GB2432483A

GB2432483A - Testing of paging in a mobile network

Info

Publication number: GB2432483A
Application number: GB0523546A
Authority: GB
Inventors: Gopikrishna Charipadi
Original assignee: Ubinetics VPT Ltd
Current assignee: Ubinetics VPT Ltd
Priority date: 2005-11-18
Filing date: 2005-11-18
Publication date: 2007-05-23
Anticipated expiration: 2025-11-18
Also published as: GB2432483A8; GB2432483B; GB0523546D0

Abstract

A series of paging channel frames for use in testing a mobile communication receiver's response to paging are generated according to the following equation: <EMI ID=1.1 HE=15 WI=139 LX=257 LY=837 TI=MF> <PC>where q is the paging indicator position, sfn = sfni + (k*D) and k is integer and the method comprises producing q values from said equation with D = 1 and sfni = 0 for eight consecutive values of k commencing with a value of k having the property k mod 8 = 0 and using the q values thus produced as paging indicator positions for said frames. The testing may be particularly applicable in UMTS networks.

Description

P106770GB TESTiNG OF PACING This invention relates to identifying

paging indicator positions suitable for use in a test signal for a communications receiver and to testing a communications receiver using paging indicator positions thus identified.

In a UMTS (Universal Mobile Telecommunications System) network, a UE (User Equipment) must monitor the PICH (Paging Indicator Channel) for a paging flag indicating that there is an incoming call for that UE. A UE will not, however, monitor the PICH channel continuously since the UTRAN (UMTS Terrestrial Radio Access Network) will configure the UE to monitor the PICH periodically. This periodic cycle is defined in the 3GPP (Third Generation Partnership Project) standards by the DRX (Discontinuous Reception) cycle which can range from 80 milliseconds to 5 seconds. The advantage of DRX reception is that during those periods when a UE is not required to monitor the PICH, it typically powers off its receiver and thus its battery life is conserved and stand-by time is enhanced. To configure a UE for discontinuous reception of PICH, the 3GPP standard defines four parameters, viz. Np, PT, sfn1 and DRX cycle length, as will be reviewed shortly.

According to one aspect, the invention provides a method of producing a series of paging indicator channel frames suitable for inclusion in a test signal, wherein each frame has a paging indicator position q given by the equation: q = (P1 +L((18*(s/n +Lsfi2 /8] +L.sfn /64] +Lsfii /512])) mod 144)*-]) mod Np where sfn = sfn1 + k * D and k is integer and the method comprises producing q values from said equation with D = I and sfn1 = 0 for eight consecutive values of k commencing with a value of k having the property k mod 8 = 0 and using the q values thus produced as paging indicator positions for said frames.

Hence, the invention can provide a test signal that can be used to test the ability of a UE to decode paging successfully.

By way of example only, certain embodiments of the invention will now be described by reference to the accompanying drawings, in which: Figure 1 illustrates schematically the UMTS PICH channel; and Figure 2 illustrates schematically a test harness that can be used to assess the operation of a UE.

The Paging Indicator Channel (PICH) that is used to carry the Paging Indicators has a radio frame structure as shown in Figure 1. It has a fixed-rate Spreading Factor of 256 and a radio frame time I of 10 ms. Each frame consists of 300 bits (b0, b1, b2... b299) of which the first 288 bits 2 are used to carry paging indicators and the last 12 bits 3 are not transmitted and are reserved for possible future use. The payload of 288 bits is used to transmit a paging indicator in one of Np positions.. Each paging indicator is of length of 288/Np bits and is equal to value 1 for paging and +1 for non-paging. According to the 3GPP standards, Np can assume a value of 18, 36, 72 or 144. The value of Np to be used by a UE is configured by the RAN (Radio Access Network) via a CPHY message, which is a message that configures the UE to start listening to paging indicators (the configuration sent in the message is: Np, PT, DRX cycle length, sfn1). It is important to note that if a PICH frame contains paging, it will be present in only one position, q, in that frame. This position is a function of sfn as explained in the next paragraph.

The position, q, of the paging indicator in a PICH frame is computed as follows by the following formula (reproduced from section 5.3.3.10 of 3GPP specification 25.211 (Release 5)): q =(PI+[((18*(sfn+[fn/8j+[sfn/64j+Lvth/512]))mod144)*iYj)modNp equation I In equation 1: * Np is the number of permitted paging indicator positions in the PICFI radio frame, and, as mentioned above, can assume only the values 18, 36, 72 and 144.

* P1 is a fixed offset which can assume any integer value in the range 0 to Np-i, inclusive. P1 is configured by the RAN (Radio Access Network) via a CPHY message and is assigned to a UE. The UTRAN network assigns a PT uniquely to the UE as part of the paging configuration.

* sfn is the System Frame Number of the P-CCPCH (Primary-Common Control Physical Channel) radio frame during which the start of the PICH radio frame occurs. The parameter sfn can assume any integer value between 0 to 4095, inclusive.

The parameter sfn is related to the DRX cycle length D through the equation: sfnsfn1+k*D -equation2 In equation 2: * sfn1 is the initial paging occasion and can assume any integer value in the range 0 to D-1, inclusive.

* k can take any integer value in the range 0 to 4096 -1, inclusive.

* D has the value 2 where n takes any integer value in the range 3 to 9 (3GPP defined), inclusive, thereby providing DRX cycle lengths from 80 ms to 5 s.

The inventor has observed that: * not all of the Np permitted q positions within the PICH radio frame are used for sending paging indicators to a UE.

* paging indicators are only sent in a subset of 8 of the permitted q positions in any PICH radio frame. The particular subset is selected by the value assigned to PT for a given Np.

Further, the inventor has found that: a cyclic 8-frame test vector with D = land sfn1 = 0 can generate this subset of 8 q-positions.

Examples

Four groups of examples, A-D, will now be presented to elaborate the above findings.

Group A: Np, P1 and sfn1 are kept constant at 18, 17 and 0, respectively, and changes to D are evaluated.

First, consider the case where D = 8. In this configuration, sfn = 0, 8, 16, 24 4080,4088, according to equation 2. That is, the paging indicators are present only in P-CCPCH system frame numbers which are a multiple of 8 starting from sfn1 =0.

A sample copy of the q positions computed by Equation 1 for P-CCPCH sfn = 0, 8, 16, 24, 32, 40, 48, 56 for the above configuration is reproduced in Table 1:

Table 1 _______ sfn q 0 17 8 1 16 3 24 5 32 8 10 18 12 56 14

If Table 1 were extended to all values of sfn, it would be apparent that the q column does not contain any values different from those presented in Table 1.

The inventor has found that the octet of q values of Table 1 can be generated by changing D from 8 to 1 as shown in Table 2: *fl 5,

Table 2 _______

sfn ______ 0 17 1 ___ 2 3 3 5 ___ 8 10 6 12 7 14 There is a one-to-one correspondence between Tables 1 and 2 in terms of the q positions.

Accordingly, the octet of q values formed when D=l will henceforth be referred as the basis set.

Next, consider the case where D is changed to 16, as shown in Table 3:

Table 3 _______

sfn ______ 0 17 16 3 32 8 _______ 12 64 1 5 96 10 112 14 If Table 3 were extended to all values of sfn, it would be apparent that the q column does not contain any values different from those of the basis set presented in Table 2.

Finally, Tables 4 and 5 show the cases where D = 256 and D = 512, respectively: fable 4 _______ Table 5 _______ sfn g sfn _______ 0 17 0 17 56 8 512 _______ 512 1 1024 3 768 10 1536 5 1024 3 2048 8 1280 12 2560 10 1536 5 3072 12 1792 14 3584 14 *fl 6 Again, if Tables 4 and 5 were extended, it would be apparent that the q columns do not contain any values different from those of the basis set presented in Table 2. The same result is also found for D = 32, 64 and 128. Accordingly, it can be concluded that the basis set for a given set of Np, P1 and sfn1 values is the same for all allowed values of D. Group B: Np, D and sfn1 are kept constant at 18, 8 and 0, respectively, and changes to PT are evaluated.

First, consider the case where P1=2. A sample set of the q positions for this configuration is shown in Table 6 and the basis set that would be obtained by changing D from 8 to 1 is

shown in Table 7:

fable 6 Table 7 _______ sfn 1q sfn _______ 0 2 0 2 8 4 1 4 16 6 2 6 24 8 3 8 32 11 ______ 11 1.0 13 5 13 1.8 15 6 15 56 17 7 17 It can be seen that the q positions in Table 6 correspond to the q positions in Table 7. If Table 6 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of

Table 7.

Consider now the case where P1 = 0. A sample set of the q positions for this configuration is shown in Table 8 and the basis set that would be obtained by changing D from 8 to I is

shown in Table 9: *fl 7

fable 8 _______ Table 9 _______ sfn q sfn _______ 0 0 0 0 8 2 1 2 16 ______ 2 4 _______ 6 3 6 32 9 4 9 ______ 11 5 11 ______ 13 6 13 56 15 7 15 It can be seen that the q positions in Table 8 correspond to the q positions in Table 9. If Table 8 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of

Table 9.

Thus there is a basis set of q-positions given by D = 1 for any given value of PT.

Group C: PT, D and sfn1 are kept constant at 19, 32 and 0, respectively, and changes to Np are evaluated.

First, consider the case where Np = 36. A sample set of the q positions for this configuration is shown in Table 10 and the basis set that would be obtained by changing D from 32 to 1 is shown in Table 11: fable 10 _______ Table 11 _______ sfn q sfn _______ 0 19 0 19 32 1 1 23 64 23 2 28 96 5 3 32 128 28 ______ 1 10 5 5 192 32 6 10 1224 14 7 14 It can be seen that the q positions in Table 10 correspond to the q positions in Table 11. If Table 10 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of

Table 11.

Now consider the case where Np = 72. A sample set of the q positions for this configuration is shown in Table 12 and the basis set that would be obtained by changing D from 32 to 1 is shown in Table 13: fable 12 ______ Table 13 _______ sfn q sfn _______ 0 19 0 19 32 55 1 28 64 28 2 37 96 64 3 46 128 37 _______ 55 1 5 64 192 ______ 6 1 24 10 7 10 Again, it can be seen that the q positions in Table 12 correspond to the q positions in Table 13. If Table 12 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set

of Table 13.

Now consider the case where Np = 144. A sample set of the q positions for this configuration is shown in Table 14 and the basis set that would be obtained by changing D from 32 to I is shown in Table 15: rfable 14 ______ Table 15 _______ sfn g sfn _______ 0 19 0 19 32 91 1 37 64 37 2 55 96 109 3 73 128 55 1 91 127 5 109 192 73 6 127 24 1 7 1 It can be seen that the q positions in Table 14 correspond to the q positions in Table 15. If Table 14 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of

Table 15.

Hence, it can be concluded from the examples in Group C that there is a basis set of q-positions given by D = 1 for any given value of P1.

Group D: Pr, D and Np are kept constant at 143, 64 and 144 respectively, and changes to sfn1 are evaluated.

First, consider the case where sfn1 = 63. A sample set of the q positions for this configuration is shown in Table 16 and the basis set that would be obtained by changing D from 64 to 1 and sfn1 from 63 to 0 is shown in Table 17: ITable 16 ______ Table 17 ______ sfn q sfn q 63 107 0 143 127 125 1 17 191 143 2 35 255 17 3 53 319 35 4 71 383 53 5 89 147 71 6 107 511 89 7 125 It can be seen that the q positions in Table 16 correspond to the q positions in Table 17. If Table 16 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of Table 17. An important point to note here is that the basis-set is generated with sfn1 = 0 although the sfn1 we are testing for in this case is non-zero(63).

Now consider the case where sfn1 = 29. A sample set of the q positions for this configuration is shown in Table 18: *fl 10,

Table 18 sfn j

29 143 93 17 157 35 221 53 285 71 349 89 fl3 107 177 125 It can be seen that the q positions in Table 18 correspond to the q positions in the basis set given in Table 17 above. If Table 18 were extended to provide rows for all sfn values, then it would be apparent that its q column does not contain any values different from those presented in the basis set of Table 17.

Hence from the examples in Group D we can conclude that variation in sfn1 does not affect the basis set.

Figure 2 illustrates a test harness 20 that makes use of the "basis set" concept for testing whether a UE design responds correctly to the PICH. The test-harness 20 comprises a combination of hardware and software.

A PC (personal computer) 22 generates a test vector that is to be supplied to a UUT (unit under test) 24. The UUT 24 is typically a prototype UE. The test vector repeats cyclically and is 8 frames long. The test vector contains 8 frames of digitised samples of a number of composite chaimels viz., P-SCH, S-SCI-I, CPICH, P-CCPCH, PICH and SCCPCH. In practice, a UE first time-synchronises with P-SCH, then frame-synchronises with S-SCH, then cell-synchronises with CPICH, and finally synchronises with the network time-base by decoding the sfn in the P-CCPCH. Then finally, it decodes the PICI-I and if paging indication is present reads the paging information carried on the SCCPCH channel. The P-CCPCH and PICH are synchronised with different distinct values of time offset (including zero) which can be configured by the network and the time offset is defined by 3GPP standards. Accordingly, the UE synchronises with the P-CCPCH first and then applies the time offset to synchronise with the PICH. fl 11

In addition to our channel of interest, PICH, the test vector has supporting common channels like P-SCH, S-SCH, CPICH, P-CCPCH and P-SCCPCH channel that carries the associated paging transport channel (Pd). . These common channels are necessary to allow the UUT 24 to achieve time, frequency and cell synchronisation.

The PC 22 provides a test vector with the PICH channel configured with values for the parameters Np, P1 and with D and sfni equal to 1 and 0, respectively. In addition, the PICH channel is configured with standard 3GPP physical channel parameters (namely OVSF code, scrambling code and relative offset between PICH and P-CCPCH). Thus the PC can configure the PICH channel in the test vector to contain paging indicators in the basis set of eight q positions for any desired combination of Np and PT values. In other words, the PICH channel in each of the eight frames of the cyclically repeating test vector, contains paging indicator in one distinct (but different) q position of the basis set specified by the selected Np and P1 values.

The output of the test vector generation software in the PC 22 is a cyclic, eight frame, over sampled, base band test vector in a.wv file format. This.wv format file is directly downloaded via a connection 26 into a Rhode & Schwartz AMIQ 28 which generates I and Q analog QPSK (quadrature phase shift keying) base band outputs 30 and 32, respectively.

These I and Q signals are provided to a Rhode & Schwartz SMIQ 34 which is configured as a vector generator to generate a 3GPP standard RF output signal at 2.14GHz with 5MHz bandwidth. It should be noted that the SMIQ 34 is synchronised to the clock (not shown) of the AMIQ 28 as indicated by connection 36. The RF signal produced by the SMIQ 34 is provided via a connection 37 to the UUT 24. The UUT 24 is a UE reference design.

(Typically, before a chip is made for a phone, its functionality is proven to work on a prototype called a reference design. The working reference design is then taped to form a chip which finally handset manufacturers use in their commercial phones.) The UE reference design contains physical layer software for decoding physical channels in the output of the SMIQ 34, including the PICH.

The PC 22 acts as a RRC (Radio Resource Control-Layer 3) layer and configures the UUT 24 to receive different physical channels through a bi-directional interface 38. The PC 22 instructs the UUT 24 to receive the P-SCH, S-SCH, CPICH, P-CCPCH, PICH, S-CCPCH channels at different points in time. The PC 22 configures the UUT 24 these channels in the following order: P-SCH (to achieve time-synchronisation), S-Sd (to achieve frame synchronisation), CPICH (to achieve cell synchronisation), P-CCPCH (to read sfn to synchronise with network's time-base), PICH (to decode paging indicators) and S-CCPCH (to decode the Paging message, if any).

Now consider the case where the PC 22 sends via interface 38 a CPHY_PCH SETUP REQ to configure the UUT 24 to use the values 18, 3, 0 and 8 for Np, PT and sfn and d, respectively.

It is important to note that prior to configuring the UUT to decode the PICH, the UUT is configured to decode the system frame number sent on the BCH (broadcast channel) carried on the P-CCPCH physical channel of the test vector. As mentioned above, the PC 22 which acts as the RRC does the configuration. The PC 22 cannot configure the UUT 24 to decode PICH right away but first has to ensure that the UUT has synchronised itself (in time, frame and cell) with the test vector that is receiving. The UUT synchronisation to the test-vector is completed when the sfn in the BCH transport channel carried on the P-CCPCH is correctly decoded. At this point of time the PC 22 (RRC) is satisfied that the UUT 24 has synchronised to the test vector and will then configure the UUT to decode PICH channel. It is by decoding the system frame number that the UUT 24 achieves timing synchronisation with the AMIQ test vector radio frames and this is a prerequisite to being able to decode the PICH.

Table 19 below illustrates for various P-CCPCH system frame numbers the PICH q position that is computed by the UUT 24 and the q position that is used by the test vector at that P-CCPCH sfn. The right most column indicates whether the UUT 24 finds a paging indicator at the P-CCPCH system frame numbers concerned. A tick indicates that a paging indicator was found and a cross indicates that a paging indicator was not found. fl 13

Fable 19 ______________ P-CCPCH sfn UUT computed q Test vector sent q Page found? 0 3 3 ______ 8 5 3 X 16 7 3 X 24 9 3 X 32 12 3 X 14 3 X 48 16 3 X 56 0 3 X 64 5 3 X 72 7 3 X 9 3 X 88 12 3 X 96 14 3 X 104 16 3 X 112 0 3 X 3 3 ______________ 128 7 3 X 136 9 3 X 144 12 3 X 152 14 3 X 16 3 X 168 0 3 X 176 3 3 7 184 5 3 X 192 9 3 X 12 3 X 208 14 3 X 216 16 3 X 224 0 3 X 232 3 3 ______________ Since D=8 and sfn=0, the UUT will only inspect test vector frames that contain a paging indicator in PICH q position 3 because sfn1 and D for the test vector are 0 and 1 respectively. In other words, since the basis-set for this configuration is 3, 5, 7, 9, 12, 14, 16, 0, the test vector contains Paging Indicators in its PICH channel at q position: fl 14 3 in P-CCPCH frames 0, 8, 16, ... 8m.

in P-CCPCH frames 1, 9, 17, ... 1+8m.

7 in P-CCPCH frames 2, 10, 18, ... 2+8m.

0 in P-CCPCH frames 7, 15, 23, ... 7+8m.

where m is integer.

Thus, the test results shown in Table 19 above clearly demonstrate that the ability of the UUT to selectively decode paging indicators can be tested using a test vector based around the basis set concept.

Consider now the case where the UUT 24 is configured by the PC 22 with the PICH configuration where Np, PT, sfn and D have the values 18, 3, 0 and 512 (longest possible DRX period equal to 5 seconds) respectively. The PC 22 provides the AMIQ 28 with a test vector utilising the basis set where the parameters Np and PT are 1 8 and 3, respectively.

Table 20 below illustrates for various system frame numbers the PICH q values that are computed by the UUT 24 and the PICH q values that are used in the test vector. Again, the right most column indicates whether the UUT finds a paging indicator in the current frame of the test vector.

fable 20 _______________ P-CCPCH sfn UUT computed g Test vector sent g Page found? 0 3 3 V 512 5 3 X 1024 7 3 X 1536 9 3 X 2048 12 3 X 2560 14 3 X 3072 16 3 X 3584 0 3 X 0 3 3 V 512 5 3 X 1024 7 3 X 1536 9 3 X 2048 12 3 X 2560 14 3 X 3072 16 3 X 3584 0 3 X 0 3 3 V 512 5 3 X 1024 7 3 X 1536 9 3 X 2048 12 3 X 2560 14 3 X 3072 16 3 X 3584 0 3 X 0 3 3 V 512 5 3 X 1024 7 3 X 1536 9 3 X 2048 12 3 X 2560 14 3 X This time, the UUT 24 only finds a paging indicator when the P-CCPCH system frame number is 0. This is because at the other occasions when the UUT 24 examines the PICH channel, the UUT 24 is, on the basis of equations 1 and 2, looking for a paging indicator at a q position other than that which is currently used by the test vector.

Consider now the case where the UUT is configured with Np, P1, sfn1 and D as 72, 3, 0 and 512 respectively. In this situation, the PC 22 loads the AMIQ 28 with the test vector containing the basis set of q positions 3, 12, 21, 30, 39, 48, 57 and 66. Then the UUT 24 fl 16 would be detecting paging indicators at those system frame numbers where equation 1 specifies q to have the value 3.

Consider now the configuration where the UUT 24 is configured with the same values of Np, PT, D as the above paragraph but sfn1 is changed, i.e., Np, PT, sfn and D are 72, 3, 5 and 8 respectively. The basis set remains as 3, 12, 21, 30, 39, 48, 57 and 66 so the test vector is unchanged. However, the UUT 24 will now detect paging indicators at system frame numbers where equation 1 produces a q value of 48. In other words, sfn1 equal to 5 implies that the Paging Indicator in the 6th PICH frame of the basis set is always decoded by the UUT (Note: 1st PICH frame containing paging in q=3 corresponds to sfn1 0).

Table 21 below relates to the sfn1 = 5 case.

Fable 21 _______________ P-CCPCH sfn UUT computed q Test vector sent g Page found? 48 48 VI 13 57 48 X 21 66 48 X 29 3 48 X 37 12 48 X 21 48 X 53 30 48 X 61 39 48 X 69 57 48 X 77 66 48 X 3 48 X 93 12 48 X 101 21 48 X 109 30 48 X 117 39 48 X 48 48 VI 133 66 48 X 141 3 48 X 149 12 48 X 157 21 48 X 30 48 X 173 39 48 X 181 48 48 1' 189 57 48 X 197 3 48 X 205 12 48 X 213 21 48 X 221 30 48 X 229 39 48 X 237 48 48 VI

Claims

CLAIMS

1. A method of producing a series of paging indicator channel frames suitable for inclusion in a test signal, wherein each frame has a paging indicator position q given by the equation: q = (P1 + [((18* (sfn + [sfii / 8] + [.sfn / 64] + Lsfn / 512])) mod 144) * ]) mod Np where sfn = sfn1 + (k*D) and k is integer and the method comprises producing q values from said equation with D = 1 and sfn = 0 for eight consecutive values of k commencing with a value of k having the property k mod 8 0 and using the q values thus produced as paging indicator positions for said frames.

2. A test signal for testing the operation of a communications receiver, the test signal containing a series of paging channel frames produced by the method of claim 1.

3. A method of testing the operation of a communications receiver, the method comprising applying to the receiver a test signal according to claim 2 and observing the response.

4. A program for causing data processing apparatus to perform a method according to claim I or3.

5. Apparatus for producing a series of paging indicator channel frames suitable for inclusion in a test signal, wherein each frame has a paging indicator position q given by the equation: q = (P1 + [((I 8 * (sfn + Lsfn / 8] + [sfn / 64] + [sfn / 512])) mod 144) * ]) mod Np where sfn = sfn1 + (k*D) and k is integer and the apparatus comprises processing means for producing q values from said equation with D = I and sfn1 = 0 for eight consecutive values of k commencing with a value of k having the property k mod 8 = 0 and for using the q values thus produced as paging indicator positions for said frames.