System and method for optimizing Walsh code assignments

Abstract

A wireless communication system is disclosed, including a network and a plurality of base stations coupled to the network, wherein each of the base stations are adapted to transmit only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes. In the wireless communication system, the base station may be further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wi+j+ln to Wn−1n. Alternatively, the base station may be further adapted to transmit traffic channel information using a second group of adjacent Walsh codes W0n to Wi−1n. Alternatively, the base station may be further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wint(j/2+)n/2 to Wn/2−ln/2 or W0n/2 to Wint(i/2−l)n/2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an exemplary wireless communication system in accordance with an aspect of the invention;

FIG. 2 illustrates a block diagram of an exemplary base station in accordance with an aspect of the invention;

FIG. 3 illustrates a diagram of a Walsh code tree in accordance with the IS-95 protocol;

FIG. 4 illustrates a diagram of an exemplary Walsh code tree in accordance with an aspect of the invention;

FIG. 5A illustrates a block diagram of an exemplary base station in accordance with another aspect of the invention;

FIG. 5B illustrates a flow diagram of an exemplary method implemented by a base station in accordance with another aspect of the invention;

FIG. 6A illustrates a block diagram of an exemplary subscriber unit in accordance with another aspect of the invention; and

FIG. 6B illustrates a flow diagram of an exemplary method implemented by a subscriber unit station in accordance with another aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 illustrates a diagram of an exemplary Walsh code tree 400 in accordance with an aspect of the invention. The new Walsh code tree 400 can be used in wireless communication system 100 and by base stations 104, 106, and 200, as discussed above. In addition, the new Walsh code tree 400 can be used in a base station and subscriber unit as are described with reference to FIG. 5A and 6A discussed below.

According to the new Walsh code tree 400, the Pilot channel is assigned to the first Walsh code W₀⁶⁴, the Paging channels are assigned to the second and third Walsh codes W₁⁶⁴-W₂⁶⁴, the Sync channel is assigned to the fourth Walsh Code W₃⁶⁴, and the traffic channels are assigned to the remaining Walsh codes W₄⁶⁴-W₆₃⁶⁴. With this new Walsh code tree 400, only two 32-length Walsh codes are used for the Pilot, Paging, and Sync Channels. Accordingly, there are 30 32-length Walsh codes available for traffic channel. In addition, according to the new Walsh code tree 400, the Pilot, Paging, and Sync channels use adjacent Walsh codes W₀⁶⁴-W₃⁶⁴ situated at the top end of the Walsh code tree. This arrangement allows the traffic channels to be assigned to a continuous block of adjacent Walsh codes W₄⁶⁴-W₆⁶⁴ for IS-95, and W₂³²-W₃₁³² for 1xEV-DV. Although only two Paging channels are used to exemplify the invention, it shall be understood that the new Walsh code assignment 400 may include one or more Paging channels.

The new Walsh code tree 400 utilizes channel resources more efficiently than that of Walsh code tree 300. For instance, the new Walsh code assignment 400 has 30 codes reserved for traffic channels, whereas the old Walsh code assignment 300 only has 27 codes reserved for traffic channels. Furthermore, the process of selecting a traffic channel using the new Walsh code assignment 400 is much simpler because it has a continuous block of Walsh codes for traffic channels, whereas it is much more difficult for the old Walsh code assignment since it has discontinuous blocks of Walsh codes for traffic channels.

In general, according to the new Walsh code assignment 400, the Pilot, Paging, and Sync channels (i.e. non-traffic channels) are assigned to adjacent Walsh codes W_iⁿ-W_i+jⁿ (where i and j are integers, and n is the length of the Walsh codes). In addition, the Pilot, Paging, and Sync channels (i.e. non-traffic channels) may be assigned to either ends of the Walsh codes W_iⁿ-W_i+jⁿ (where i=0 or i+j=n−1). If the Pilot, Paging, and Sync channels are assigned to either end of the Walsh codes, the traffic channels may be assigned to the remaining Walsh codes W_i+j+1ⁿ to W_n−1ⁿ or W₀ⁿ to W_i−1ⁿ. Alternatively, the traffic channels may be assigned to W_int(j/2+1)^n/2 to W_n/2−1^n/2 or W₀^n/2 to W_int(i/2−1)^n/2.

FIG. 5A illustrates a block diagram of an exemplary base station 500 in accordance with another aspect of the invention. The base station 500 is an exemplary detailed version of base stations 104 and 106 of the wireless communication system 100. The base station 500 comprises a processor 502, a radio frequency (RF) interface 504, an antenna 506, a network interface 508, and a memory 510.

The processor 502 performs the various operations of the base station 500 as described with reference to FIG. 5B. The RF interface 504 and antenna 506 provide the base station 500 with an interface to the wireless medium for transmitting communications to and receiving communications from SUs. The network interface 508 provides the base station 500 with an interface to the network 102 for transmitting communications to and receiving communications from various network devices. The memory 510, serving generally as a computer readable medium, stores one or more software module(s) that control the operations of the processor 502, the set of Walsh codes assigned to the various channels according to the new assignment described herein, and information transmitted via the Pilot, Paging, and Sync channels.

FIG. 5B illustrates a flow diagram of an exemplary method 550 implemented by the base station 500 in accordance with another embodiment of the invention. According to the method 550, the processor 502 transmits the Pilot information via the RF interface 504 and antenna 506 per the new Walsh code assignments (e.g., W₀⁶⁴) (block 552). The processor 502 also transmits the Paging information via the RF interface 504 and antenna 506 per the new Walsh code assignments (e.g., W₁⁶⁴-W₂⁶⁴) (block 554). The processor 502 also transmits the Sync information via the RF interface 504 and antenna 506 per the new Walsh code assignments (e.g., W₃⁶⁴) (block 556). And, the processor 502 transmits the traffic channel information received by way of the network interface 508 to the SUs via the RF interface 504 and antenna 506 per the new Walsh code assignments (e.g., W₄⁶⁴-W₆₃⁶⁴ or W₂³²-W₃₁³²) (block 558).

FIG. 6A illustrates a block diagram of an exemplary subscriber unit 600 in accordance with another aspect of the invention. The subscriber unit 600 is an exemplary detailed version of subscriber units 108, 110, 112 of the wireless communication system 100. The subscriber unit 600 comprises a processor 602, an RF interface 604, an antenna 606, and a memory 608.

The processor 602 performs the various operations of the subscriber unit 600 as described with reference to FIG. 6B. The RF interface 604 and antenna 606 provide the subscriber unit 600 with an interface to the wireless medium for transmitting communications to and receiving communications from base stations. The memory 608, serving generally as a computer readable medium, stores one or more software module(s) that control the operations of the processor 602, and a set of Walsh codes assigned to the various channels according to the new assignment described herein.

FIG. 6B illustrates a flow diagram of an exemplary method 650 implemented by the subscriber unit 600 in accordance with another embodiment of the invention. According to the method 650, the processor 602 receives the Pilot information via the RF interface 604 and antenna 606 per the new Walsh code assignments (e.g., W₀⁶⁴) (block 652). The processor 602 also receives the Paging information via the RF interface 604 and antenna 606 per the new Walsh code assignments (e.g., W₁⁶⁴-W₂⁶⁴) (block 654). The processor 602 also receives the Sync information via the RF interface 604 and antenna 606 per the new Walsh code assignments (e.g., W₃⁶⁴) (block 656). And, the processor 602 receives the traffic channel information received via the RF interface 604 and antenna 606 per the new Walsh code assignments (e.g., W₄⁶⁴-W₆₃⁶⁴ or W₂³²-W₃₁³²) (block 658).

Although the exemplary embodiments have been described with reference to a fixed length Walsh code system, it shall be understood that may be applicable to systems using variable-length Walsh codes, e.g. a system in compliance with CDMA 2000.

While the invention has been described in connection with various embodiments, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.

Claims

1. A wireless communication system, comprising: a network; anda plurality of base stations coupled to said network, wherein each of said base stations are adapted to transmit only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of each of the Walsh codes.

2. The wireless communication system of claim 1, wherein said base station is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

3. The wireless communication system of claim 1, wherein said base station is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes W0n to Wi−1n.

4. The wireless communication system of claim 1, wherein said base station is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

5. The wireless communication system of claim 1, wherein said base station is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

6. The wireless communication system of claim 1, wherein i is equal to zero.

7. The wireless communication system of claim 6, wherein the Pilot channel information is transmitted using Walsh code W0n.

8. The wireless communication system of claim 1, wherein the Sync channel information is transmitted using Walsh code Wi+jn.

9. The wireless communication system of claim 1, wherein the one or more Paging channels are transmitted using one or more Walsh codes Wi+1n to Wi+j−1n.

10. A base station, comprising: an RF interface;an antenna; anda processor to transmit only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

11. The base station of claim 10, wherein said processor is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

12. The base station of claim 10, wherein said processor is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes W0n to Wi−1n.

13. The base station of claim 10, wherein said processor is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

14. The base station of claim 10, wherein said processor is further adapted to transmit traffic channel information using a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

15. A method comprising transmitting only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

16. The method of claim 15, further comprising transmitting traffic channel information using a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

17. The method of claim 15, wherein transmitting traffic channel information comprises using a second group of adjacent Walsh codes W0n to Wi−1n.

18. The method of claim 15, wherein transmitting traffic channel information comprises using a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

19. The method of claim 15, wherein transmitting traffic channel information comprises using a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

20. A computer readable medium including one or more software modules to control a processor to transmit only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

21. The computer readable medium of claim 20, wherein said one or more software modules are adapted to control a processor to transmit traffic channel information using a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

22. The computer readable medium of claim 20, wherein said one or more software modules are adapted to control a processor to transmit traffic channel information using a second group of adjacent Walsh codes W0n to Wi−1n.

23. The computer readable medium of claim 20, wherein said one or more software modules are adapted to control a processor to transmit traffic channel information using a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

24. The computer readable medium of claim 20, wherein said one or more software modules are adapted to control a processor to transmit traffic channel information using a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

25. A base station, comprising: an antenna;an up converter including an output coupled to said antenna;an I- and Q-modulator including an output coupled to said up converter;a summer including an output coupled to said I- and Q-modulator;a plurality of modulo-2 adders including respective inputs to receive Pilot channel information, one or more Paging channel information, and a Sync channel information, and other inputs to receive Walsh codes in a manner that said Pilot channel information, one or more Paging channel information, and a Sync channel information are modulo-2 added respectively with adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

26. The base station of claim 25, further including other modulo-2 adders adapted to modulo-2 add traffic channel information with adjacent Walsh codes Wi+j+1n to Wn−1n.

27. The base station of claim 25, further including modulo-2 adders adapted to modulo-2 add traffic channel information with adjacent Walsh codes W0n to Wi−1n.

28. The base station of claim 25, further including modulo-2 adders adapted to modulo-2 add traffic channel information with adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

29. The base station of claim 25, further including modulo-2 adders adapted to modulo-2 add traffic channel information with adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

30. A subscriber unit, comprising: an RF interface;an antenna; anda processor to receive only a Pilot channel information, one or more Paging channel information, and a Sync channel information by way of said antenna and said RF interface using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

31. The subscriber unit of claim 30, wherein said processor is further adapted to receive traffic channel information by way of said antenna and said RF interface using any in a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

32. The subscriber unit of claim 30, wherein said processor is further adapted to receive traffic channel information by way of said antenna and said RF interface using any in a second group of adjacent Walsh codes W0n to Wi−1n.

33. The subscriber unit of claim 30, wherein said processor station is further adapted to receive traffic channel information by way of said antenna and said RF interface using any in a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

34. The subscriber unit of claim 30, wherein said processor station is further adapted to receive traffic channel information by way of said antenna and said RF interface using any in a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

35. A method comprising receiving only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

36. The method of claim 35, further comprising receiving traffic channel information using any in a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

37. The method of claim 35, wherein receiving traffic channel information comprises using any in a second group of adjacent Walsh codes W0n to Wi−1n.

38. The method of claim 35, wherein receiving channel information comprises using any in a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

39. The method of claim 35, wherein receiving channel information comprises using any in a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.

40. A computer readable medium including one or more software modules to control a processor to receive only a Pilot channel information, one or more Paging channel information, and a Sync channel information using a first group of adjacent Walsh codes Win to Wi+jn, where i and j are integers, and n is the length of the Walsh codes.

41. The computer readable medium of claim 40, wherein said one or more software modules are adapted to control a processor to receive traffic channel information using any in a second group of adjacent Walsh codes Wi+j+1n to Wn−1n.

42. The computer readable medium of claim 40, wherein said one or more software modules are adapted to control a processor to receive traffic channel information using any in a second group of adjacent Walsh codes W0n to Wi−1n.

43. The computer readable medium of claim 40, wherein said one or more software modules are adapted to control a processor to receive traffic channel information using any in a second group of adjacent Walsh codes Wint(j/2+1)n/2 to Wn/2−1n/2.

44. The computer readable medium of claim 40, wherein said one or more software modules are adapted to control a processor to receive traffic channel information using any in a second group of adjacent Walsh codes W0n/2 to Wint(i/2−1)n/2.