137, 702, 125, 714, 151, 688
90-115                         217, 622, 128, 711, 142, 697, 122, 717, 203, 636, 118, 721, 110, 729,
                               89, 750, 103, 736, 61, 778, 55, 784, 15, 824, 14, 825
116-135                        12, 827, 23, 816, 34, 805, 37, 802, 46, 793, 207, 632, 179, 660, 145,
                               694, 130, 709, 223, 616
136-167                        228, 611, 227, 612, 132, 707, 133, 706, 143, 696, 135, 704, 161, 678,
                               201, 638, 173, 666, 106, 733, 83, 756, 91, 748, 66, 773, 53, 786, 10,
                               829, 9, 830
168-203                        7, 832, 8, 831, 16, 823, 47, 792, 64, 775, 57, 782, 104, 735, 101, 738,
                               108, 731, 208, 631, 184, 655, 197, 642, 191, 648, 121, 718, 141, 698,
                               149, 690, 216, 623, 218, 621
204-263                        152, 687, 144, 695, 134, 705, 138, 701, 199, 640, 162, 677, 176, 663,
                               119, 720, 158, 681, 164, 675, 174, 665, 171, 668, 170, 669, 87, 752,
                               169, 670, 88, 751, 107, 732, 81, 758, 82, 757, 100, 739, 98, 741, 71,
                               768, 59, 780, 65, 774, 50, 789, 49, 790, 26, 813, 17, 822, 13, 826, 6,
                               833
264-327                        5, 834, 33, 806, 51, 788, 75, 764, 99, 740, 96, 743, 97, 742, 166, 673,
                               172, 667, 175, 664, 187, 652, 163, 676, 185, 654, 200, 639, 114, 725,
                               189, 650, 115, 724, 194, 645, 195, 644, 192, 647, 182, 657, 157, 682,
                               156, 683, 211, 628, 154, 685, 123, 716, 139, 700, 212, 627, 153, 686,
                               213, 626, 215, 624, 150, 689
328-383                        225, 614, 224, 615, 221, 618, 220, 619, 127, 712, 147, 692, 124, 715,
                               193, 646, 205, 634, 206, 633, 116, 723, 160, 679, 186, 653, 167, 672,
                               79, 760, 85, 754, 77, 762, 92, 747, 58, 781, 62, 777, 69, 770, 54, 785,
                               36, 803, 32, 807, 25, 814, 18, 821, 11, 828, 4, 835
384-455                        3, 836, 19, 820, 22, 817, 41, 798, 38, 801, 44, 795, 52, 787, 45, 794, 63,
                               776, 67, 772, 72
                               767, 76, 763, 94, 745, 102, 737, 90, 749, 109, 730, 165, 674, 111, 728,
                               209, 630, 204, 635, 117, 722, 188, 651, 159, 680, 198, 641, 113, 726,
                               183, 656, 180, 659, 177, 662, 196, 643, 155, 684, 214, 625, 126, 713,
                               131, 708, 219, 620, 222, 617, 226, 613
456-513                        230, 609, 232, 607, 262, 577, 252, 587, 418, 421, 416, 423, 413, 426,
                               411, 428, 376, 463, 395, 444, 283, 556, 285, 554, 379, 460, 390, 449,
                               363, 476, 384, 455, 388, 451, 386, 453, 361, 478, 387, 452, 360, 479,
                               310, 529, 354, 485, 328, 511, 315, 524, 337, 502, 349, 490, 335, 504,
                               324, 515
. . .                          . . .

If the selected logical root sequence number is 384, the physical root sequence numbers of the 64 ZC sequences may be obtained according to the mapping between the logical root sequence numbers and the physical root sequence numbers in Table 5 as follows: 3, 836, 19, 820, 22, 817, 41, 798, 38, 801, 44, 795, 52, 787, 45, 794, 63, 776, 67, 772, 72, 767, 76, 763, 94, 745, 102, 737, 90, 749, 109, 730, 165, 674, 111, 728, 209, 630, 204, 635, 117, 722, 188, 651, 159, 680, 198, 641, 113, 726, 183, 656, 180, 659, 177, 662, 196, 643, 155, 684, 214, 625, 126, 713.

Then, obtain du_HT values of the 64 ZC sequences.

According to relevant descriptions and obtaining method of du_HT in step 101, it may be obtained that: when the physical root sequence number u=3, du_HT=−280; when the physical root sequence number u=836, du_HT=280; and when the physical root sequence number u=19, du_HT=265, . . . .

Finally, determine whether the du_HT values of the selected 64 ZC sequences all meet a condition

${\mathrm{du}}_{\mathrm{HT}}\in \left[\mathrm{Ncs},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{4}\right]\bigcup \hspace{1em}\left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{4},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{3}\right]\bigcup \left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{3},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{2}\right].$

If the condition is not met, reselect the ZC sequence group.

|du_HT|∈[15,206]∪[213,274]∪[284,412] is worked out by calculating according to the first Ncs and Nzc. In the selected 64 ZC sequences, when the physical root sequence numbers are 3 and 836, the du_HT values do not meet the du_HT value condition. Therefore, reselect 64 ZC sequences according to the selecting step of the ZC sequence group.

Assuming that the physical root sequence numbers of the reselected 64 ZC sequences are 56, 783, 112, 727, 148, 691, 80, 759, 42, 797, 40, 799, 35, 804, 73, 766, 146, 693, 31, 808, 28, 811, 30, 809, 29, 810, 27, 812, 24, 815, 48, 791, 68, 771, 74, 765, 178, 661, 136, 703, 86, 753, 78, 761, 43, 796, 39, 800, 20, 819, 21, 818, 95, 744, 202, 637, 190, 649, 181, 658, 137, 702, 125, 714, obtain du_HT values and determine that the du_HT values of the reselected 64 ZC sequences meet the du_HT condition.

202. Set N detection windows for each ZC sequence in the ZC sequence group, where N=5.

When the ZC sequence group includes M ZC sequences, the setting N detection windows for each ZC sequence in the ZC sequence group, where N=5, is specifically described as follows:

C1. Obtain a du_HT value of an i^th ZC sequence in the ZC sequence group.

The du_HT value of the i^th ZC sequence refers to a shift of a mirror image peak in a power delay profile PDP of the i^th ZC sequence relative to the RTD when a frequency deviation is

$\pm \frac{1}{T_{\mathrm{SEQ}}},$

where T_SEQ is a time duration occupied by the i^th ZC sequence and a value of i is any integer in [1, M].

C2. Set five detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence.

First, obtain start positions of the five detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence.

The five detection windows of the i^th ZC sequence are a detection window {circle around (1)}, a detection window {circle around (2)}, a detection window {circle around (3)}, a detection window {circle around (4)} and a detection window {circle around (5)}, respectively. The five detection windows {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)} and {circle around (5)} respectively correspond to frequency deviations 0, −Δf_RA, +Δf_RA, −2Δf_RA and +2f_RA. The details are as follows:

a start position of the detection window {circle around (1)} is 0;

a start position of the detection window {circle around (2)} is mod(du_HT, Nzc);

a start position of the detection window {circle around (3)} is mod(−du_HT, Nzc);

a start position of the detection window {circle around (4)} is mod(2*HT, Nzc); and

a start position of the detection window {circle around (5)} is mod(−2*du_HT, Nzc);

where mod(du_HT, Nzc) means du_HT mod Nzc, Nzc is a length of the i^th ZC sequence, and for an obtaining manner of the du_HT value, reference may be made to step 101.

Then, set the five detection windows of the i^th ZC sequence according to the start positions of the five detection windows and a preset size of a detection window.

The size of the detection window is consistent with relevant descriptions in step 101. The start position of the detection window may be shifted according to preset sampling points, so as to adapt to earlier or later transmission of a random access signal by a UE.

203. Send the cell type, a second Ncs, and the ZC sequence group to a UE, so that the UE selects a random access sequence from the ZC sequence group.

For relevant descriptions of the second Ncs, refer to step 102.

204. Receive a random access signal sent by the UE, and obtain the random access sequence from the random access signal.

205. Perform correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detect a valid peak value in the five detection windows of each ZC sequence, and determine an estimated value of an RTD according to the valid peak value.

The valid peak value and the estimated value of the RTD are consistent with relevant descriptions in step 104.

The determining the RTD according to the valid peak value may be obtained by using two methods as follows:

Method (1): Directly obtain the estimated value of the RTD according to a deviation of a primary peak value relative to a start position of a primary peak value detection window.

Method (2): Select and merge data of at least two detection windows according to a preset principle to obtain a new valid peak value, and estimate the RTD.

In the method (2), according to the preset principle, detection windows at two sides of the primary peak value may be merged, or a detection window in which the primary peak value is located and a detection window in which a secondary peak value is located may be merged, or all the detection windows may be merged. Since the detection windows are merged, a detection threshold of the valid peak value is increased accordingly. Therefore, a new valid peak value may be obtained, and the RTD may be estimated according to the obtained new effective value.

206. Estimate a frequency deviation according to a detection window in which the valid peak value is located.

An estimated value of the frequency deviation is used for rectifying a deviation of an uplink signal of the UE and demodulating a Message 3 message sent by the UE. The Message 3 carries an identifier of the UE.

FIG. 3 is a schematic diagram illustrating changing of a valid peak value with frequency deviations in detection windows. The estimating a frequency deviation according to a detection window in which the valid peak value is located specifically includes three cases as follows:

Case 1: When two valid peak values exist, if a primary peak value is located in a detection window {circle around (1)} and a secondary peak value is located in a detection window {circle around (3)}, a frequency deviation of an uplink signal of a UE may be estimated to be a value within a range of 0 to −½f_RA according to the schematic diagram of the peak values in each window changing with the frequency deviation as shown in FIG. 3. If a maximum peak value is in the detection window {circle around (3)} and a second maximum peak value is in a detection window {circle around (5)}, the frequency deviation of the uplink signal of the UE is estimated to be a value within a range of Δf_RA to 3/2Δf_RA; and so on.

Case 2: If two valid peak values exist and are close, where one is located in the detection window {circle around (1)} and the other is located in the detection window {circle around (3)}, the frequency deviation of the uplink signal of the UE is estimated to be about −½Δf_RA; if two valid peak values exist and are close, where one is located in the detection window {circle around (3)} and the other is located in the detection window {circle around (5)}, the frequency deviation of the uplink signal of the UE is estimated to be about 3/2Δf_RA; and so on.

Case 3: If one valid peak value exists and is located in the detection window {circle around (1)}, the frequency deviation of the uplink signal of the UE is estimated to be 0; if one valid peak value exists and is located in the detection window {circle around (2)}, the frequency deviation of the uplink signal of the UE is estimated to be −Δf_RA; if one valid peak value exists and is located in the detection window {circle around (4)}, the frequency deviation of the uplink signal of the UE is estimated to be −2Δf_RA; and so on.

It should be noted that step 205 is optional. To be specific, the frequency deviation is not estimated. Instead, a Message 3 is demodulated by grades according to a frequency deviation range. For example, when the frequency deviation range is [−3 KHz, 3 KHz], demodulation may be performed by six grades, where 1 KHz is a grade.

In the method for processing very-high-speed random access provided by the foregoing embodiment, a ZC sequence group is selected according to a cell type and a first Ncs, it is ensured that du_HT values of ZC sequences in the ZC sequence group meet a condition

${\mathrm{du}}_{\mathrm{HT}}\in \left[\mathrm{Ncs},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{4}\right]\bigcup \hspace{1em}\left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{4},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{3}\right]\bigcup \left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{3},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{2}\right],$

N non-overlap detection windows are set for each ZC sequence in the ZC sequence group according to the du_HT value of each ZC sequence in the ZC sequence group, where N=5, the valid peak values in the non-overlap detection windows are detected, and a round trip delay is determined. In this way, not only a problem of access of a UE to a network in a very-high-speed scenario where the frequency deviation range is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right]$

is solved, but also correctness of an estimated value of the RTD is improved.

As shown in FIG. 4, a method for processing very-high-speed random access according to an embodiment of the present invention, where N detection windows are set for each ZC sequence in a ZC sequence group when a frequency deviation range of the very-high-speed random access is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right],$

where N=5, is specifically described as follows:

401. Select a ZC sequence group according to a cell type and a first Ncs.

The cell type is a restricted cell, and the first Ncs represents a coverage range of the restricted cell.

Selection of the ZC sequence group may be obtained according to a selecting principle for root sequences of the restricted cell in the prior art, and therefore is not described herein any further.

402. Set N detection windows for each ZC sequence in the ZC sequence group, where N=5.

For relevant descriptions of the setting N detection windows for each ZC sequence in the ZC sequence group, reference may be made to step 202.

403. Send the cell type, a second Ncs, and the ZC sequence group to a UE, so that the UE selects a random access sequence from the ZC sequence group.

For relevant descriptions of the second Ncs, refer to step 102.

404. Receive a random access signal sent by the UE, and obtain the random access sequence from the random access signal.

405. Perform correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detect a primary peak value in the five detection windows of each ZC sequence, and determine a search window for a secondary peak value according to the primary peak value.

Search one maximum peak value in each of the five detection windows of each ZC sequence, and determine whether absolute positions of two maximum peak values in the five maximum peak values overlap. If the absolute positions do not overlap, select a greater maximum peak value of the two maximum peak values as the primary peak value. If the absolute positions overlap, select windows in which the two maximum peak values are located as windows in which the primary peak value is located. For example, when the primary peak value appears in an overlap between two detection windows, the primary peak value is detected separately in the two detection windows, that is, the same peak value is detected twice. Therefore, whether the peak values are the same peak value may be determined by determining whether the absolution positions of the two maximum peak values overlap.

TABLE 6
Search window for secondary peak value
Window where the primary         Search window for
peak value is located            secondary peak value
{circle around (1)}              {circle around (2)}{circle around (3)}
{circle around (2)}              {circle around (1)}{circle around (4)}
{circle around (3)}              {circle around (1)}{circle around (5)}
{circle around (4)}              {circle around (2)}
{circle around (5)}              {circle around (3)}
{circle around (2)}{circle around (5)} {circle around (1)}{circle around (3)}
{circle around (3)}{circle around (4)} {circle around (1)}{circle around (2)}
{circle around (4)}{circle around (5)} {circle around (2)}{circle around (3)}

For example, assuming that the primary peak value appears in an overlap between a detection window {circle around (4)} and a detection window {circle around (5)}, it can be known by referring to Table 6 that search windows for the secondary peak value are a window {circle around (2)} and a window {circle around (3)}.

406. Detect a secondary peak value in the search window for the secondary peak value, and determine, according to a combination of the detection window in which the primary peak value is located and a detection window in which the secondary peak value is located, a frequency deviation estimation window combination and an RTD estimation window.

Detect a secondary peak value in the search window for the secondary peak value. To be specific, find one maximum peak value in the search window for each secondary peak value, compare the maximum peak values, and select a greatest one which is greater than a detection threshold as the secondary peak value.

Determine the frequency deviation estimation window combination and the RTD estimation window by querying Table 7 according to the window in which the secondary peak value is located and the window in which the primary peak value is located.

For example, assuming that the primary peak value appears in an overlap between the detection window {circle around (4)} and the detection window {circle around (5)}, it can be known by referring to Table 7 that the secondary peak value is searched in the window {circle around (2)} and the window {circle around (3)}. When the secondary peak value is found in the detection window {circle around (2)}, the combination of detection windows after two peak value searches is {circle around (2)}, {circle around (4)} and {circle around (5)}. It can be known by referring to Table 7 that the detection window {circle around (4)} is selected to estimate the RTD, and the detection windows {circle around (2)} and {circle around (4)} are selected to estimate the frequency deviation. When the secondary peak value is found in the detection window {circle around (3)}, a combination of detection windows after two peak value searches is {circle around (3)}, {circle around (4)} and {circle around (5)}. It can be known by referring to Table 7 that the detection window {circle around (5)} is selected to estimate the RTD, and the detection windows {circle around (3)} and {circle around (5)} are selected to estimate the frequency deviation.

TABLE 7
Frequency deviation estimation window
combination and RTD estimation window
Window combination	Frequency deviation
after two peak value	estimation window
searches	combination	RTD estimation window
{circle around (1)}	Invariant	Single window itself
{circle around (2)}
{circle around (3)}
{circle around (4)}
{circle around (5)}
{circle around (1)}{circle around (2)}		Window in which the
{circle around (1)}{circle around (3)}		primary peak value is
{circle around (2)}{circle around (4)}		located
{circle around (3)}{circle around (5)}
{circle around (2)}{circle around (5)}	fail	—
{circle around (3)}{circle around (4)}
{circle around (2)}{circle around (3)}{circle around (4)}
{circle around (2)}{circle around (3)}{circle around (5)}
{circle around (2)}{circle around (3)}{circle around (4)}{circle around (5)}
{circle around (4)}{circle around (5)}
{circle around (1)}{circle around (2)}{circle around (5)}	{circle around (1)}{circle around (2)}	{circle around (2)}
{circle around (1)}{circle around (3)}{circle around (4)}	{circle around (1)}{circle around (3)}	{circle around (3)}
{circle around (2)}{circle around (4)}{circle around (5)}	{circle around (2)}{circle around (4)}	{circle around (4)}
{circle around (3)}{circle around (4)}{circle around (5)}	{circle around (3)}{circle around (5)}	{circle around (5)}

It should be noted that, if the frequency deviation estimation window combination shows fail, no user is detected in the detection windows of the ZC sequence. Otherwise, the RTD is estimated according to a designated RTD estimation window.

407. Determine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

The estimated value of the RTD is a deviation of the valid peak value in the RTD estimation window relative to a start position of the RTD estimation window. If the start position of the RTD estimation window is obtained by shifting preset sampling points, the estimated value of the RTD is a deviation value of the valid peak value in the RTD estimation window relative to the start position of the RTD estimation window plus or minus the number of the preset sampling points. The details are as follows.

Assuming that the start position of the RTD estimation window shifts left by the preset sampling points, the estimated value of the RTD is the deviation value of the start position of the RTD estimation window minus the number of the preset sampling points. Assuming that the start position of the RTD estimation window shifts right by the preset sampling points, the estimated value of the RTD is the deviation value of the start position of the RTD estimation window plus the number of the preset sampling points.

408. Determine an estimated value of the frequency deviation according to the frequency deviation estimation window combination.

For how to determine the estimated value of the frequency deviation according to the frequency deviation estimation window combination, reference may be made to relevant descriptions in step 206.

The estimated value of the frequency deviation is used for rectifying a deviation of an uplink signal of the UE, thereby demodulating a Message 3.

It should be noted that step 408 is optional. To be specific, the frequency deviation may not be estimated. Instead, a Message 3 is demodulated by grades according to a frequency deviation range. For example, when the frequency deviation range is [−3 KHz, 3 KHz], demodulation may be performed by six grades, where 1 KHz is a grade.

In the method for processing very-high-speed random access provided by the foregoing embodiment, a principle of selecting the ZC sequence for the restricted cell in the prior art is used to select a ZC sequence group, the five detection windows is set for each ZC sequence in the ZC sequence group, the valid peak value in the five detection windows of each ZC sequence is detected, and an RTD estimation window is determined according to a combination of the detection window in which the primary peak value is located and the detection window in which the secondary peak value is located, so that the estimated value of the RTD is determined. In this way, a problem of detecting the RTD when the valid peak value appears in the overlap between detection windows is solved, and processing of the random access signal in a very-high-speed movement scenario when the frequency deviation range is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right]$

is implemented, thereby improving access performance of a network.

As shown in FIG. 5, a method for processing very-high-speed random access according to an embodiment of the present invention, where N (N≥W) detection windows are set for each ZC sequence in a ZC sequence group when a frequency deviation range of the very-high-speed random access is

$\left[-\frac{W*\Delta f_{\mathrm{RA}}}{2},\frac{W*\Delta f_{\mathrm{RA}}}{2}\right],$

where W≥5, is specifically described as follows:

501. Select a ZC sequence group according to a cell type and a first Ncs.

Selection of the ZC sequence group is obtained according to a configuration principle for root sequences of a restricted cell, which belongs to the prior art, and therefore is not described herein any further.

For relevant descriptions of the cell type and the first Ncs, refer to step 101.

502. Set N detection windows for each ZC sequence in the ZC sequence group.

When the ZC sequence group includes M ZC sequences, the setting N detection windows for each ZC sequence in the ZC sequence group is specifically described as follows:

D1. Obtain a du_HT value of an i^th ZC sequence in the ZC sequence group.

For relevant descriptions of the du_HT value and an obtaining method, reference may be made to step 101, where a value of i is any integer in [1, M].

D2. Determine start positions of the N detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence.

The N detection windows {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)}, {circle around (5)}, {circle around (6)}, {circle around (7)} . . . of the i^th ZC sequence respectively correspond to frequency deviations _0/−Δf_RA/+Δf_RA/−2Δf_RA/+2Δf_RA/−3f_RA/+3Δf_RA/, . . . . The start positions are as follows:

a start position of the detection window {circle around (1)} is 0;

a start position of the detection window {circle around (2)} is mod(du_HT, Nzc);

a start position of the detection window {circle around (3)} is mod(−du_HT, Nzc);

a start position of the detection window {circle around (4)} is mod(2*du_HT, Nzc);

a start position of the detection window {circle around (5)} is mod(−2*du_HT, Nzc);

a start position of the detection window {circle around (6)} is mod(3*du_HT, Nzc);

a start position of the detection window {circle around (7)} is mod(−3*du_HT, Nzc); and

others can be so deduced;

where mod(du_HT, Nzc) means du_HT mod Nzc, and Nzc is a length of the i^th ZC sequence.

D3. Set the N detection windows of the i^th ZC sequence according to the start positions of the N detection windows of the i^th ZC sequence and a preset size of a detection window.

The size of the detection window may be configured according to a cell radius, and is no less than an RTD corresponding to the cell radius.

503. Send the cell type, a second Ncs, and the ZC sequence group to a UE, so that the UE selects a random access sequence from the ZC sequence group.

For relevant descriptions of the second Ncs, refer to step 102.

504. Receive a random access signal sent by the UE, and obtain the random access sequence from the random access signal.

505. Perform correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detect a valid peak value in the N detection windows of each ZC sequence, and determine an estimated value of the RTD according to the valid peak value.

For relevant descriptions of the valid peak value, reference may be made to step 104.

The determining an estimated value of the RTD according to the valid peak value may include step E1 and step E2, which are specifically described as follows:

E1. Determine an RTD estimation window according to a detection window in which the valid peak value is located.

If the detection window of the ZC sequence in which the valid peak value is located does not overlap with other detection windows of the ZC sequence, randomly select one from the detection windows in which the valid peak value is located as the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence but at least one valid peak value appears in a non-overlap, determine a detection window in which the at least one valid peak value is located as the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence, and the valid peak value appears in the overlap, perform frequency deviation processing on the random access signal according to frequency deviations of two detection windows in which a primary peak value of the valid peak values is located to obtain a new valid peak value, and determine the frequency deviation and the RTD estimation window according to the new valid peak value.

Other detection windows of the ZC sequence refer to detection windows in the N detection windows of the ZC sequence except the detection window in which the valid peak value is located.

For example, assuming that N detection windows are set for each ZC sequence in step 503 and step 504, where N=6. To be specific, each ZC sequence has detection windows {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)}, {circle around (5)}, and {circle around (6)}. If valid peak values are respectively detected in detection windows {circle around (3)} and {circle around (5)} of a first ZC sequence, determine whether detection windows {circle around (3)} and {circle around (5)} of the first ZC sequence overlap with other detection windows of the first ZC sequence, that is, detection windows {circle around (1)}, {circle around (2)}, {circle around (5)} and {circle around (6)} of the first ZC sequence.

That the detection windows overlap but at least one valid peak value appears in the non-overlap refers to that although the detection windows overlap, at least one valid peak value in the detected valid peak values appears in the non-overlap of the detection windows. At this moment, the detection window in which the valid peak value appearing in the non-overlap of the detection windows is located is selected to estimate the RTD. As shown in FIG. 6, it is described as follows by using five detection windows as an example.

As shown in FIG. 6(a), when a secondary peak value appears in a detection window {circle around (1)}, the detection window {circle around (1)} may be used to estimate an RTD.

As shown in FIG. 6(b), a primary peak value appears in an overlap between a detection window {circle around (2)} and a detection window {circle around (5)}, and no secondary peak value exists. New valid peak values are obtained after a frequency deviation of +1/−2f_RA is separately performed on a received signal, and frequency deviations are determined according to the new valid peak values, so as to determine an RTD estimation window.

As shown in FIG. 6(c), a primary peak value appears in an overlap between a detection window {circle around (3)} and a detection window {circle around (4)}, and a secondary peak value appears in an overlap between the detection window {circle around (2)} and the detection window {circle around (5)}. New valid peak values are obtained after a frequency deviation of −1.5/+1.5 Δf_RA is separately performed on the received signal, and frequency deviations are determined according to the new valid peak values, so as to determine the RTD estimation window.

As an embodiment, if the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence and the valid peak value appears in the overlap, it is determined that no random access signal is detected in the detection window in which the valid peak value is located. Random access initiated by a UE fails, and access is initiated again.

E2. Determine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

For a specific implementation method of step C2, reference may be made to relevant descriptions in step 407.

It should be noted that the method for processing very-high-speed random access provided by the embodiment is applicable to a case in which a frequency deviation range is

$\left[-\frac{W*\Delta f_{\mathrm{RA}}}{2},\frac{W*\Delta f_{\mathrm{RA}}}{2}\right]$

and W≥5. When W>5, N detection windows are set for the ZC sequences in the selected ZC sequence group, where N is no less than W.

In the foregoing embodiment, a principle of selecting the ZC sequence for a restricted cell in the prior art is used to select the ZC sequence group, the N detection windows are set for each ZC sequence in the ZC sequence group, the valid peak value in the N detection windows of each ZC sequence is detected, and an RTD estimation window according to a detection window in which the valid peak value is located is determined, so that the round trip delay is determined. In this way, a problem that it is difficult to detect the RTD correctly in a very-high-speed scenario when a frequency deviation range is

$\left[-\frac{W*\Delta f_{\mathrm{RA}}}{2},\frac{W*\Delta f_{\mathrm{RA}}}{2}\right]$

and W≥5 is solved, thereby improving access performance of a network.

As shown in FIG. 7, an apparatus for processing very-high-speed random access according to an embodiment of the present invention may be a base station, which includes a selecting unit 701, a setting unit 702, a sending unit 703, a receiving unit 704, and a detecting unit 705.

The selecting unit 701 is configured to select a ZC sequence group according to a cell type and a first Ncs.

The setting unit 702 is configured to set N detection windows for each ZC sequence in the ZC sequence group, where N≥5.

The sending unit 703 is configured to send the cell type, a second Ncs, and the ZC sequence group selected by the selecting unit 701 to a user equipment UE, so that the UE selects a random access sequence from the ZC sequence group.

The receiving unit 704 is configured to receive a random access signal sent by the UE, and obtain the random access sequence from the random access signal.

The detecting unit 705 is configured to perform correlation processing on the random access sequence obtained by the receiving unit 704 with each ZC sequence in the ZC sequence group, detect a valid peak value in the N detection windows set by the setting unit 702 for each ZC sequence, and determine an estimated value of a round trip delay RTD according to the valid peak value.

Optionally, corresponding to the method embodiment shown in FIG. 1, when the ZC sequence group selected by the selecting unit 701 includes M ZC sequences, the setting unit 702 is further configured to:

obtain a du_HT value of an i^th ZC sequence in the ZC sequence group;

determine start positions of the N detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence; and

set the N detection windows of the i^th ZC sequence according to the start positions of the N detection windows of the i^th ZC sequence and a preset size of a detection window.

The du_HT value of the i^th ZC sequence refers to a shift of a mirror image peak in a power delay profile PDP of the i^th ZC sequence relative to the RTD when a frequency deviation is

$\pm \frac{1}{T_{\mathrm{SEQ}}},$

where T_SEQ is a time duration occupied by the i^th ZC sequence and a value of i is any integer in [1, M]. For an obtaining method of the du_HT value, refer to relevant descriptions in step 101.

The size of a detection window may be configured according to a cell radius, and cannot be less than a maximum value of the RTD.

Optionally, when a frequency deviation range of the very-high-speed access is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right]$

and the ZC sequence selected by the selecting unit 701 includes M ZC sequences, that is, corresponding to the method embodiment shown in FIG. 2, the setting unit 702 is further configured to:

obtain a du_HT value of the i^th ZC sequence in the ZC sequence group; and

set five detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence.

The du_HT value of the i^th ZC sequence refers to a shift of a mirror image peak in a power delay profile PDP of the i^th ZC sequence relative to the RTD when a frequency deviation is

$\pm \frac{1}{T_{\mathrm{SEQ}}},$

where T_SEQ is a time duration occupied by the i^th ZC sequence and a value of i is any integer in [1, M]. For an obtaining method of the du_HT value, refer to relevant descriptions in step 101.

Optionally, when the frequency deviation range of the very-high-speed random access is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right]$

and N detection windows are set for each ZC sequence in the ZC sequence group, where N=5, that is, corresponding to the method embodiment shown in FIG. 2, the setting unit 702 is further configured to:

obtain start positions of the five detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence, where

a start position of a detection window {circle around (1)} is 0;

a start position of a detection window {circle around (2)} is mod(du_HT, Nzc);

a start position of a detection window {circle around (3)} is mod(−du_HT, Nzc);

a start position of a detection window {circle around (4)} is mod(2*du_HT, Nzc);

a start position of a detection window {circle around (5)} is mod(−2*du_HT, Nzc); and

set the five detection windows of the i^th ZC sequence according to the start positions of the five detection windows and a preset size of a detection window.

Nzc is a length of the i^th ZC sequence. For an obtaining method of the du_HT value, refer to relevant descriptions in step 101. For relevant descriptions of the preset size of the detection window, refer to step 104. The five detection windows {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)} and {circle around (5)} respectively correspond to frequency deviations 0, −Δf_RA, +Δf_RA, −2Δf_RA and +2Δf_RA.

Optionally, when the frequency deviation range of the very-high-speed random access is

$\left[-\frac{5*\Delta f_{\mathrm{RA}}}{2},\frac{5*\Delta f_{\mathrm{RA}}}{2}\right],$

corresponding to the method embodiment shown in FIG. 2, the setting unit 701 is further configured to:

determine whether du_HT values of ZC sequences in the selected ZC sequence group meet a condition

${\mathrm{du}}_{\mathrm{HT}}\in \left[\mathrm{Ncs},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{4}\right]\bigcup \hspace{1em}\left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{4},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{3}\right]\bigcup \left[\frac{\mathrm{Nzc}+\mathrm{Ncs}}{3},\frac{\mathrm{Nzc}-\mathrm{Ncs}}{2}\right],$

where, in the condition, the Ncs is the first Ncs, and the Nzc is a length of a ZC sequence;

if the du_HT value of at least one ZC sequence in the selected ZC sequence group does not meet the condition, reselect a ZC sequence group according to the cell type and the first Ncs; and

if the du_HT values of the ZC sequences in the selected ZC sequence group all meet the condition, send the selected ZC sequence group to the setting unit 702 and the sending unit 703.

Optionally, corresponding to the method embodiment shown in FIG. 4, the detecting unit 704 is further configured to:

detect a primary peak value in the valid peak values in the five detection windows of each ZC sequence in the ZC sequence group;

determine a search window for a secondary peak value in the valid peak values according to a detection window in which the primary peak value is located;

detect the secondary peak value in the search window for the secondary peak value, and determine an RTD estimation window according to a combination relation between the detection window in which the primary peak value is located and a detection window in which the secondary peak value is located; and

determine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

Optionally, corresponding to the method embodiment shown in FIG. 5, the setting unit 702 is further configured to:

determine start positions of the N detection windows of the i^th ZC sequence according to the du_HT value of the i^th ZC sequence in the ZC sequence group as follows:

a start position of a detection window {circle around (1)} is 0;

a start position of a detection window {circle around (2)} is mod(du_HT, Nzc);

a start position of a detection window {circle around (3)} is mod(−du_HT, Nzc);

a start position of a detection window {circle around (4)} is mod(2*du_HT, Nzc);

a start position of a detection window {circle around (5)} is mod(−2*du_HT Nzc);

a start position of the detection window {circle around (6)} is mod(3*du_HT, Nzc).

a start position of a detection window {circle around (7)} is mod(−3*du_HT, Nzc); and

others can be so deduced;

where mod(du_HT, Nzc) means du_HT mod Nzc, and Nzc is a length of the i^th ZC sequence; and

set the N detection windows of the i^th ZC sequence according to the start positions of the N detection windows of the i^th ZC sequence and a preset size of a detection window.

The N detection windows {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)}, {circle around (5)} . . . of the ZC sequence respectively correspond to frequency deviations 0, −Δf_RA, +Δf_RA, −2Δf_RA, +2Δf_RA, −3Δf_RA and +3Δf_RA, . . . .

The detecting unit 704 is further configured to:

determine an RTD estimation window according to a detection window in which the valid peak value is located; and

if the detection window of the ZC sequence in which the valid peak value is located does not overlap with other detection windows of the ZC sequence, randomly select one from the detection windows in which the valid peak value is located as the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence, but at least one valid peak value appears in a non-overlap, determine a detection window in which the at least one valid peak value is located as the RTD estimation window; or

if the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence, and the valid peak value appears in an overlap, determine that no random access signal is detected in the detection window in which the valid peak value is located; or perform frequency deviation processing on the random access signal according to frequency deviations of two detection windows in which a primary peak value of the valid peak values is located to obtain a new valid peak value, and determine the frequency deviation and the RTD estimation window according to the new valid peak value; and

determine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

Relevant descriptions of other detection windows in the ZC sequence are consistent with those in step 507.

Optionally, the detecting unit 704 is further configured to:

estimate the frequency deviation according to a detection window in which the valid peak value is located.

For the estimating the frequency deviation according to a detection window in which the valid peak value is located, refer to step 206.

It should be noted that the selecting unit 701, the setting unit 702, the sending unit 703, the receiving unit 704, and the detecting unit 705 may all be a CPU, a digital signal processor, or other processors.

The apparatus for processing very-high-speed random access provided by the foregoing embodiment solves a problem that an RTD of a random access signal cannot be correctly detected in a very-high-speed scenario, ensures that a user equipment moving at a very high speed can correctly adjust a TA value according to a detected RTD, and therefore correctly adjusts message sending timing, so that the user equipment in a very-high-speed scenario can normally access a network, thereby improving access performance of the network.

A system for processing very-high-speed random access provided by the embodiment includes the apparatus for processing very-high-speed random access shown in FIG. 7.

Persons of ordinary skill in the art may understand that all or a part of the steps of the foregoing method embodiments may be implemented by a program instructing relevant hardware. The program may be stored in a computer readable storage medium. When the program runs, the steps of the foregoing method embodiments are performed. The storage medium may include any medium capable of storing program code, such as a ROM, a RAM, a magnetic disk, or an optical disc.

Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present invention rather than limiting the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, persons of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments, or make equivalent replacements to some technical features thereof, as long as such modifications or replacements do not cause the essence of corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for processing very-high-speed random access, comprising: selecting, by a base station, a Zadoff-Chu (ZC) sequence group according to a cell type and a first cyclic shift parameter Ncs, wherein the ZC sequence group comprises M ZC sequences, and a duHT value of a jth ZC sequence in the ZC sequence group meets a condition

2. The method according to claim 1, wherein the method further comprises: setting N detection windows for each ZC sequence in the ZC sequence group, wherein N≥5.

3. The method according to claim 2, wherein the method further comprises: receiving a random access signal from the UE, and obtaining the random access sequence from the random access signal; andperforming correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detecting a valid peak value in the N detection windows of each ZC sequence, and determining an estimated value of a round trip delay (RTD) according to the valid peak value.

4. The method according to claim 3, wherein the setting N detection windows for each ZC sequence in the ZC sequence group comprises: obtaining a duHT value of an ith ZC sequence in the ZC sequence group;determining start positions of N detection windows of the ith ZC sequence according to the duHT value of the ith ZC sequence; andsetting the N detection windows of the ith ZC sequence according to the start positions of the N detection windows of the ith ZC sequence and a preset size of a detection window;wherein the duHT value of the ith ZC sequence corresponds to a shift of a mirror image peak in a power delay profile (PDP) of the ith ZC sequence relative to the RTD when a frequency deviation is

5. The method according to claim 3, wherein, when a frequency deviation range of very-high-speed random access is

6. The method according to claim 5, wherein the setting five detection windows of the ith ZC sequence according to the duHT value of the ith ZC sequence comprises: obtaining start positions of the five detection windows of the ith ZC sequence according to the duHT value of the ith ZC sequence, wherein the five detection windows are a detection window {circle around (1)}, a detection window {circle around (2)}, a detection window {circle around (3)}, a detection window {circle around (4)} and a detection window {circle around (5)}, respectively;a start position of the detection window {circle around (1)} is 0;a start position of the detection window {circle around (2)} is mod(duHT, Nzc);a start position of the detection window {circle around (3)} is mod(−duHT, Nzc);a start position of the detection window {circle around (4)} is mod(2*duHT, Nzc); anda start position of the detection window {circle around (5)} is mod(−2*duHT, Nzc);wherein Nzc is a length of the ith ZC sequence; andsetting the five detection windows of the ith ZC sequence according to the start positions of the five detection windows and a preset size of a detection window.

7. The method according to claim 3, wherein the detecting a valid peak value in the N detection windows of each ZC sequence, and determining an estimated value of a round trip delay (RTD) according to the valid peak value comprises: detecting a primary peak value in the valid peak values in the N detection windows of each ZC sequence;determining a search window for a secondary peak value in the valid peak values according to a detection window in which the primary peak value is located;detecting the secondary peak value in the search window for the secondary peak value, and determining an RTD estimation window according to a combination relation between the detection window in which the primary peak value is located and a detection window in which the secondary peak value is located; anddetermining the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

8. The method according to claim 3, wherein the determining an estimated value of an RTD according to the valid peak value comprises: determining an RTD estimation window according to a detection window in which the valid peak value is located; anddetermining the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

9. The method according to claim 3, wherein the method further comprises: estimating the frequency deviation according to a detection window in which the valid peak value is located.

10. The method according to claim 1, wherein the method further comprises: when the duHT value of at least one ZC sequence in the ZC sequence group does not meet the condition, reselecting a ZC sequence group according to the cell type and the first Ncs.

11. An apparatus for processing very-high-speed random access, comprising: a processor; anda computer readable storage medium to store instructions which, when executed by the processor, configure the processor to:select a Zadoff-Chu(ZC) sequence group according to a cell type and a first cyclic shift parameter Ncs, wherein the ZC sequence group comprises M ZC sequences, and a duHT value of a jth ZC sequence in the ZC sequence group meets a condition

12. The apparatus according to claim 11, wherein the processor is further configured to: set N detection windows for each ZC sequence in the ZC sequence group, wherein N≥5.

13. The apparatus according to claim 12, wherein the processor is further configured to: receive a random access signal sent by the UE and obtain the random access sequence from the random access signal; andperform correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detect a valid peak value in the N detection windows for each ZC sequence, and determine an estimated value of a round trip delay (RTD) according to the valid peak value.

14. The apparatus according to claim 13, wherein the processor is further configured to: obtain a duHT value of an ith ZC sequence in the ZC sequence group;determine start positions of N detection windows of the ith ZC sequence according to the duHT value of the ith ZC sequence; andset the N detection windows of the ith ZC sequence according to the start positions of the N detection windows of the ith ZC sequence and a preset size of a detection window;wherein the duHT value of the ith ZC sequence corresponds to a shift of a mirror image peak in a power delay profile (PDP) of the ith ZC sequence relative to the RTD when a frequency deviation is

15. The apparatus according to claim 13, wherein, when a frequency deviation range of very-high-speed random access is

16. The apparatus according to claim 15, wherein the processor is further configured to: obtain start positions of the five detection windows of the ith ZC sequence according to the duHT value of the ith ZC sequence,wherein the five detection windows are a detection window {circle around (1)}, a detection window {circle around (2)}, a detection window {circle around (3)}, a detection window {circle around (4)} and a detection window {circle around (5)}, respectively;a start position of the detection window {circle around (1)} is 0;a start position of the detection window {circle around (2)} is mod(duHT, Nzc);a start position of the detection window {circle around (3)} is mod(−duHT, Nzc);a start position of the detection window {circle around (4)} is mod(2*duHT, Nzc); anda start position of the detection window {circle around (5)} is mod(−2*duHT, Nzc);wherein Nzc is a length of the ith ZC sequence; andset the five detection windows of the ith ZC sequence according to the start positions of the five detection windows and a preset size of a detection window.

17. The apparatus according to claim 11, wherein the processor is further configured to: when the duHT value of at least one ZC sequence in the ZC sequence group does not meet the condition, reselect a ZC sequence group according to the cell type and the first Ncs.

18. The apparatus according to claim 13, wherein the processor is further configured to: detect a primary peak value in the valid peak values in the N detection windows of each ZC sequence in the ZC sequence group;determine a search window for a secondary peak value in the valid peak values according to a detection window in which the primary peak value is located;detect the secondary peak value in the search window for the secondary peak value, and determine an RTD estimation window according to a combination relation between the detection window in which the primary peak value is located and a detection window in which the secondary peak value is located; anddetermine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

19. The apparatus according to claim 13, wherein the processor is further configured to: determine an RTD estimation window according to a detection window in which the valid peak value is located; andwhen the detection window of the ZC sequence in which the valid peak value is located does not overlap with other detection windows of the ZC sequence, randomly select one from detection windows in which the valid peak value is located as the RTD estimation window; orwhen the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence, but at least one valid peak value appears in a non-overlap, determine a detection window in which the at least one valid peak value is located as the RTD estimation window; orwhen the detection window of the ZC sequence in which the valid peak value is located overlaps with other detection windows of the ZC sequence, and the valid peak value appears in an overlap, determine that no random access signal is detected in the detection window in which the valid peak value is located; or perform frequency deviation processing on the random access signal according to frequency deviations of two detection windows in which a primary peak value of the valid peak value is located to obtain a new valid peak value, and determine the frequency deviation and the RTD estimation window according to the new valid peak value; anddetermine the estimated value of the RTD according to a position of the valid peak value in the RTD estimation window.

20. The apparatus according to claim 13, wherein the processor is further configured to: estimate the frequency deviation according to a detection window in which the valid peak value is located.