TW393842B - Cell searching in a cdma communications system - Google Patents

Abstract

A special coding scheme is disclosed for more effectively acquiring a long code and frame timing during a cell search in a CDMA communications system. A code set of length M Q-ary code words including symbols from a set of Q-short codes is defined with certain properties. The primary property to be satisfied is that no cyclic shift of a code word yields a valid code word. The other properties to be satisfied are that there is a one-to-one mapping between a long code message and a valid code word. And a decoder should be able to find both the random shift (thereby implicitly finding the frame timing) and the transmitted code word (I.e., its associated long code indication message) in the presence of interference and noise, with some degree of accuracy and reasonable complexity.

Description

V. Description of the invention (1), related applications This patent application is a US patent No. 6 〇 Z 0 5 7, 4 1 2 filed on August 29, 1997 for reference only. BACKGROUND OF THE INVENTION Technical scope of the invention The present invention relates generally to the spread spectrum communication range, and more particularly to the cell-seeking action performed by a mobile station to obtain time synchronization with the base station and obtain multi-directional proximity in the cut code ( C DMA) special cell long code and frame timing information used in the communication system. Description of related techniques The commercial operation of the cellular telephone industry around the world has made amazing progress. Growth in major metropolitan areas has exceeded expectations, and the pursuit of greater system capacity = If this trend continues, the rapid growth of the daring fruit will soon be reached even in the smallest markets. The main problem related to this continued growth is customer-oriented positive expansion, and the amount of electromagnetic spectrum allocated to cellular service providers for carrier high frequencies continues to be limited. Innovative solutions need to meet these increasing capacities in the limited available spectrum, and maintain high-quality services and avoid price increases = At present, channel access in cellular systems is mainly using frequency-spanning multi-directional proximity (FDMA) ) And the time-division multi-directional proximity (TDMA) method is achieved = In the FD.MA system, the actual communication channel system includes a single radio frequency band, and the signal transmission power is specifically studied. In a TDMA system, the actual communication channel is the time slot in a periodic sequence of time intervals on certain radio frequencies. Although satisfactory efficiency is obtained from FDMA and TDMA communication systems, so

C: \ 123 / i \ 54505.ptd Page 5

Channel access methods that will be replaced due to increasing customer requirements are now being planned, considered, and implemented. This spectrum is a communication technology application that is currently looking for applications, and a new channel in j Communications. Access method. The first application of the spectrum reduction system in the second ^: ι is military-oriented (about

If Tiida satellite). However, the use of spread spectrum in other communication deer applications is gradually increasing today, including digital ^ surface mobile radios, and indoor / outdoor personal communications:-line power, ground spread = spectrum operation and traditional leg and ship communication systems Yes, they are. For example, in the direct sequence cdma (ds_cdm Tian Bumen, the exclusive or common operation on the basic symbol rate: extension? The transmitter is extended to the chip 帛. This extension operation is used when the = bit symbol stream: including the only channel extension Code (sometimes called complex: time, which is the symbol stream of its transmission rate (frequency band). Typical drop-in sequence) is used to increase the digital code that is multiplied when expanding. 衽: J-bit symbol stream (chip) The intermediate signal system will then be added to :: The food sequence is similar to the processing (ie, expansion) of the intermediate signal. The other categories are only 2 levels: making "Changma |", test, since in the majority of affection;;: code (Often. It is used to synthesize the interim signals so that the communication is two ^ yards) and then amuse the output signal of the transmission. The multi-frequency advantage associated with the exclusive / universal channel is that it will then share a round communication frequency. The multiple signals on the top of each other in the time domain and the time domain. "'·, Because of this, it is located in the frequency domain on the shared communication channel to use! Expand the editor like -W' and by receiving j : -Middle letter ~ application of field processing technology

C: ι'Ί234 \ 54505. Ptd page 6 5. Description of invention (3) It can be distinguished from others. In a DS-CDMA spread-spectrum mobile station receiver, the received signal is recovered by applying (ie, multiplying, or matching) the appropriate scramble and spreading codes in order to be non-spread, or removed From the encoding of the intended signal, and back to this basic symbol rate. However, when the spreading code is used for other transmission and reception intermediate signals, only noise is generated. This non-spreading operation can thus effectively include a correlation process that compares the received signal with an appropriate digital code in order to recover the desired information from the channel. Any radio frequency communication or message transmission between the base station and the spread spectrum communication system mobile station must be found by the mobile station and itself must be synchronized with the timing reference of that base station. This process is usually used as a reference for " cell search ". For example, in a DS-CDMA spread spectrum communication system, the mobile station must look for downlink chip boundaries, symbol boundaries, and frame boundaries for this timing reference clock. The most common solution implemented to solve this synchronization problem is a base station with a perceptual transmission (with repeating cycle Ty) as shown in Figure 1, a mobile station that can detect and process, and an identifiable Np chip. Synchronized 磉. The synchronization code is also referred to as the extension code of the long code mask symbol. The synchronization code is transmitted using known chirp modulation, and the target requires any scrambled long code. In a CDMR type communication system, each base station utilizes a known different synchronization code from a set of available synchronization codes. In another CDMA-type communication system, all base stations utilize the same synchronization code by using a transmission synchronization code that is out of phase shift, which differs between the base stations to be identified. In a mobile's spread-spectrum receiver, the received signal is demodulated

C: \ 1234 \ 54505. Ptd page 7 ------ 5. Description of the invention (4) Change ‘and use + mobile association :; a filter that matches the sync code. Of course, I understand Laoshan such as state peaks. Cool reason. In accordance with the filtering heavy path = access & relative to the transmission of the round synchronization code periodically. As much related. As a result, the detection of several peaks is processed in a time-series manner related to single-synchronization code transmission. Among these reception peaks, 'repeated cycles with the transmitting base station can be sent;: 1 is not: indeed equal to the repetition period I if Synchronization related to this sequence :: if its: The seizure sequence reference can be used to communicate with the frame when it is in operation with the base station. The transmission synchronization code prepared in the chip is used as an actual event on the chip; second-hand; the complicated hands that are implemented in the time-receiver and compatible with the receiver =; to the mobile station to cause other spread spectrum In order to transmit the signal, the same length of the chip of Numu: interference. If it will become the average permissible injury power in the CDMA communication system, it will be shorter than the frame length of the household T, which is shorter than the size of the frame T—using the short step Tf as described in FIG. 2 Code repeats week. In the previous frame length T, the medium used to transmit the signal is to support the frequency in a compressed mode; a 5 V, 'one reason ik φ ^ L downlink synchronization' is just like the technology The downstream edge 蹊 η + Β σ ϋ, i5 k-type processing, and the line synchronization is set on the provided carrier frequency, only during the frame period of the frame. Then, you can use every two-to-two positive, and the conversion process will be completely missed at the obvious time of the time code. 7 Multiple transmissions during the first frame of the same transmission are used for the same purpose, with two: 2 yards cr can provide up to Russia s for each armature, which is used to suppress the "Dan-style processing detection ^ ^. Bureau, And at least one sync code transmission

'I234 \ 54505.ptd 苐 8 pages

5. Description of the invention (5) Enough detection. However, there are disadvantages with regard to the reception and synchronization of multiple sync codes & transmission in a single frame length Tf. Furthermore, the received signals are demodulated and a filter (or correlator) that conforms to a known synchronization code is applied. The output corresponding to the peak value of the filter is relative to the reception of a periodic transmission synchronization code. From processing these peaks, the timing reference of the transmission base Δ related to the synchronization code repetition period & can be found in known methods. However, this timing parameter is not explicitly related to the frame timing, and thus does not provide sufficient funding ‘: synchronize the base / mobile frame to the timing reference. Under ambiguity, the boundary of = wide means its synchronization) cannot be detected from the synchronization V alone; the cell search process also includes obtaining a special code in the downlink to scramble the exclusive and usual channel communication. f, the cells used in particular include routing and control channels, and the usual ... and other exclusive channel system channels (which can include broadcast control channels or Bcc 1 also include routing and control Cu:,. Ideally, such as ^ + —Changma it group code-crossing) transmission described in FIG. 3. This long code group code uses the known 5 ': two: step (and also needs any long-disturbed long code. Each long code group code ζ is transmitted by two branches without special subgroups. These long The code system is used to transmit the entire two sets of long codes. There are 128 long code systems in each—with 39 hi-hat heads. For example, do n’t send a long code group with the code -C | (| Four, code. Narrow down to include in the subgroup by shortcode search. 3 In this example, the long code can be identified by the received long code group code. 32 long code, and this subgroup Yes frame timing information can be found from the received sync code long code group descriptor

5. Description of the invention (6) to. Line signal and close time slot. Phase code group Each number of special codes is used for phase shift. Together with the sequence determination, the mobile station will first identify the timing of the synchronizing code by applying a transition device that conforms to the identified peak. The timing references in these peak reports can be found. Although S is correct at the time of the frame: = When the Chen position is fixed, the long code group code ΐ ΐει is transmitted at the same time. The correlation will then be performed at a known time slot position, so that Changma 5ci identification = From this confirmation, the possible fineness and number for transmission will be reduced. Finally, the correlation will be long code (ie, the long code included in the ilci recognition subgroup) on each known time slot & perform less to determine which cell special long code system is used for transmission, and improve Bit reference. Once the phase shift is found, the frame timing will be identified. Multiple sync codes & transmission in a single frame length η. The frame can be disclosed in U.S. Patent Case No. 08/8 84, 0 02, which was filed on June 27, 1997. The name is " m0bile STATION SYNCHRONIZATION WITHIN A SPREAD SPECTRUM COMMUNICATIONS SYSTEM ", and each time slot includes not only the synchronization code d 'as shown in Fig. 2 above, but also a frame synchronization code transmitted using a known modulation;' Instead of using a scrambled long code as described in Figure 4. The synchronization code is the same in each time slot and spans the repeated frames. However, each of the frame synchronization codes in the frame A time slot is unique and repeats in every frame. To obtain frame timing information, the mobile station must first confirm the synchronization code timing by applying a compatible modem to receive signals and identify synchronization. ^ Among these peaks, the timing reference related to these time slots can be found. When this timing reference is not clear in the frame timing, the knowledge of the time slot position will be

V. Description of the invention (7) Pointing to the position of the frame synchronization code in each positioning slot. The mobile station then further associates the known frame sync code tile with the received signal at the position of the frame sync code. Assuming that each frame sync code I about the frame boundary is known, once the correlation is found at the location, the frame boundary about it (and therefore the frame timing) will then also be known. Although previous methods used to obtain synchronization information provide satisfactory results, efficiency in the radio case is highly desirable. Inevitably, in all the above-mentioned prior art processes, poor radio link conditions and higher than normal interference levels can cause mobile stations to make incorrect decisions on long codes or frames, or both. As a result, having to perform additional interrelationships with value processing resources is a complex implementation and reduces cell search processing. Essentially, more signal energy can be collected by receiving signals over more frame periods. However, this method will take longer than the acceptable time for handover. Therefore, during a cell search process in a poor radio environment, there is a need for an effective method of obtaining frame timing indications and long code indications. As described in detail below, the present invention provides such a method. SUMMARY OF THE INVENTION Essentially, according to the present invention, the method is provided by using a special coding method to obtain the long code and frame timing more efficiently during the cell search. The length of the MQ-a r y codeword group including a short code symbol from a group of Q is defined to have certain characteristics. The main characteristic to be satisfied is that a cyclic shift without a codeword will produce a valid codeword. Another characteristic to be satisfied is that there is a one-to-one mapping between long code messages and valid codewords, and the decoder should be able to find arbitrary shifts in interference and noise with some accuracy and reasonable complexity. Bit (by

C: 1234 \ 54505.ptd Page 11 V. Description of the Invention (8) implies to find the frame timing) and the transmitted codeword (that is, combined with the long code indication message). '' An important technical advantage of the present invention is that it provides a low-complexity solution that can effectively obtain long codes and frame timing during cell search, and the coding gain provided by it can be used to reduce search time and / or required Information bit energy to noise ratio (E b / N 0). Another important technical advantage of the present invention is that it can effectively deal with the relationship between complexity and efficiency, and keep the number of possible messages fixed by changing the complexity of the code. However, another important technical advantage of the present invention is that it provides more codewords than traditional methods, which can reduce and / or limit the number of base station messages required. A brief description of the drawings is provided below in conjunction with the detailed description of the drawings to fully understand the method and device of the present invention, in which:-Figure 1 depicts a prior art synchronization channel in a direct sequence cutting code multi-directional proximity communication system Signal transmission format diagram; Figure 2 depicts another prior art synchronous channel signal transmission format diagram in a direct sequence cutting code multi-directional proximity communication system; Figure 3 depicts another diagram in a direct sequence cutting code multi-directional proximity communication system Prior art synchronization channel and long code group signal transmission format diagram; FIG. 4 is a diagram describing another prior art synchronization code and frame synchronization code transmission format in a direct sequence cutting code multi-directional proximity communication system; FIG. 5 is a diagram describing Used to implement the operation of the transmitter and receiver of the present invention

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V. Description of the invention (9) Figure; Figure 6 is a general diagram of a general decoding rule system for receiving and decoding a decoder according to a preferred embodiment of the present invention. The field description i is used for receiving the codewords related to Figure 5 above: and the receiving decoder It is used to explain FIG. 7 according to the second specific embodiment of the present invention ... The general maximum possible decoding of the receiving decoder _ * This can be used in the receiving decoder system to decode the existing hand: system flowchart 'and this The above shirt related to FIG. 5: Heart ring / bit interference / noise, and it shows the interleaving of the ^ 2 interlace encoder in order to clearly describe the present invention; Exemplary diagram, which provides a description of the invention; Clever] Female β 疋 FIG. 10 is a flowchart of an example of a regular system that can be used by an encoder to generate all words that can satisfy the characteristic 2 of the invention: / FIG. 11 describes a synchronization code , Which is caused by the implementation of the encoding rule system described in FIG. 10; FIG. 12 is an exemplary flowchart for decoding the above-mentioned synchronization code related to FIG. 11 according to the present invention; and FIG. 13 shows the description in FIG. 12 Mat 1 a of the synchronization code search rule system b List; Figure 14 shows some basic synchronization codes with small _ \ 丨 values; Figures 15 A and 15 B are block diagrams of examples of interleaved encoders that can be used to implement the present invention; Figure 16 depicts actions by The diagram of the cellular search method performed by the platform is like

C: \ 1234X54505.ptd Page 13 V. Description of the invention (10) ARIB broadband CDMA proposal in the prior art; Figure 17 is a table describing some characteristics of the primary synchronization code and the secondary secondary synchronization code; Figure 18 is according to the invention The information provided by the primary synchronization code or the secondary synchronization code of the cell search is shown: FIG. 19 is an example of the primary synchronization code and the secondary synchronization code used in the cell search shown in FIG. 18 according to the present invention. Method: FIG. 20 is a second example method provided in FIG. 18 showing the primary synchronization code and the secondary synchronization code for cell search according to the present invention. FIG. 21 is a description of two methods that can be used to implement the present invention. A table of cell search rule systems (methods), and also provides a comparison of the two cell search methods with the current ARIB broadband CDMA cell search proposals; Figure 2 2 depicts the rule system that can be used to compare the rules shown in Figure 21 ( Method) A comparison table; and FIG. 23 AD is a table describing the advantages of the two-cell search method of the present invention on the proposed ARIB broadband CDMA cell search method. DETAILED DESCRIPTION OF THE DRAWINGS The preferred embodiments of the present invention and its advantages can be better understood by reference to Figure 23D. The numerals are used on similar and opposite parts of various drawings. Essentially, according to the present invention, the method is to provide more efficient access to long codes and frame timing during the cell search by using special coding methods. A set of length MQ-ary codewords including a set of Q short code symbols is defined to have certain characteristics. The main characteristic to be satisfied is that a cyclic shift without a codeword will produce a valid codeword. Other characteristics to be satisfied are in long code messages and valid

C: \ i234 \ 54505.ptd Page 丨 4 V. Description of the invention (11) There is a one-to-one mapping between codewords, and the decoder should be capable of interference and noise with certain accuracy and reasonable complexity. To find arbitrary shifts (to imply frame timing) and transmission codewords (ie, combined with long code indication messages). More specifically, to describe the environment, it is assumed that the transmitter transmits M symbols selected from Q-ary letters (eg, Q orthogonal short code letters including a length N). These transmitted symbols constitute a transmission codeword, and a length M Q-a r y sequence (codeword) group can be used as a code reference. Similarly, the same codeword is retransmitted. The receiver (the receiver of these transmitted codewords) will know when the symbol is suitable to start and stop, not when the codeword starts and stops. Similarly, the transmitted signal is subject to decay, interference, and noise. Similarly, the purpose of the receiver is to (1) potentially obtain the transmitted code (and relative information) without requiring significant knowledge of its start / stop time, and (2) obtain the start of such codewords / Stop time. Figure 5 is a diagram illustrating the operation of the transmitter and receiver directly described above. Please refer to FIG. 5, the transmission symbols are represented by a, b, c, etc. Note that in this example, the symbols a, b, c, and d are equal to the symbols f, g, h, and i, respectively, due to the periodic transmission of signals. Similarly, it should be noted that any group of M consecutive symbols includes all the information required by the receiver to decode the received signal, assuming that the receiver knows the frame timing of the code. In this example, M is equal to 5. If the frame timing of the code is unknown, then the decoding process is important. However, in this example, the frame timing knowledge of the code is purely hypothetical, along with the use of codes with some known characteristics. On the receiver (R X), it can be seen that any group in the M = 5 shift is connected

C: U234 \ 54505. Ptd page 15 5. Description of the invention (12) The continuation symbol can include information used to decode the received signal. Obviously, for simplicity, it is assumed that the time interval between symbols is zero in the following description. As such, it can assume that traditional decoding methods are used to ensure that scrambled symbols relative to the codeword are obtained with acceptable reliability. Channels (from the receiver's perspective) can be said to introduce arbitrary symbol errors due to interference and noise, and interference and noise will shift codewords of any (full) number of Q-ary symbols. The transmitter repeatedly retransmits the same message. As a result, any received M consecutive symbols (regardless of their location) can represent the codeword until some unknown cyclic shift. Similarly, a block of length M Q-ary codewords (with symbols from a Q short code group) is defined with the following characteristics. Feature 1: There is a one-to-one mapping between the long code message and the valid codeword (with L codeword or message); Feature 2: The cyclic shift without codeword (Q-ary symbol cyclic shift) will produce Valid codewords (unless the number of shifts is zero or a multiple of M, which is an irrelevant solution); and characteristic 3: the decoder should be able to find arbitrary in interference and noise with ideal reasonable and complex accuracy (Which implicitly defines the frame timing) and the transmission codeword (that is, its combined long code message or LC I message). Obviously, as described in detail below, the preferred embodiment of the present invention uses codes that mainly satisfy characteristic 2. Also as described below, it follows that these codes also satisfy characteristics 1 and 3. First, to further understand the invention, consider the lack of

C: 1234X54505.ptd Page 16 V. Outline of the Invention (3) Channels where symbol errors occur (simplified), and only an unknown number of cyclic symbol shifts of unknown repeated transmission codewords will occur. The receiver must decide Shift and pass codewords. Figure 6 is a flowchart of a general decoding rule system that can be used in a receiver solution according to a preferred embodiment of the present invention, and the receiver decoder is used to Explain the above (although 坱 is not the rightmost *… ,: IL is not a method of taking% code with 乂). On step 101, the β decoder will collect continuous symbols (

Secondly, on step 102, the interpretation of the stele is combined with an effective 97 code. If it is not right, the code ^ will determine whether the received word is 1 0 3. No π, β Μ " scoop code, 5 Hai decoder will perform step 103 ... otherwise 's Hai decoder will perform step 104. i 〇 / 上; The word received by Shiguo is not a valid codeword. In the step back to the Λ code, the device will cycle-step (symbol) to shift the received word, and it will output the shifting wife ", At step 104, the resolver combines the codeword center to obtain the valid codeword from steps 1G3), and the number of shifts output at step 104 from generating two of the codeword is then == two? Two The specific embodiment describes a flowchart that can be used in the receiver decoder / decoder rule system '(however, it is not the same as the most arbitrary symbol / bit interference / noise body in the embodiment H㉟: method) The above codewords. Before the collection of k * M symbols, except before decoding the received words, the present invention will enable it to provide multiple copies of all the code symbols of the V-thest acquired code, which is used here :: A better codeword estimation. Example of the maximum possible decoder rule system,

C: M 23 ^ X54505. Ptd page 17 V. Description of the invention (14) ^ At step 201, the decoder will collect k * M consecutive symbols (received sub), and sub-combine symbols of these possible values. In step 202, for each of the "f" and M cyclic symbol shifts in f of the L code t, the? Code Yiyi will be shifted in the correlation such as Rong and so on. The interrelationship between the word and the relevant combination of the temple yard field. The decoder stores the codeword and the number of shifts caused by fetching and correlation. In step 203,: H2, the stored codeword (or relative information) and the number, and the number of shifts caused by the optimal correlation. From this aspect, it makes the system more effective—an effective decoding rule system. In essence, according to Yuan; Ni Erniu's current decoding rule system is a combination of the so-called trailing bit II, I code and synchronization code 'so that all the characteristics of Bili's code is through an internal interleaved code string with an outer code Connected by. ; Sex 1 and 3 are also satisfactory. Will be steep 2. In accordance with the special month, ^, according to the specific implementation of the present invention (by way of example only), the binary input end bit internal = consider the system ": heart symbols. These symbols can represent complex quantities : The direction of the horse is bluffed. It is assumed that the binary and binary digits that provide the length and the bit are rounded into the encoder in the beginning state, in order to require two. Yuan ^ Shi = The beginning of the encoder and decoder will start and in the same state. Far isomorphism is unknown to the demamarizer. Similarly, these consistent = Department =

: '1234X54505. Ptd page 18 V. Description of the invention (15) It is obtained by starting in a certain state, moving through interlacing, and ending in the same state as the starting state. Figure 8 shows an example of an interleaved section of an m = 2 interleaved encoder, which is provided for illustration. The four squares that are right-angled to the right of Figure 8 in the configuration represent the four possible shift register states of the m = 2 interleaved encoder, which have the contents indicated in these boxes. The complete interlaced system includes M consecutive segments that are the same as the parent segment shown in Figure 8. For a trailing bit interlace encoder, the interlace will wrap around and the final status bar will become the same as the first bar. The indicated arrows (for example, I / Code 1) indicate the current state and input signal (I) of the encoder (originated from the state of the arrow). The current output symbol is code (1), and the next The state will be 1 in the direction of the arrow. Note that the arrows shown in Figure 8 are clearly labeled, but the invention is not intended to be so limited. The code labels shown are for illustration purposes only and are not intended to specify the special mapping function used. -As described in Figure 8, the parent weaving sector description 'All the interleaving steps in the parent weaving code are the same, and the same code is repeated over and over again. As a result, 'the codeword path can be circularly interleaved as seen in FIG. Similarly, FIG. 9 is an exemplary diagram of circular interleaving with M equal to 8. Each square displayed represents a status field (for example, one of the right / left niches shown in Figure 8), and each arrow displayed represents a set of possible state transitions And relative input / output relationships. As stated previously, according to the present invention, all the interleaving steps shown are the same. As a result, any output sequence cyclic shift of the symbol is also a valid output sequence. Similarly, in a circle

C: \ 1234X54505. Ptd The interlaced path on page 19 'The actual positions of these start and stop are unknown. The origin and stop states are the same, but the start / stop status is used by the weaving center The decoder will be 4¾ • 隹 ^ \. 丨 ___, a collects M continually received symbols, and assumes interleaving three. T stop position. All cyclic shifts of a unitary path are also valid paths. As a result, the correct path (but not the start / stop position) is enough to decode (assuming the noise level is not too high). Obviously, although this trailing bit 7L encoder rule system does not satisfy feature 2 (above), all symbolic cyclic shifts of the codeword are valid codewords. However, the use of such an interlaced 'structure allows the use of soft-decision decoding techniques and more efficient interlacing of the structure. An overview of known techniques used to decode trailing bit interleaving codes is provided in " An Efficient by R. Cox and C-E. Sundberg

Adaptive Circular Vitcrbi Algorithm for Decoding Generalized Tailbiting Convolutional Codes ", IEEE

Transactions on Vehicular Technology, Volume 43, Number 11994, and 1? (: 0-) ((^ 81 U.S. Patent No. 5,355,376. Similarly, 'assuming the correct path is decoded (most often)), enter Μ A circular shifted version of the bit frame can be obtained. In order to force the above-mentioned inner codeword, so characteristic 2 should be satisfied. The external synchronization code of length M bits will be referenced, which constitutes this M bit frame. As shown below As stated, this external synchronization code satisfies characteristic 2. As a result, by treating these internal and external codes as a single code, the resulting single code will satisfy characteristic 2. Once the internal code has been decoded, the shifted version of the external code Can be obtained. However, only the shift of this decoded word will produce a valid outer codeword. As a result, the inner decoded word

C: U234 \ 54505.ptd Page 20 5. Description of the Invention (17) will shift until a valid codeword is obtained. These required shift numbers define the frame timing and the message relative to the LC I. If a valid codeword does not appear after the M shift is performed, it can be concluded that an internal decoding error has occurred, so that the present invention can thus provide a form of error removal. The following description shows that this type of synchronization code (which satisfies characteristic 2) actually exists, and the small value series of M is the codeword in the outer code. As such, the interleaving code will then define many different specific embodiments. An example series of synchronization codes (and their main ones) is currently described in accordance with the present invention so that each code can satisfy characteristic 2. For the purpose of description, M is set equal to 5 in this example, but the following reasons apply to any M value. Regarding feature 2, the limitation placed on the codeword is that any (important) cyclic shift must produce a distinct non-codeword. Similarly, the "cycle" of a word defines the number of cyclic shifts required to return to the word. In this specific embodiment, the period is less than or equal to M. " ρ -period " is defined as the period " ρ "-" ρ " block of period " will be obtained when the word "P" is shifted. The limit placed on each codeword has a period M, and the M-1 shifts are not codewords. From the above, the following rule system shown in Fig. 10 can be used by the encoder to generate all words satisfying characteristic 2. Please refer to FIG. 10, in step 301, for all 2M words of length M, the encoder calculates the period of the words. At step 302, the encoder will then exclude all words with periods below M. At step 303, the encoder excludes all words in the M period except one that can represent the period (for example, if the word is treated as a binary value, it is the smallest). In step 304, the encoder assumes that the remaining words can satisfy characteristic 2, and

C: \ 1234 \ 54505.ptd page 21 5. Description of the invention (18) The code to be used. The above rule system is shown in FIG. 11. As shown, > 丨 is equal to 5. The right arrow (->) indicates (for example, right) that a cyclic shift has occurred. All 25 = 3 2 words are used for explanation, and the 6 words are kept in the synchronization code of the result (rightmost column). As a result, in this example, the synchronous math to be used includes six word ma 1, 3, 5, 7, 11 1, 15 (decimal), and thus L = 6. FIG. 12 is a flowchart illustrating a method for decoding the synchronization code described in FIG. 11 according to the present invention. At step 401, the decoder collects M consecutive bits (obtained from internal decoding). At step 402, the decoder shifts the received frame by the maximum number of times M until it is as small as possible (for example, it can be considered as a binary value). At step 403, the decoder decides whether the generated word is a codeword. If it is a codeword, in step 404, the decoder will output the relative information of the codeword, together with the number of shifts required to obtain the codeword. Otherwise, if it is not a codeword, it can assume that an internal decoding error has occurred. In that case, at step 405, the decoder can output an internal decoding error message. Fig. 13 shows a list of the above-mentioned synchronization code search rule system, and Fig. 14 shows some major synchronization codes with small M values (i.e., the indication amount rather than the sequence). In the DS-CDMA system, these M code symbols include Q values of so-called length N short codes. These short codes are often orthogonal to each other or have good cross-correlation characteristics. Consider a low-rate time-invariant interleaving code, where the symbols on the interleaving branch are taken from the vectors of the above-mentioned Q vector group (or the symbols as referred to herein). For example, U.S. Patent No. 5, 193, 0 94 discloses such a set of vectors.

C: \ 1234X54505.ptd Page 22 V. Description of the Invention (19) ^ 15A # σ15B is a block diagram of the interleaving encoders 10 and 20, and the following two issues: In this f, such an interleaving encoder is a length-m shift register (12, 22) with the following input: f: " 4, 24), which performs mapping from the binary unit: vector (for example, cl, c ?, _χΠ6, said Cunyi (12, 22) and output, ^ "· ·. C -N) 's current input signal {的 映 " 3 Λ ^ " 1 〇' 2〇 ^ # ϋ C Λ 疋d. As a result, the temple shift is crying temporarily. The mother of 9 X and Nengshan ° 22 can adopt 8 different states. The output vector / symbol (for example, ci does not constitute a right-angle interleaved encoder 1Q (m5A) Right-angle vector groups, and c-supergroups are right-angle or opposite vector groups of the interleaved encoder 20 (Fig. 15B). Angle, sample, if the mapping from the state of the register and the turn-in signal produces ί r: ί For example, if m * 'and Γ; a set of right-angle vectors is obtained, and the right-angle interleaved code is U: U. The status of the register I-i register is a right-angle vector, and f will form two and can be used as output. Vector, unless the sum of the modulo 2 of the input bit and the state content of the mth register is equal to []. In this case, cough: out, the second is represented by the bit inverted by the inverter 26. With For example, once 0/1, A # ϋtypically maps' 彳 to see that the output of a state is opposite to i-rDM. Do n’t decide to enter 0 and 1 ° in such rounds as well. 'For the inherent use of' It, Such codes are suitable for use as symbols due to the interlaced spreading effect (very low bit rate), good correlation characteristics, and the inherent error correction ability of the structure. According to the new encoding (decoding) method of the present invention, the new method 22: The timing indication of the cell search frame using the encoding method of the present invention, such as the 'AR I β proposal using the broadband c DMA cell search method

V. Description of the invention (20) This article. Similarly, the relevant acquisition channel transmitted in the downlink is described in the targeted AR IB Broadband cD \ i proposal, which facilitates the three-step acquisition procedure included in the mobile station. However, since the relevant acquired channels do not include any information about the timing of the frame, the final steps of the proposed AR IB procedure are quite complex and / or time consuming. As described below, the present invention provides at least two functions that can be used to provide, for example, f τ I in the proposed AR-B wideband CDM A method. Specifically, FIG. 16 depicts the cell search method performed by the mobile station. The diagram is as described in the ARIB Broadband CDMA Proposal. On each time slot, the primary synchronization code (PSC) and secondary synchronization code (SSC) are transmitted in parallel with known modulation without the need to scramble the long code. The performance time of psc / ssc is one of the 16 k symbol actual channels per second or one of 256 chips. There are 乂% effective SSCs in the system, which provides 1 0¾ (NSS (:) information bits used by LCI. The characteristics of Psc and ssc are described in the table shown in Figure 7. As shown in Figure 7 In the description, no FTI is provided to the mobile station, and FTI makes the cell search take longer. Figure 18 shows a lean table provided by PSC / SSC for cell search according to the present invention. Although this The information can be provided in many ways, two specific examples are described below, and can be used in the currently proposed cell search method. Specifically, according to a specific implementation of the present invention (as described in FIG. 19) ^ as In the proposed AR IB method 'The SSC is the same in each of the frames', and there are valid SSCs in the system, which provide 10g2 (Nssc) information bits for LCI. The SSCs of the entire frame also have a length of 16

The five 'invention illustrates that the water QD of (21) may be modulated by a valid (eg, binary) sequence. This method provides additional log ^ U information bits used by LCI and LCI. The resulting modulation sequence of length 16 has good auto-interrelation characteristics. If the value is greater than 1, the following characteristics also need to be full: (1) good cross-correlation; and (2) cyclic shift without any effective modulation sequence can cause another effective modulation sequence (and any of them Cyclic shift). If the obtained modulation sequence satisfies these characteristics, the FTI will know that any valid modulation sequence has been detected in the receiver of the mobile station. The methodical detection of the received signal is to obtain a channel phase reference by using PSCs as reference symbols. As such, FTI is inherent. As a result, all 10 g2 (Nssc) + 10¾ () information bits of the information can be used for LC I. According to a second embodiment of the present invention (as described in FIG. 20), there are 16 SSCs sequences repeated in each frame. In general, Nsse sEQ with such SSC sequences can be used in the system, which can generate 10 g2 (NSSG_SEQ) information bits for L C I. In this case, if each S S C sequence is unique, it would be advantageous ^ and the individual SSCs have good automatic and interactive correlation characteristics. However, it assumes that the value ^ SSC_SEQ = 1 can actually be satisfied. In the search for an effective SSC sequence, the FTI will be substantially generated, and the SSC sequence can also be directly modulated by the method described in the first specific embodiment above, which will generate 1 og2 used by LC I (N negotiation) Message bits. In this case, the LCI can adopt 6 5, 5 3 6 different values (more than actual), which can provide a good L C I 彳 measurement efficiency. '' Figure 21 depicts a two-cell search rule system that can be used to implement the present invention

C: \ 1234 \ 54505.ptd Page 25

The table shown in the figure is that the present invention has these columns (steps) in the first stage (step 1 gap (ST) ° in the second stage and second stage accumulation related to SSC. Another-aspect, because each Only when the time slots are related to each other, this correlation can provide the ARIB wide description of this issue at each symbol in the message frame. On the kissed segment, both the correlation (CORR) and the correlation are SSC ° These associated consecutive symbols. Here (method) form. Similarly, a comparison of the two-cell search method illustrated in Figure 2i is proposed for a band CDMA cell search. Figure 21 includes the cell search phase. For example, the combined filter (MF) is used to generate the phase reference provided by the PSC. When in the second time, the association can be performed only once in each time slot. When in the third stage, Medium and long codes (LC) must be accumulated incoherently. However, the number is completed. Since the long code is used, the correlation is performed by concatenating the long code with the known short code of BCCH, and B C C Η is always transmitted on the downlink. If the long code can be correctly indicated by the LC, only one interrelated step needs to be used in the two specific embodiments described above. However, with the currently proposed AR [B-cell search method], in addition to the above steps, search is still needed in order to find the frame timing (FT). In order to describe the receiver operation required in the method shown in FIG. 21, the following selections can be made: Nssc = 2 56 long code grouped as 6 x 1 6: N_ = 1: ^ SSCSEQ = 1; and assume ( For simplicity, the consistent accumulation of 16 interrelated (each with 256 chips) is sufficient for proper detection. Similarly, in implementing the currently proposed AR I B cell search method, the following correlation matrix will be formed:

C: \. 1234 \ 54505. Ptd Page 26 V. Description of the invention (23) c〇y〇CiY〇c〇Yi ** · c〇y15 ci Ϋ… hy15 y〇 where 5 means 16 different SSCs s,% indicates 16 consecutive SSCs received, and dot product indicates the correlation performed. With 16 correlators in the receiver of the mobile station, the 16 correlators need to operate in 16 time slots, in order to form 25.6 correlations of Zt. The Zi element can also be multiplied by the relative PSC to combine them in order to remove phase shifts caused by radio channel and frequency synchronization errors. Similarly, this multiplication system is assumed to have been performed in the above-mentioned matrix (1), but it can also be used in other descriptions. The columns of Z, are then summed. One of these sums will have a larger size than the rest, indicating the size of the SSC. According to the first specific embodiment (Method 1 described above), the matrix (1) is also formed. However, to implement method 1, the matrix (1) is also multiplied by the following moment i car.

m0

m2

(2) Where these columns include modulation sequences (here, for simplicity, real numbers are assumed

C: \ 1234X54505. Ptd page 27 5. Description of the invention (24) value) All cyclic shifts. This multiplication Zt results in a 1 6 X 1 6 matrix, where one of these elements has a larger size than the other. The column index of this element will generate L C I, and the plutonium index will generate frame timing (F T I). According to the second specific embodiment of the present invention (the above method 2) for replacing the matrix (1), the following matrix will be formed: 4 5… C15y15 'c, y〇 c2y, ... coy15 (3)

Z, c15y〇 coy, ... cuy15, where h is the S S C s of the S S C sequence. This matrix (3) is then multiplied by the following matrix: 〆 (0 1 {1 I (15 'm0 m0 ··· m〇

These columns indicate all 16 possible modulation sequences (again assuming real values to simplify). The matrix multiplication 4 will produce a 1 6 X 1 6 matrix, where one of these elements will have a larger size than the other. The column index of this element will generate FTI, and the block index will generate LC I. The above-mentioned operation method of the present invention can be extended to include more general conditions. For example, if more modulation sequences are needed, the matrix% (M2) can expand the new

C: · 123 <. \ 54505, ptd page 28 5. Column (25) of the description of the invention, which includes the displacements of all allowed in sequences. If more S S C sequences are intended to be used to implement the second method described above, the matrix Z can be expanded by adding displacement correlation columns with all allowed S S C sequences. If each group has more long codes, the matrix Z 1 of the first method described above can be expanded by increasing the correlation of more rows. Similarly, with the use of a limited set of correlators, these correlations can be performed in subsequent frames, but still accumulate consistently. This observation is effective for the above-mentioned two-cell search method of the present invention. The following description compares the two-cell search method of the present invention with the proposed AR IB wideband CDMA cell search method. To perform this comparison 'assume that the system parameters shown in the table of Figure 22 apply to each of the following cases. Fig. 2 A-D are tables describing the advantages of the two-cell search method of the present invention on the proposed AR R B wideband c DM A cell search method. For example, the table in Fig. 2 A shows the number of 2 5 6 wafers required to be interconnected 'and the time required to reach these three. The downlink synchronization of the cell search method' for this case 'where and No long code alignment. The table in Fig. 23B shows the same §R including the case of four long code groups each of 32 yards. The table in FIG. 2 3 C shows 16 long code groups, and each includes the same information of 16 codes. The table in FIG. 2 D shows 16 long code groups, and each Each includes 4 yards of the same information. Similarly, the first step (the matching filtering or MF stage) is the same as all three methods. Result 'This step can be obtained from Fig. 2 a-d for simplicity. For some associations, maximum and average values are provided. The reason is that when the blind search brother is executed in L C or F T ’when a good enough match is obtained, the

C: \ 1234 \ 54505.ptd Page 29 V. Description of the invention (26) The correlation process can be finished before all possible combinations are searched. When performing a blind search (for example, between N different codes), the average M 1 2 code must be tested. However, for the worst case, all N codes must be stabbed. Similarly, the matrix multiplication Z: Μ | is assumed to be executed instantaneously, and their complexity is not considered in the table above. In short, as described in Figures 2 A to D, the two-cell search method is described above and is performed in accordance with the present invention. It helps to reduce the number of The mobile station includes a simple cell search process. Similarly, as shown in the tables in FIGS. 23A-D, the delay and complexity of the cell search method of both of the present invention are lower than the proposed AR B cell search method. In particular, the third stage (step 3) of the mobile station cell search process with the two methods of the present invention is up to 16 times faster and lower than the complexity of the proposed ARIB method. Although the preferred embodiments of the method and device of the present invention have been described in conjunction with the drawings and described in detail above, it can be understood that the present invention is not limited to the disclosed specific embodiments, which can be reconfigured differently, Modifications, and replacements without departing from the spirit of the invention as published and defined in the scope of the following patent applications.

C: '1234X54505.ptd p.30

Claims (1)

6. Scope of patent application 1. A method for conveniently finding cells in a cellular communication system, including the following steps: a base station that generates an identification code group for transmission, the identification code group includes a plurality of Codewords, and the codewords include a plurality of symbols from a set of short codes, and each codeword of the multiple digital words is defined so that the cyclic shift of the symbols of each codeword does not produce a valid The codeword; and the base station transmits the generated identification code. 2. The method according to item 1 of the scope of patent application, wherein the multiple digital characters include a plurality of Q-ar y codewords, and the short code of the group includes a short code of Q. 3. The method of claim 2 in the scope of patent application, wherein the majority of Q-ary codewords includes a majority of long MQ-ary codewords. 4. The method according to item 1 of the scope of patent application, wherein the identification code is formed by concatenating an inner code and an outer code. _ 5. The method according to item 4 of the patent application, wherein the inner code includes an interleaving code of a trailing bit. -6. If the method according to item 4 of the scope of patent application is applied, wherein the outer code includes a binary stone horse. 7. The method of claim 5 in which the trailing bit interleaving code includes an orthogonal interleaving code. 8. The method of claim 5 in which the tail bit interleaving code comprises a super-orthogonal interleaving code. 9. A method for a mobile station to decode an identification code transmitted from a base station in a CDM A cellular communication system, comprising the steps of: receiving a plurality of consecutive symbols including the identification code; C: '123 <. \ 54505. Ptd page 31 6. The scope of patent application determines whether the plurality of consecutive symbols received includes a valid code word; and if the plurality of consecutive symbols received does not include a valid code Word, cyclically shift the received plurality of consecutive symbols by a predetermined amount, and return to the determination step; if the received plurality of consecutive symbols include a valid codeword, output a majority of cyclic shifts, To obtain the valid codeword and a message having the valid codeword. 10. The method according to item 9 of the scope of patent application, wherein the number of cyclic shifts used to obtain the effective codeword indicates the frame timing of the effective codeword. 1 1. The method of claim 9 in the scope of patent application, wherein the plurality of consecutive symbols include a predetermined number of consecutive symbols. 1 2. The method of claim 9 in the scope of patent application, wherein the predetermined amount includes a sign. 1 3. A method for a mobile station to decode an identification code transmitted from a base station in a CD M A cellular communication system, which includes the following steps: Collecting k by M consecutive symbols, the M Consecutive symbols include the identification code; Calculate a possible combination of the collected k multiplied by M consecutive symbols; For each L codeword and each M cyclic link shift of the collected consecutive symbols, calculate Correlation between such k multiplied by consecutive symbols collected and all obtained M multiplied by L consecutive symbols: and codewords and chain shifts that are stored in the calculation step to produce a higher correlation value number. 1 4. The method according to item 13 of the scope of patent application, wherein the following links are generated C: \ 123 (\ 54505. Ptd page 32 6. The number of shifts in the scope of patent application indicates the frame sequence of the identification code. 1 5. The method of item 13 in the scope of patent application, including outputting the stored information Steps of code word message. 16. A method for encoding an identification code transmitted from a base station in a CD Μ Λ cell communication system, including the following steps: Calculate a period, which Is to encode each / word of length M as one cycle of the identification code; excluding each of these / words with a period less than M; for each M cycle of the remaining words of these 2M words, determine a Representative words: and storing each of the representative words. 1 7 · As in the method of claim 16 of the scope of patent application, each of the stored representative words includes a plurality of code words, and the multiple digits A sequential shift of any codeword in a word does not produce a valid codeword. C: \ 1234 \ 54505.ptd Page 33