KR20060094076A - Frame Synchronization Using Soft Decision in a Universal Mobile Phone System Receiver - Google Patents

Abstract

The universal mobile telephone system (UMTS) receiver performs frame synchronization according to a soft decision technique. By way of example, a UMTS receiver first forms a matrix of correlation peak values from at least one received frame (350), where each row represents a possible SSCH code, and each column represents a slot location of the SCH frame. Indicates. The UMTS receiver then forms 355 a metric for each cyclic shift of each of the 64 possible scrambling code groups from the matrix of correlation peak values, and identifies 360 the metric having the maximum value. If the maximum metric value has been identified, the UMTS receiver completes frame synchronization using the scrambling code group 365 and offset 370 associated with that value.

Description

FRAME SYNCHRONIZATION USING SOFT DECISIONS IN A UNIVERSAL MOBILE TELEPHONE SYSTEM RECEIVER}

FIELD OF THE INVENTION The present invention relates generally to wireless receiving devices, and more particularly, to user equipment (UE) in spread-spectrum based wireless systems such as universal mobile telephone systems (UMTS).

The basic time unit in a UMTS radio signal is a 10 ms radio frame divided into 15 slots of 2560 chips, respectively. The UMTS radio signal from the cell (or base station) to the UMTS receiver is referred to as the "downlink signal", while the radio signal in the reverse direction is referred to as the "uplink signal". When the UMTS receiver is first turned on, it performs a "cell search" to find a cell with which to communicate. In particular, as discussed below, the UMTS receiver looks for the downlink synchronization channel (SCH) initially transmitted from the cell and synchronizes to that channel at the slot and frame level, and determines the particular scrambling code group of this cell. Only after successful cell search can voice / data communication be initiated.

Regarding cell search, the SCH is a sparse downlink channel that is active only for the first 256 chips of each slot. This SCH consists of two subchannels, a first SCH (PSCH) and a second SCH (SSCH). The 256 chip sequence or PSCH code of the PSCH is the same in all slots of the SCH for all cells. In comparison, the 256-chip sequence or SSCH code of the SSCH is different in each of the 15 slots of the radio frame and is used to identify one of the 64 possible scrambling code groups. In other words, each SCH radio frame repeats a scrambling code group sequence associated with each transmission cell. Each SSCH code is derived from the alphabet of 16 possible SSCH codes.

As part of cell search, the UMTS receiver first uses the PSCH to achieve slot synchronization. In this regard, the UMTS receiver correlates received samples of the received PSCH for a 256 chip sequence of known PSCHs (same for all slots) and determines the slot reference time according to the position of the correlation peak. Once the slot reference time is determined, the UMTS receiver is slot synchronized and can determine when each slot will begin in the received radio frame.

After slot synchronization, the UMTS receiver stops processing the PSCH and starts processing the SSCH. As described above, the SSCH channel repeats a scrambling code group sequence associated with each transmission cell. As such, the UMTS receiver must first determine which of the 64 possible scrambling code groups is received, and then determine the number of slots in the offset between the estimate of frame initiation by the UMTS receiver and the actual frame initiation to synchronize the frame. Must be obtained. A typical approach is to use a hard decision technique. For example, the received signal is correlated for the 16 SSCH codes of the alphabet in each slot. The most strongly correlated SSCH code is used as an estimate of the received SSCH code for this slot. As a result, the 15 SSCH code estimates for the 15 slots are compared to all 15 possible shifts of all 64 possible scrambling code groups to identify the received scrambling code group and determine the frame offset (in UMTS, the scrambling code group The sequences are defined a priori so that their cyclic shifts are unique, that is, the cyclic shift of any scrambling code group sequence is not equal to any other scrambling code group sequence). Thereafter, the identification of the scrambling code group causes the UMTS receiver to descramble all of the remaining downlink channels (eg, Common Pilot Channel) (CPICH) in the cell to initiate voice / data communication.

Unfortunately, the SSCH portion of the cell search process described above is the most time consuming segment. In particular, due to the low signal-to-noise ratio at which the UMTS system may operate, the UMTS receiver processes a predetermined number of received radio frames, such as 10 to 20, to obtain a good estimate of the 15 SSCH code sequences transmitted from the cell. do. As such, since each radio frame is 10 ms long, a user may experience a delay such as at least 100 ms to 200 ms before being able to initiate voice / data communication.

Summary of the Invention

As mentioned above, the UMTS receiver processes the predetermined number of received radio frames to perform the SSCH portion of the cell search. However, using a hard decision technique to determine the received SSCH code in a particular slot means that if a determination is made as to which SSCH code was received in a particular slot, then the information about other received SSCH codes in that slot is probably As it is discarded, it can be seen that some performance degradation can occur under stringent channel conditions. For example, the hard decision technique selects the SSCH code associated with the maximum correlation peak. As such, if the received signal is compared to one of the 16 possible SSCH codes, the maximum correlation peak is 1025, and the next highest correlation peak (and possibly the peak associated with the correct SSCH code) is 1020, Later information about the SSCH code is discarded. As such, in some situations, particularly when operating under stringent channel conditions, an incorrect SSCH code is identified when received by a wireless receiver.

Thus, in accordance with the principles of the present invention, a wireless receiver receives a synchronization word comprising a plurality of codewords or symbols over a plurality of time slots, wherein the S symbols are associated with one synchronization word obtained from a set of M synchronization words. Associated, S > 1 and M > 1, the associated synchronization word is estimated as a function of metric values associated with each of the M synchronization words to obtain frame synchronization for multiple time slots.

According to one embodiment of the invention, a UMTS receiver is part of a UMTS user equipment (UE) and includes a processor and its associated memory. This processor first performs slot synchronization using the PSCH. After achieving slot synchronization, the processor performs frame synchronization by forming a matrix of correlated peak values from at least one received frame in its associated memory, where each row represents a possible SSCH code and each column Represents the slot position of the SCH frame. The processor then forms a metric for each cyclic shift of each of the 64 possible scrambling code groups from the matrix of correlation peak values and identifies the metric having the maximum metric value. Once the processor has identified the maximum metric value, it completes frame synchronization using the scrambling code group and offset associated with this value.

According to another embodiment of the present invention, the UMTS receiver performs frame synchronization according to the soft decision method. By way of example, a UMTS receiver first forms a matrix of correlation peak values from at least one received frame, where each row represents a possible SSCH code and each column represents a slot location of the SCH frame. The UMTS receiver then forms a metric for each cyclic shift of each of the 64 possible scrambling code groups from the matrix of correlation peak values and identifies the metric having the maximum value. Once the UMTS receiver has identified the maximum metric value, it completes frame synchronization using the scrambling code group and offset associated with this value.

1 illustrates a portion of an exemplary wireless communication system in accordance with the principles of the present invention.

2 and 3 illustrate an embodiment of a wireless receiver in accordance with the principles of the invention.

4 shows an example of a flowchart in accordance with the principles of the invention;

5 illustrates an embodiment of a correlator structure in accordance with the principles of the invention;

6 shows an example of a matrix structure for storing correlator values in accordance with the principles of the present invention.

7 shows another example of a flowchart in accordance with the principles of the invention;

8 shows an example of a metric matrix structure in accordance with the principles of the invention;

9, 10 and 11 further illustrate the matrix of FIGS. 6 and 8.

12 illustrates an example of a pseudo code implementation in accordance with the principles of the present invention.

13 and 14 show examples of simulation results.

Unlike the concept of the invention, the components shown in the figures are well known and will not be described in detail. In addition, the UMTS-based wireless communication system is also assumed to be familiar and thus will not be described in detail herein. For example, contrary to the concept of the present invention, spread spectrum transmission and reception, cell (base station), user equipment (UE), downlink channel, uplink channel and RAKE receiver are well known and are not described in detail herein. In addition, the inventive concept may be implemented using conventional programming techniques that will not be described in detail herein. Finally, like reference numerals in the drawings indicate like elements.

An exemplary portion of a UMTS wireless communication system 10 in accordance with the principles of the present invention is shown in FIG. The cell (or base station) 15 broadcasts a downlink synchronization channel (SCH) signal 16 including the aforementioned PSCH and SSCH subchannels. As mentioned above, the SCH signal 16 is used by the UMTS user equipment (UE) for synchronization as a precondition for voice / data communication. For example, the UE processes the SCH signal during a "cell search" operation. In this example, the UE 20, for example a mobile phone, initiates cell search when the UE 20 is turned on or powered up. The purpose of the cell search operation includes (a) determination of the scrambling code group of a cell (eg, cell 15) and (b) synchronization for cell transmission at the slot and frame level of a UMTS radio frame. As described below, in accordance with the principles of the present invention, the UE 20 uses a soft decision technique to determine a group of scrambling codes and to obtain frame synchronization. The following examples illustrate the concept of the present invention in relation to this initial cell search, i.e., when the UE 20 is turned on, but the concept of the present invention is not limited to such a case, but is not limited to other instances of cell search, such as Note that it may also be applied to other instances, such as when the UE is in "idle mode".

Referring now to FIG. 2, an exemplary block diagram of a portion of a UE 20 in accordance with the principles of the present invention is shown. UE 20 includes front end 105, analog-to-digital (A / D) converter 110, cell search element 115, searcher element 120, RAKE receiver 125, host interface block 130, and A processor 135. It should also be noted that, contrary to the concept of the present invention, additional elements that may be included in the block shown in FIG. 2 are well known in the art and are not described herein for brevity. For example, the A / D converter 110 may include a digital filter, a buffer, and the like.

The front end 105 receives a radio frequency (RF) signal 101 transmitted from the cell 15 (FIG. 1) via an antenna (not shown) and provides a baseband analog signal (e.g., a baseband analog signal) representing the PSCH and SSCH subchannels. 106). The baseband analog signal 106 is sampled by the A / D converter 110 providing a received sample stream 111. This received sample 111 may be used for three components: cell search element 115, searcher element 120, and RAKE receiver 125. The cell search element 115 further processes the PSCH and SSCH subchannels in accordance with the principles of the present invention as described further below. Following a successful cell search, the searcher element 120 may combine data from multiple paths, for example when providing a symbol for subsequent decoding by a decoder (not shown) to provide voice / data communication. Evaluate the received samples to assign a multipath to each finger of the RAKE receiver 125 which is present. Since only cell search element 115 relates to the concepts of the present invention, searcher element 120 and RAKE receiver 125 are not further described herein. The host interface block 130 combines the data between the three components described above and the processor 135, which receives the results from the cell search component 115 via signaling 134. Processor 135 is, for example, a storage program controller processor, such as a microprocessor, and includes memory 140 for storing programs and data.

Referring now to FIG. 3, an exemplary block diagram of cell search element 115 is shown. The cell search element 115 includes a PSCH element 205 and an SSCH element 210. In addition, reference should be made to FIG. 4 showing an exemplary flow chart in accordance with the principles of the present invention for processing the downlink PSCH and SSCH subchannels into the cell search element 115 of FIG. 3. The processor 135 of the UE 20 initiates cell search to process the downlink PSCH subchannel in step 305 to achieve slot synchronization. In particular, the processor 135 processes the received sample 111 by activating the PSCH element 205 via signaling 206 as known in the art. For example, because the downlink PSCH subchannel is a known PSCH 256 chip sequence or PSCH code that occurs periodically (i.e., repeating every slot of the downlink SCH signal), the PSCH element 205 may receive the received sample 111 PSCH. Correlate against the code and provide an associated peak correlation value. In this regard, the PSCH element 205 includes a match filter and a buffer (both not shown) that stores the output signal of the match filter. The PSCH element 205 provides the peak correlation value to the processor 135 via signaling 206. This peak correlation value may be averaged over several slots of the received radio frame (s), for example between 4 and 20 slots, to reduce the likelihood of "false lock" (PSCH synchronization is not a frame). Since using multiple slots, it is much faster than the SSCH frame synchronization of the prior art described above). If the peak correlation value is not greater than the preset threshold, processor 135 continues to control the PSCH element 305 to find the cell and continue processing for any received signal. However, if the peak correlation value is greater than the preset threshold, the UE 20 completes the slot synchronization. When the peak correlation value exceeds the next highest correlation value by a predetermined addition or multiplication factor, slot synchronization must be completed by another method.

If slot synchronization has been obtained in step 305, the UE 20 must determine which of the 64 scrambling code groups is used by the cell 15, with each scrambling code group being specific to 15 SSCH codes. Identified by the sequence. As used herein, the 64 scrambling code groups form a set of scrambling code groups. In forming a scrambling code group, each SSCH code or symbol is obtained from an alphabet of 16 symbols, for example from 1 to 16. As such, an exemplary scrambling code group, such as group 1, may include the following 15 SSCH symbols:

[1 1 2 8 9 10 15 8 10 16 2 7 15 7 16]. On the other hand, another scrambling code group, such as group 2, may include the following 15 SSCH symbols:

[1 1 5 16 7 3 14 16 3 10 5 12 14 12 10].

In accordance with the principles of the present invention, processor 135 determines the scrambling code group and obtains frame synchronization in accordance with the soft decision based technique in step 310 of FIG. In particular, as will be described further below, processor 135 forms a set of metrics (metric sets) for each of the scrambling code groups, each metric set being associated with a particular cyclic shift of each of the scrambling code groups. Contains the metric value. Thereafter, the processor 135 selects a maximum metric value from all metric sets. The particular metric set for which the maximum value is selected identifies the scrambling code group and the cyclic shift corresponding to the selected metric value and determines the frame offset to obtain frame synchronization. It should also be noted that for brevity, error conditions are not shown in the flowcharts described herein. For example, if slot synchronization fails while the UE 20 attempts frame synchronization, the cell search described above is unfortunately restarted.

According to one aspect of the invention, an exemplary structure for the SSCH element 210 is shown in FIG. 5. SSCH element 210 includes a correlator bank 220 and a memory 230 comprising K correlators from 220-1 to 220-K. Each correlator correlates the received sample 111 in a time slot to each of a plurality of codewords C ₁ to C _K. As such, correlator bank 220 provides K correlator values to memory 230 for each time slot. Memory 230 stores correlator values for S received time slots, ie, memory 230 stores S x K correlator values. Note that other memories such as, for example, memory 140 may also be used to store correlator values. By way of example, in this example, the codeword is an SSCH code with K = 16, i.e., there is one correlator for each possible value of the SSCH code with S = 15, and memory 230 stores the frame value of the correlator values. That is, it stores 240 values. As shown in FIG. 6, the storage of correlator values in memory 230 for a frame is schematically organized into a matrix or table 212 of correlator values. For simplicity, only the form of the matrix 212 is shown in FIG. 6, ie no actual correlator peak values are displayed in individual cells of the matrix 212. Each row of the matrix 212 corresponds to one of sixteen SSCH codes from SSCH 1 to SSCH 16, and each column corresponds to one of fifteen time slots from slot 1 to slot 15. In other words, each column stores correlator values that in fact represent a probability or confidence indication that a particular one of the SSCH codes has been received in that time slot. For example, if SSCH code 1 had a correlation peak of 1000 for a particular time slot, and SSCH code 2 had only 500 correlation peaks for the same time slot, then SSCH code 1 was sent in this time slot rather than SSCH code 2. I am more confident. Thus, in accordance with one aspect of the present invention, a matrix of correlator values collects / retains information related to all possible received SSCH codes for at least one frame, so as to operate the SSCH channel when operating under stringent channel conditions, as described below. Provides improved ability to acquire.

Referring now to FIG. 7, an exemplary flow chart in accordance with the principles of the present invention used to implement step 310 of FIG. 4 is shown. In particular, at step 350, the SSCH element 210 stores a plurality of correlation values for each of the possible received SSCH codes for at least one frame, i.e., 15 time slots, in the aforementioned matrix 212 of correlator values. (Note that multiple frame values of correlation data can be accumulated and stored in a matrix of correlator values). In step 355, the processor 135 accesses the memory 230 via the signaling path 211 of FIG. 3 and uses the values stored in the matrix of correlator values 212 to obtain a matrix or table of metric values. Matrix). An example metric matrix 213 is shown in FIG. 8. Again, for the sake of brevity, only the structure of the matrix 213 is shown in FIG. 8, ie no actual metric values are displayed in the individual cells of the matrix 213. Each row of the metric matrix corresponds to one group of preset scrambling code groups, and each column corresponds to a specific cyclic shift of this scrambling code group. As can be seen in FIG. 8, each entry in the metric matrix associates a metric value with a particular cyclic shift of a particular scrambling code group. Thus, each row of the metric matrix, ie each scrambling code group, is associated with a metric set that includes multiple metric values associated with different cyclic shifts of the scrambling code group with respect to group 64 as shown in FIG. . Processor 135 determines each metric value for a given shift of a given scrambling code group as the sum of the confidence values for this sequence. After the metric matrix is determined, at step 360, the processor 135 selects the maximum metric value in the metric matrix. Since each metric value is associated with a particular cyclic shift of a particular scrambling code group, processor 135 selects a scrambling group (ie, an associative row) associated with the maximum metric value at step 365, and at step 370. Determine the slot offset (ie associated column) associated with the maximum metric value to complete frame synchronization.

In addition, consider the following simple example: Assume that the SSCH code alphabet includes four codes or symbols {1, 2, 3, 4}, and the number of time slots per frame is two. In addition, the following scrambling code group

Group 1 = [1, 4]

Group 2 = [1, 2]

Group 3 = [3, 1]

Assume that group 4 = [2, 3] predefined. For example, from the above-described rule, group 1 is defined by SSCH symbol sequences 1 and 4.

As such, the SSCH element 210 includes four correlators in which each correlator compares the received sample 111 in a time slot to each of four possible symbols {1, 2, 3, 4}. According to step 350 of FIG. 7, SSCH element 210 stores a number of correlation peak values for each of the possible received SSCH codes in each of two time slots of the matrix of correlator values. An example matrix of correlator values for two particular time slots is shown in FIG. 9. As can be seen in FIG. 9, for symbol 1, a correlator value of 2 is associated with the likelihood that symbol 1 is received in a first time slot, while a correlator value of 7 indicates that symbol 1 is received in a second time slot. Associated with the likelihood, etc. Then, according to step 355 of FIG. 7, the processor 135 forms a metric matrix for each scrambling code group as shown in FIG. For example, with respect to group 1, processor 135 first determines a metric associated with a cyclic shift of zero. This is done by referring to a matrix of correlator values and calculating the metric value of 8 by adding the correlator value 2 associated with symbol 1 in the first time slot to the correlator value 6 associated with symbol 4 in the second time slot. do. This calculation is further illustrated in FIG. 11. Processor 135 then determines the remaining metric values in a similar manner. For example, with respect to group 1, the metric associated with the cyclic shift of 1, the likelihood that the received sequence is actually [4, 1] corresponds to 10, and so on.

Continuing with this example and referring to FIG. 7, after the metric matrix is determined, at step 360, the processor 135 selects the maximum metric value in the metric matrix. In this example, this value is 33. As can be seen in FIG. 10, the value 33 corresponds to the row associated with group 4 and the column associated with shift of zero. Accordingly, processor 135 selects group 4 as the scrambling code group in step 365 and determines that a shift of zero is required for frame synchronization in step 370.

If the SSCH processing was successfully completed in step 370, the identification of the scrambling code group of the cell 15 is determined by the UE 20 (used for frequency synchronization and also the actual scrambling code for the cell from the identified scrambling code group). Describing all other downlink channels of the cell (including, for example, a channel such as CPICH, used to determine), and voice / data communication may be initiated.

Referring now to FIG. 12, an example of a pseudo-code implementation in accordance with the principles of the present invention is shown. In the pseudo code of FIG. 12, the rx_data notation is 256 samples received for a given slot, SSC [i, j] is the j th sample in the i th SSCH code, and group_seq is the sequence of all 64 possible scrambling code group sequences. Matrix lookup table, group is the identified transport code group, and offset is the frame slot offset.

13 and 14 show simulation results of a UMTS receiver in accordance with the principles of the present invention. Figure 13 shows the simulation results in the absence of noise. In Figure 13, these values represent the metric values of the metric matrix. Large peak 401 indicates the maximum metric value and identifies scrambling code group number 10 as having an offset of zero, which is the correct group and offset. In comparison, FIG. 14 shows simulation results in the case of very low signal-to-noise ratio. Again, in Figure 14 these values represent the metric values of the metric matrix. Large peak 402 represents the maximum metric value and identifies scrambling code group number 10 as having an offset of 0 which is the correct group and offset. Although the metric of FIG. 14 appears to be noisy, the maximum peak 402 is actually 11% higher than the next highest peak. It should be noted that in the same simulation as shown in FIG. 14, a typical hard decision algorithm failed and incorrectly identified group 2 as having an offset of one. Accordingly, the soft decision approach according to the inventive concept, unlike the hard decision based approach, under the strict channel conditions because the soft decision based approach described herein does not discard information or data regarding the possible SSCH codes. You can do better.

As noted above, in accordance with the principles of the present invention, a wireless receiver employs a soft decision based technique to determine a group of scrambling codes and to obtain frame synchronization. This soft decision based technique provides a method and apparatus for robust second cell search in a UMTS receiver. Moreover, although extra storage or memory space is required, this is exchanged for the fact that the wireless receiver has an improved ability to acquire an SSCH channel when operating under stringent channel conditions (eg, very low signal to noise ratio). Although the concept of the present invention has been described in connection with an initial cell search process, it may be applied to any portion of the wireless operation in which downlink channels, such as SSCH subchannels, are processed.

While the principles of the invention have been described above by way of example only, those skilled in the art will appreciate that many other arrangements may be devised that implement the principles of the invention and are within the spirit and scope of the invention, although not explicitly described herein. . For example, although these functional elements have been described in terms of individual functional elements, they may be implemented in one or more integrated circuits (ICs) and / or one or more storage program control processors (eg, microprocessors or digital signal processors (DSPs)). Similarly, the concepts of the present invention have been described with respect to UMTS-based systems, but can be applied to other communication systems. Accordingly, it should be understood that many modifications may be made to these embodiments and that other arrangements may be devised without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (14)

As a method for use in a wireless receiver, Receiving a signal 111 indicating S symbols for a plurality of time slots, wherein the S symbols are associated with a synchronization word obtained from a set of M synchronization words, and wherein S> 1 and M> 1; , Estimating (310) frame synchronization with respect to the plurality of time slots by estimating the associated synchronization word as a function of a metric value associated with each of the M synchronization words. The method of claim 1, The frame synchronization acquiring step Storing K correlator values for each time slot, each correlator value representing a correlation of each of the K possible received symbols with K > 1 and the received signal in one of the S time slots; , Determining a set of metrics for each of the M synchronization words from the stored correlator values; Selecting a maximum metric value from all of the determined sets of metrics; From the selected maximum metric value, (a) determine one word of the M synchronization words as an estimate of the received synchronization word, and (b) set a time slot offset to obtain frame synchronization for the plurality of time slots. Determining. The method of claim 2, Each of the M synchronization words comprises a unique symbol sequence, For each of the M synchronization words, determining the set of metrics is Performing S cyclic shifts of the synchronization word; For each cyclic shift, adding each correlator value associated with the symbol pattern in each of the S time slots to each other. The method of claim 1, Each symbol is a second synchronization channel (SSCH) symbol of a universal mobile telephone system (UMTS), and the M synchronization words are a sequence of 64 scrambling code groups. The method of claim 4, wherein Acquiring the frame synchronization Matrix of correlation peak values from the received synchronization word, each row of the matrix being associated with one symbol of a plurality of possible received SSCH symbols, each column of the matrix being associated with one slot of the plurality of time slots; Each correlator peak value represents a correlation between each of the plurality of possible received SSCH symbols and each of the S received symbols in a corresponding time slot; Forming a metric value for each cyclic shift of each of the 64 scrambling code groups from the matrix of correlation peak values; Identifying a maximum metric value, From the identified maximum metric value, (a) determine one of the 64 scrambling code group sequences as an estimate of the received synchronization word, and (b) use it to obtain frame synchronization for the plurality of time slots. Determining the associated cyclic shift. The method of claim 5, wherein Forming the metric value Forming a metric matrix in which each row is associated with one of the 64 scrambling code groups, each column being associated with a cyclic shift, Adding each corresponding correlator peak value associated with a particular cyclic shift of a particular scrambling code group to determine each metric value. A method for use in a universal mobile telephone system (UMTS) receiver, Receiving a signal indicating a second synchronization channel (SSCH) transmitted from a UMTS transmitter, wherein the SSCH transmits a sequence of S SSCH symbols for S time slots, the sequence being a scrambling code associated with the UMTS transmitter Associated with a group, wherein the scrambling code group is obtained from a set of 64 scrambling code groups; Storing data representing the probability that each of the K SSCH symbols, where K > 1, is received in each of the S time slots; Determining metric values from the stored data, respectively, the metric values representing a probability of receiving a particular cyclic shift of a particular group of the 64 scrambling code groups; Identifying a maximum metric value, From the maximum metric value (a) determine the associated scrambling code group as the scrambling code group of the UMTS transmitter, and (b) from the associated cyclic shift for use in obtaining frame synchronization for the S time slots. Determining a time slot offset. The method of claim 7, wherein The data storage step Correlating each of the K SSCH symbols with the received signal in each of the S time slots to provide K corresponding correlator values; Storing the K corresponding correlator values associated with each of the S time slots. Universal Mobile Phone System (UMTS) equipment, A second synchronization channel (SSCH) transmitted from a UMTS transmitter, wherein the SSCH transmits a sequence of S SSCH symbols for S time slots, the sequence associated with a scrambling code group associated with the UMTS transmitter and the scrambling code The group receives a wireless signal indicative of a set of 64 scrambling code groups, from which a front end 105 for providing a sample stream, A memory 230 for storing data representing the probability that each of the K SSCH symbols, wherein K > 1, is received in each of the S time slots; (a) determining, from the stored data, metric values representing the probability of receiving a particular cyclic shift of a particular one of the 64 groups of scrambling code from the stored data, (b) identifying a maximum metric value, and (c) the maximum From the metric value, (1) determine the associated scrambling code group as the scrambling code group of the UMTS transmitter, and (2) time slot from the associated cyclic shift for use in obtaining frame synchronization for the S time slots. Universal mobile telephone system equipment comprising a processor (135) for determining an offset. The method of claim 9, The data representing the probability is a correlator value, (a) correlating each of the K SSCH symbols with the sample associated with each of the S time slots to provide K corresponding correlator values, and (b) the S time slots. And a correlator bank for storing the K corresponding correlator values associated with each in the memory. The method of claim 10, And the processor adds respective correlator values associated with the symbol pattern in each of the S time slots to determine the metric value of each particular cyclic shift of the scrambling code group. An apparatus for use in a wireless receiver, A front end for receiving and providing a sample stream therefrom, the frame signal, wherein each frame transmits a symbol sequence for a plurality of time slots, the sequence a priori associated with a source of the radio signal; 105, A memory 140 for storing a table of metric values, each row associated with one of the M synchronization symbol sequences, where M > 1, and each column associated with a cyclic shift of the M sequences; (a) identifying a maximum metric value stored in a table of metric values, (b) from the identified maximum metric value (1) determining one of the M synchronization symbol sequences as an estimate of the received symbol sequence, (2) a processor (135) for determining the associated cyclic shift for use in obtaining frame synchronization for the received wireless signal. The method of claim 12, Further comprising a memory 230 for storing a table of correlation values, each row associated with one of a plurality of possible received symbols, each column associated with one of the plurality of time slots, Each correlation value represents a correlation between each of the plurality of possible received symbols and the sample in a corresponding time slot, wherein the table of metric values is derived from the table of correlation values. The method of claim 13, And the processor adds respective correlation values associated with the symbol pattern in each of the S time slots to each other to determine the stored metric value of each particular cyclic shift of each of the M sequences.

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