Patent Grant
8311494
This invention relates to a test unit, a data carrier, a transmitter component, a transmitter unit, a method for testing, a method for optimising component of a transmitter, and a computer program product.
In the art of data communication, it is known to test a transmitter unit for the power outputted in the different frequency bands. For instance, 3GPP standard document 3G TS 51.010-1 provides specification for testing whether or not an output RF spectrum (ORFS) of an Enhanced Data rates for Global Evolution (EDGE) transceiver complies with the requirements set by the part of the 3G standards relating to EDGE telecommunication systems.
Known methods for testing whether or not the output RF spectrum complies with the EDGE standard include observing the output power spectrum over a couple of hundreds of bursts. The burst include a random bit pattern. The bursts are generated by generating data packets incorporating the random bit pattern in the data packet and generating a phase shift keying (PSK) modulated signal according to the generated data packet. The PSK modulated signal is subsequently inputted to the transmitter unit to be tested. The RF spectrum of the signals outputted by the transmitter unit is monitored to measure whether the ORFS complies with the EDGE standards.
However, a general disadvantage of the known test methods is that they are time consuming since hundreds of burst are used to get an accurate and stable measurement. Furthermore, the known test methods do not give a clear insight in the characteristics of the tested components.
The present invention provides a test unit, a data carrier, a transmitter component, a transmitter unit, a method for testing, a method for optimising component of a transmitter, and a computer program product as described in the accompanying claims.
Specific embodiments of the invention are set forth in the dependent claims.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Further details, aspects and embodiments will be described, by way of example only, with reference to the drawings.
Referring to the example of
As shown in
A test signal Stest, for example a modulated signal SRF, may be generated in accordance with the test pattern T. For example, a base-band test signal Sbase corresponding to the test pattern T may be generated. For instance, the test pattern T may consist of binary numbers and a digital base-band test signal Sbase may be generated in accordance with the order and binary values in the test pattern T. The digital signal Sbase may then be modulated to generate a modulated test signal SRF. Also, for example, the modulated signal SRF may be generated by controlling one or more modulation parameters in accordance with the test pattern T. For instance, the test pattern T may include a sequence of (decimal) symbols and a parameter of the modulated signal SRF may be set to a value corresponding to the respective symbol. The modulation parameter may for example be the phase φ, the amplitude A, or the frequency f of the signal Stest. For example, the phase φ of a periodic signal may be varied in accordance with the symbol in the test pattern T, as is explained below in more detail, and the periodic signal may be mixed with another signal to obtain a modulated signal.
As shown in the example of
The transmitter 2 may generate a test signal Stest, such as a modulated test signal SRF, from the test pattern T. However, as is explained below in more detail with reference to
The test unit 1 may further be implemented as a part of a telecommunication system and for example be integrated in an integrated circuit package. As shown in
For instance, separate components 21,22 of a transmitting unit 2 may be tested. The test unit 1 itself may include one or more transmitter components 21,22. The transmitter components in the test unit 1 may be components which would be positioned in a transmitting unit, in a signal processing direction, upstream of the component to be tested and which can generate the signal to be inputted in the transmitter component to be tested. For example, as shown in
As shown in
As is explained below in more detail, the first predetermined data sequence T1 may cause the modulated signal SRF to have, during a first period of time, a first signal part S1 with a first frequency spectrum and the second predetermined data sequence T2 may cause, during a second period of time different from the first period of time, the modulated signal SRF to have a second signal part S2 with a second frequency spectrum. Thereby, the effect of the component 21,22 to be tested on the spectrum of the modulated signal can be determined in a relatively simple manner.
For instance, the part of the signal outputted by the component 21,22 which corresponds to the first signal part S1 may be compared with a first criterion and the part of the signal outputted by the component 21,22 which corresponds to the second signal part S2 may be compared with the second criterion, Also, for example, a comparison may be made between the part of the signal outputted by the component 21,22 which corresponds to the first signal part S1 with the first signal part S1. Furthermore, a comparison may be made between the part of the signal outputted by the component 21,22 which corresponds to the first signal part S1 part of the signal outputted by the component 21,22 which corresponds to the second signal part S2.
Furthermore, the time required to determine the effect of the component 21,22 to be tested on the spectrum of the modulated signal can be relatively short since, by means of the first and second predetermined data sequence T1,T2, the desired test conditions, may be made to occur. The first and second predetermined data sequence T1,T2 may for instance be selected in such a manner that a desired amount of difference in the relevant aspects of the frequency spectrum may be obtained. For example, as is explained below in more detail, the first predetermined data sequence T1 may cause a modulated signal spectrum with an upper side band (rejected side band) which is much stronger than the lower side band at a desired frequency of interest and the second predetermined data sequence T2 may cause in the same manner a modulated signal spectrum with a lower side band which is much stronger than the upper side band (rejected side band), thus enabling to test extreme cases of distortion of the RF frequency spectrum caused by modulated signal (modulation switching Output RF spectrum)
The test unit 1 may for instance be used to optimise the frequency behaviour of one or more components 21,22 of a transmitter 2 of modulated signals. For example, the test pattern T may be used to generate the modulated test signal SRF and cause the tested component(s) of the transmitter 2 to output a signal. As shown in
As for instance shown in
As shown in
The test pattern T may be inputted to the transmitter 2 in any suitable manner and the data source 11 may be any type of data source suitable for the specific implementation. For instance, the data source 11 may generate data packets with a payload in which the predetermined data sequences T1,T2 are included, or generates the sequences T1 and/or T2 in a continuous manner. The data packets may for example comply with a data communication standard, and may for instance be EDGE bursts. Referring to
As shown, the data packet 400 may include an initial tail 401, a first data part 402, a training sequence 403, a second data part 404, a final tail 405 and a guard period 406. Each segment 401-406 may for example have the number of symbols as listed in Table 1.
The initial tail 401 ramp-up of the test signal outputted by the transmitter 2. The training sequence 403 may be used to determine characteristics of the communication channel. The final tail 405 may include data used in error correction, The guard period 406 is used during the gradual reduction (ramp-down) of the test signal. The first and second data parts 402,404 may include user data, for example data outputted by a signal processor 112.
The first and second data parts 402,404 may for instance include the test pattern T. For example, the first predetermined data sequence T1 may be included in the first data part 402 and the second predetermined data sequence T2 may be included in the second data part 404. An example of a suitable sequence of symbols of a EDGE burst is listed in Table 2, in which the predetermined sequences T1,T2 are shown in bold typeface and underlined. It will, however, be apparent that other sequences may also be used.
As shown in table 2, the test pattern, formed in the example of Table 2 by the data in the first and second data parts 402,404, may include, in addition to the predetermined sequences T1,T2 additional data The test pattern T of data may for example include compensating data which compensate a parameter of the test signal Stest for an effect on the parameter caused by the first predetermined data sequence T1 and/or by the second predetermined data sequence T2. For instance, the compensation data may be selected such that the power level of the modulated signal SRF is compensated, relative to a power level of a reference modulated signal. The compensation data may for example be a pseudo random sequence (PN15 for example). conformed to a peak-to-average and a peak-to-minimum of an EDGE modulated signal.
The first predetermined data sequence T1 and the second predetermined data sequence T2 may differ in any suitable manner. For example, the first predetermined data sequence T1 and the second predetermined data sequence T2 may cause in the modulated signal SRF a first signal part S1 and a second signal part S2 respectively, which differ in the frequency components in any suitable manner. For example, the first signal part S1 may have one or more frequency components with a frequency f+ above a carrier frequency f0 which have a higher intensity than corresponding frequency component(s) f+ in the second signal part S2. The second signal part S2 may have one or more frequency components with a frequency f below the carrier frequency f0 with a higher intensity than a corresponding frequency component in the first signal part S1.
The first signal part S1 and the second signal part S2 may for example each have the frequency spectrum of a single-sideband modulated signal. The frequency component of the first signal part S1 may for example be the first upper side band of the modulated signal Srf above the carrier frequency f0 and/or the frequency component of the second signal part S2 may be the first lower side band of the modulated signal SRF, that is the first frequency band below the band of the carrier frequency f0.
The test unit 1 may be implemented in any manner suitable for the specific implementation. The test unit 1 may for instance include one or more units which perform different functions. As shown in
As shown in
The predetermined data sequences T1,T2 may be any sequence suitable to obtain, after modulation, the desired different frequency components. The first predetermined data sequence T1 may for instance include two or more different symbols and a transition between two successive symbols may correspond in the first signal part S1 with a first phase shift φ1 in a first direction and the second predetermined data sequence T2 may include two or more different symbols. A transition between a symbol to a following symbol may correspond to a second phase shift φ2 in a second direction opposite to the first direction. The first and second phase shift φ1,φ2 may for example be of the same magnitude but of opposite direction, or be of different magnitudes.
The first predetermined data sequence T1 and the second predetermined data sequence T2 may each include three, four, five or more symbols. In such a case, the first and second phase shift φ1,φ2 may have the same magnitude for each transition from a symbol to a following symbol. The first and second phase shifts φ1, φ2 may have any value suitable for the specific implementation and be in the range of larger than zero and smaller than 180 degrees. In case the test signal is a digital modulated signal, the sequences T1,T2 of symbols may be selected such that for each transition the modulated signal has a phase shift as close to 180 degrees as possible or instance, 3π/8-PSK the first and second phase shifts φ1, φ2 may be ±157.5 degrees, with a suitable margin of error. The margin of error may for example be below the error threshold at which it is no longer possible to distinguish different symbols from each other.
The test signal Stest may be any type of modulated signal suitable for the specific implementation. The test signal may for example be a digitally modulated signal, such as a phase shift keying modulated signal, an amplitude shift keying modulated signal or any other suitable type of signal. The test unit 1 or the transmitter 2 may include a modulating unit 21. Referring to the example of
in which relation n is a positive integer number smaller or equal to m, and k is an integer number. M may for example be a power of 2, for example 23 and p/q may for example be 3/8. The signal source may for instance be source of 8-PSK modulated signals with a 3π/8 offset, from hereon referred to as 3π/8-PSK.
The modulating unit 21 may receive a sequence of binary signals representing the first and second predetermined data sequence. Referring to
The mapping unit 211 may split the incoming sequence of binary data in 3-bit sequences and map the 3-bit sequences according to mapping information stored in a memory (not shown in
The mapping unit 211 may for example include a table which maps a n-bit binary sequences (n being an integer larger than or equal to 2) to a digital number. For instance, the table may map 3-bit sequences to decimal numbers q (e.g. integers in the ranged from 0 to 7). The table may further map the each of decimal numbers q to a specific digital modulation mode. For instance, the modulation scheme may be a phase shift keying scheme and the table may map each of the decimal numbers q to a corresponding phase (or phase shift) φq. For example, the modulation may be 8-PSK and the table may map each of the decimal number q (q being an integer in the range from 0 to 7), to a corresponding phase φq. The phases φq may for example be equally distributed and e.g. be spaced q*π/2n radians. The modulating unit 21 may for example, as shown in
The mapping unit 211 outputs a signal with the phase φq defined by the mapping information to a phase rotation unit 212. The phase rotation unit 212 may add a phase rotation to the outputted signal Stest (q), in order to shift the phase of the signal. For example, the phase rotation unit 212 may cause the signal outputted by the mapping unit 211 to have an additional phase shift of φoffset.
The phase rotation unit 212 may for example add an additional phase shift φoffset. The additional phase shift φoffset may for example change with each transition to a following symbol q, and for example be multiplied by an integer counter value which is increased for each transition. E.g. before a first transition the additional phase shift φoffset may be 0, after the first transition the additional phase shift φoffset may be a*π radians, after a second transition the additional phase shift φoffset may be 2*a*π radians, after a third transition the additional phase shift φoffset may be 3*a*π radians, etc.
The phase rotation unit 212 may output the phase rotated signal S(φq+φoffset) to a filter 213. The filter 213 may modify the phase rotated signal S(φq+φoffset) to have a desired frequency profile. For example, the filter 213 may be a Gaussian filter, such as a linearized Gaussian filter. For instance, the filter 213 may process the phase rotated signal S(φq+φoffset) in order to limit the frequency components in the phase rotated signal S(φq+φoffset) to a certain bandwidth. As shown in
The mixers 214,215 may mix the filtered signal Sf with a local oscillator (LO) signal. For instance in the example of
The mixers 214,215 may mix the filtered signal Sf with the first and second local oscillator signals LO(φ1), LO(φ2) respectively. Thereby, respectively an in phase (I) signal and an out-of-phase signal (e.g. a quadrature (Q) signal in case of a phase difference of π/2 radians) may be obtained. The mixers 214,215 may output the respective mixed signals to a combiner which combines the first signal LO(φ1) and second signal LO(φ2) into the, modulated, output signal Srf.
As shown in
It is found that when modulated with 3π/8-PSK method such a symbol sequence result in a modulated signal with distinct frequency characteristics which allow an accurate testing of the components 21,22 of the transmitter 2.
The invention may also be implemented in a computer program for running on a computer system, at least including code portions for performing steps of a method according to the invention when run on a programmable apparatus, such as a computer system or enabling a programmable apparatus to perform functions of a device or system according to the invention. Such a computer program may be provided on a data carrier, such as a CD-rom or diskette, stored with data loadable in a memory of a computer system, the data representing the computer program. The data carrier may further be a data connection, such as a telephone cable or a wireless connection. Such a computer program may for example be used to simulate the performance of one or more components of a transmitter or to test a design of such components.
In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims. For example, other modulation schemes may be used. Furthermore, the test unit 1 may be used to test transmitters that may be used in a telecommunication system, such as a mobile telephone network or any other suitable type of network
Also, the invention is not limited to physical devices or units implemented in non-programmable hardware but can also be applied in programmable devices or units able to perform the desired device functions by operating in accordance with suitable program code. Furthermore, the devices may be physically distributed over a number of apparatuses, while functionally operating as a single device. For example, the modulation unit 21 may be implemented as two or more semiconductor devices and include a separate local oscillator implemented on a different piece of semiconductor than e.g. the mapping unit.
Also, devices functionally forming separate devices may be integrated in a single physical device. For example, the modulation unit 21 and/or the power amplifier and/or the antenna 4 may be implemented in a single integrated circuit package.
However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.
In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘one or more’, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2006/055061 | 12/15/2006 | WO | 00 | 6/11/2009 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/072036 | 6/19/2008 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5943617 | Nakamura | Aug 1999 | A |
| 6486691 | Tsujii | Nov 2002 | B2 |
| 7652532 | Li et al. | Jan 2010 | B2 |
| 20080291987 | Kumaki et al. | Nov 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 0882994 | Dec 1998 | EP |
| 1513271 | Mar 2005 | EP |
| 03028248 | Apr 2003 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20100014570 A1 | Jan 2010 | US |
