HK1134180B - Acquisition in frequency division multiple access systems - Google Patents

Description

Acquisition in frequency division multiple access systems

Cross Reference to Related Applications

The present application claims priority to a provisional application, serial No. 60/839,954, filed on 23.8.2006 under the name "ACQUISITION METHOD AND APPARATUS FOR FDMA systems" (a METHOD AND APPARATUS FOR ACQUISITION INFDMA SYSTEMS). The entire contents of this provisional application are incorporated herein by reference.

Technical Field

The following description relates generally to wireless communications, and more particularly to cell acquisition and acquisition of sequences of cell information using synchronization channels and broadcast channels.

Background

Wireless communication systems have been widely deployed to provide various types of communication content such as voice, video, data, and so on. These systems may be multiple-access systems capable of supporting communication for multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems. However, regardless of the specific characteristics of various existing wireless communication systems, in each system, a terminal or wireless device must perform cell acquisition or cell search upon power-on before it can function properly. Cell acquisition is the process by which a terminal acquires synchronization with network time and frequency, cell identification, and other identifications of system information critical to operation (e.g., system bandwidth, antenna configuration of the cell transmitter, etc.).

In wireless systems like third generation long term evolution (3G LTE) or evolved universal terrestrial radio access (E-UTRA), the beneficial features of increasing communication performance, such as the presence of cyclic prefixes to migrate inter-symbol interference in orthogonal frequency division multiplexing, and the versatility of downlink system bandwidth (e.g., 3G LTE systems can support multiple bandwidths: 1.25MHz, 1.6MHz, 2.5MHz, 5MHz, 10MHz, 15MHz, and 20MHz) create unique complexities during initial cell acquisition. In addition to time synchronization (i.e., detection of symbol boundaries, 0.5ms slot boundaries, 1ms subframe boundaries, 5ms half radio frame boundaries, and 10ms full radio boundaries, 40ms broadcast channel transmission time intervals) and frequency synchronization (involving acquisition of downlink frequencies so that they can be used as frequency references for uplink transmissions), there are other complexities, such as determining the bandwidth for cell acquisition, the physical channels used during cell acquisition, and, more importantly, the information carried by these channels during cell acquisition. While much work has been done to address each of these problems, there is no consensus in the industry regarding cell acquisition protocols that are fast, reliable, and consume a small amount of resources. Therefore, there is a need for a cell acquisition protocol having the above-mentioned features.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of the invention. Its purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

According to one aspect, an apparatus that operates in a wireless communication environment is presented, the apparatus comprising: a processor configured to receive a code sequence in a primary synchronization channel, the code sequence conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of a broadcast channel bandwidth and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; a memory coupled to the processor for storing data.

According to one aspect, an apparatus that operates in a wireless communication environment is presented, the apparatus comprising: a processor configured to transmit a code sequence in a primary synchronization channel, the code sequence conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of a broadcast channel bandwidth and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; a memory coupled to the processor for storing data.

According to one aspect, an apparatus for operating in a wireless communication environment using orthogonal frequency division multiple access is presented, the apparatus comprising: a plurality of detection components that simultaneously acquire a plurality of cell information within a plurality of subcarrier time intervals; a processor for processing the plurality of cell information; a memory coupled to the processor for storing data.

According to one aspect, an apparatus that operates in a wireless communication environment is presented, the apparatus comprising: means for receiving a code sequence of primary synchronization channel symbols, the code sequence conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of broadcast channel bandwidth and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; means for receiving one or more code sequences of secondary synchronization channel symbols conveying at least one of a radio frame boundary, a portion or all of a cell identification code, and an indication of a broadcast channel bandwidth.

According to one aspect, a machine-readable medium is provided that includes instructions, which when executed by a machine, cause the machine to perform operations comprising: receiving a code sequence of primary synchronization channel symbols, the code sequence conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of broadcast channel bandwidth and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; receiving one or more code sequences of secondary synchronization channel symbols, the one or more code sequences conveying at least one of a radio frame boundary, a portion or all of a cell identification code, and an indication of a broadcast channel bandwidth; a code sequence of broadcast channel symbols is received, the code sequence conveying at least one of cyclic prefix timing and wireless system bandwidth.

According to one aspect, a machine-readable medium is provided that includes instructions, which when executed by a machine, cause the machine to perform operations comprising: transmitting a code sequence of primary synchronization channel symbols on a 1.25MHz frequency, the code sequence conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of broadcast channel bandwidth and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; transmitting one or more code sequences of secondary synchronization channel symbols over a 1.25MHz frequency, the one or more code sequences conveying at least one of a radio frame boundary, a portion or all of a cell identification code, and an indication of a broadcast channel bandwidth.

According to one aspect, a method for use in a wireless communication system is presented, the method comprising: receiving a code sequence in a primary synchronization channel (P-SCH) that conveys at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of a broadcast channel bandwidth and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; receiving one or more code sequences in a secondary synchronization channel (S-SCH), the one or more code sequences conveying at least one of a radio frame boundary, a portion or all of a cell identification code, and a broadcast channel bandwidth indication; receiving a code sequence in a Broadcast Channel (BCH), the code sequence conveying at least one of cyclic prefix timing and wireless system bandwidth; and processing P-SCH, S-SCH and BCH code sequences, and extracting cell information transmitted by the code sequences.

According to one aspect, a method for use in a wireless communication system is presented, the method comprising: transmitting a code sequence of primary synchronization channel symbols conveying at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of broadcast channel bandwidth, and facilitating orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; transmitting one or more code sequences of secondary synchronization channel symbols, the one or more code sequences conveying at least one of a radio frame boundary, a portion or all of a cell identification code, and an indication of a broadcast channel bandwidth; a code sequence in a broadcast channel is transmitted that conveys at least one of cyclic prefix timing and wireless system bandwidth.

To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and are indicative of but a few of the various ways in which the principles of the embodiments may be employed. Other advantages and novel features of the invention may become apparent from the following detailed description of the invention when considered in conjunction with the drawings and the disclosed embodiments are intended to include all such aspects and their equivalents.

Drawings

Fig. 1 shows a system in which a user equipment acquires cell information from a base station.

Fig. 2 is a block diagram of a MIMO transmitter and receiver.

Fig. 3 is a block diagram of a MU-MIMO structure.

FIG. 4 shows the transmission structure of P-SCH codes, S-SCH codes, and BCH codes.

Fig. 5A and 5B illustrate synchronization and broadcast channel bandwidth utilization.

Fig. 6 shows information conveyed by the synchronization channel and the broadcast channel.

Fig. 7A, 7B, and 7C illustrate cell acquisition sequences.

Fig. 8A and 8B illustrate relaying of cell information.

Fig. 9A, 9B, and 9C illustrate a system in which a terminal simultaneously acquires cells operating with frequency reuse.

Fig. 10 is a block diagram of a structure of a system in which a terminal simultaneously acquires a plurality of cells operating with frequency reuse.

Fig. 11 is a flow chart of a method of performing cell acquisition.

Fig. 12 is a flow chart of a method of relaying cell synchronization information.

Fig. 13A and 13B are flow diagrams of methods of transmitting and receiving cell information using frequency reuse, respectively.

Fig. 14 depicts an example system that supports receiving code sequences for primary and secondary synchronization channel symbols in accordance with one or more aspects.

Detailed Description

Various embodiments are described below with reference to the drawings, wherein like reference numerals represent like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, the use of "exemplary" once is intended to represent the concept in a particular situation.

Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless stated otherwise, or clear from context, "X employs A or B" means any of the natural inclusive permutations. That is, if X uses A, X uses B, or X uses both A and B, "X uses A or B" is satisfied under any of the above examples. In addition, the use of "a" and "an" in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

As used in this application, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to: a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Moreover, various embodiments of a mobile device are described herein. A mobile device can also be called a system, subscriber unit, subscriber station, mobile, remote station, remote terminal, access terminal, user terminal, wireless communication device, user agent, user device, or User Equipment (UE). The mobile device may be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having wireless connection capability, a computing device, or other processing device connected to a wireless modem. Various embodiments are described herein in connection with a base station. A base station can be utilized for communicating with mobile device(s) and can also be referred to as an access point, node B, or some other terminology.

The term "processor" as used herein may refer to a standard architecture or a quantum computer. Standard architectures include, but are not limited to, single-core processors with software multithreading capability, multi-core processors with software multithreading capability, multi-core processors with hardware multithreading, parallel platforms, and parallel platforms with distributed shared memory. Further, the processor may represent an Application Specific Integrated Circuit (ASIC). Quantum computer architectures may be based on qubits contained in quantum dots employing gated or self-assembled, nuclear magnetic resonance platforms, superconducting josephson junctions, and the like. Processors may utilize nanoscale architectures such as, but not limited to, molecular or quantum dot based transistors, switches, and gates to optimize space usage or enhance performance of user devices.

In this specification, the term "memory" means a data storage device, an algorithm storage device, and other information storage devices such as, but not limited to, an image storage device, a digital music and video storage device, a chart, and a database. It will be appreciated that the memory components described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of example, and not limitation, nonvolatile memory can include Read Only Memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM), which acts as external cache memory. By way of example and not limitation, RAM may take many forms, such as Synchronous RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), and direct memory bus RAM (DRRAM). Moreover, the disclosed memory components of systems and/or methods herein are intended to comprise, without being limited to, these and any other suitable types of memory.

Moreover, various aspects and features herein may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term "article of manufacture" as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., Compact Disk (CD), Digital Versatile Disk (DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). Additionally, the various aggregated storage media described herein represent one or more devices and/or other computer-readable media for storing information. The term "computer-readable medium" can include, without being limited to, wireless channels and various other media capable of storing, containing, and/or carrying instruction(s) and/or data.

Systems and methods for performing cell acquisition based on code sequences transmitted on a primary synchronization channel (P-SCH), a secondary synchronization channel (S-SCH), and a Broadcast Channel (BCH) are described below. Details of the information conveyed by the P-SCH, S-SCH, BCH, and the sequence used to convey the information are given. Additionally, relaying of cell acquisition information is described, as well as acquisition of multiple cells when the wireless system operates with frequency reuse.

Fig. 1 shows a system 100 in which a user equipment 120 acquires cell information from a base station 140 through code sequences transmitted over a downlink 160 on a primary synchronization channel (P-SCH)162, a secondary synchronization channel (S-SCH)164, and a Broadcast Channel (BCH) 166. User device 120 can include detection component 122, processor 124, and memory 126. The base station 140 may include a sequencer component 142, a processor 144, and a memory 146. The sequence generator component 142 generates code sequences that include cell search information such as system bandwidth, antenna structure at the base station 140 (see below), cell Identification (ID), etc. The length of the sequence is N symbols, the number of bits of the symbols depending on the employed modulation constellation (e.g. BPSK, QPSK, 16-QAM, 64-QAM). The sequence may be a pseudo-random code [ e.g., Gold sequence, Walsh-Hadamard sequence, M-sequence (maximal length sequence), and pseudo-noise sequence ] or a general Chirp-like sequence (e.g., Zadoff-Chu). In Orthogonal Frequency Division Multiple Access (OFDMA), an information stream is mapped to a set of M frequency subcarriers, each of which has a frequency width Δ v/M, where Δ v is the system bandwidth (e.g., 1.25MHz, 2.5MHz, 5MHz, 10MHz, 15MHz, 20 MHz). The subcarriers are typically orthogonal tones. A serial-to-parallel (S/P) component 150 parses the N-symbol long sequence into a frame of N symbols and maps these N symbols onto M subcarriers. (Note that the S/P component 150 may also be located in the sequencer component 144 instead of the separate component shown in FIG. 1). Inverse discrete fast fourier transform (IFFT) component 152 generates a time representation of the parallel frames. (it should be understood that component 152 may also be an integral part of processor 142.) once the IFFT is applied, a Cyclic Prefix (CP) is added to the beginning of the time domain symbol in each transmitted radio subframe. The CP is introduced as a guard interval to prevent inter-symbol interference (ISI) and inter-carrier interference (ICI). A parallel-to-serial converter (not shown) generates a time-domain symbol stream for each sequence generated by sequence generator component 142, which streams are transmitted in downlink 160. P-SCH 162, S-SCH 164, and BCH 166 code sequences are generated and transmitted.

Base station 140 may also include an Artificial Intelligence (AI) component 148. The term "intelligence" refers to the ability to reason or draw conclusions (e.g., infer) about the current or future state of a system based on existing information about the system. Artificial intelligence can be employed to identify a particular context or action, or to generate a probability distribution over particular states of a system, without human intervention. Artificial intelligence relies on applying advanced mathematical algorithms to a set of system-available variables (information), such as decision trees, neural networks, regression analysis, cluster analysis, genetic algorithms, and reinforcement learning. In particular, the AI component 148 can employ one of a number of methods to learn from data and then infer based upon a constructed model, such as a Hidden Markov Model (HMM) and related prototypical dependency models, more general probabilistic graphical models, such as Bayesian networks, e.g., by using Bayesian model scores (score) or approximations, linear classifiers, such as Support Vector Machines (SVM), non-linear classifiers, such as methods referred to as "neural networks," fuzzy logic methods, and other methods of data fusion, etc., in accordance with various automated aspects described below.

In the user equipment 120, a detection component 122, which can include a correlator 128 and a fast Fourier component, detects the P-SCH 162 code, S-SCH 164 code, and BCH 166 code and performs cell acquisition, which enables the user equipment 120 to communicate with the base station 140. The detection of the P-SCH, S-SCH, and BCH codes and the information conveyed thereby are presented in detail below in accordance with various aspects of the subject application.

Fig. 2 is a block diagram of an embodiment of a transmitter system 210 (e.g., base station 140) and a receiver system 250 (e.g., user equipment 120) in a multiple-input multiple-output (MIMO) system that can provide sector communication in a wireless communication environment in accordance with one or more aspects set forth herein. At the transmitter system 210, traffic data for a number of data streams can be provided from a data source 212 to Transmit (TX) data processor 214. In one embodiment, each data stream is transmitted over a respective transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. The coded data for each data stream is multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., symbol mapped) based on a particular modulation scheme [ e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), multi-phase-shift keying (M-PSK), or M-ary quadrature amplitude modulation (M-QAM) ] selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., OFDM). TX MIMO processor 220 then passes N_TOne modulation symbol stream is provided to N_TAnd Transmitters (TMTR)222a through 222 t. In some embodiments, TX MIMO processor 220 applies beamforming weights (or precoding) to the symbols of the data streams and to the antenna from which the symbol is being transmitted. Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Then from transmitter 222_ATo 222_TN of (A)_TFrom corresponding N of the modulated signals_TAntenna 224₁To 224_TAnd (4) transmitting. At the receiver system 250, the transmitted modulated signal is composed of N_RAn antenna 252₁To 252_RUpon reception, the received signal from each antenna 252 is provided to a respective receiver (RCVR)254_ATo 254_R. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding "received" symbol stream.

RX data processor 260 then proceeds from N based on the particular receiver processing technique_RA receiver 254 receives and processes N_RA stream of received symbols to provide N_TA stream of "detected" symbols. RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 260 is complementary to that performed by TX mimo processor 220 and TX data processor 214 at transmitter system 210. A processor 270 periodically determines which pre-coding matrix to use (described below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion. The reverse link message may includeVarious types of information regarding the communication link, the received data stream, or a combination of both. The reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, which is modulated by a modulator 280, and transmitted by a transmitter 254_ATo 254_RConditioned and transmitted back to the transmitter system 210.

At transmitter system 210, the modulated signals from receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by a RX data processor 242 to extract the reserve link message transmitted by receiver system 250. Processor 230 then determines which pre-coding matrix to use for determining the beamforming weights and processes the extracted message.

As shown in fig. 2 and in accordance with the foregoing description, a single-user MIMO mode of operation corresponds to the situation where a single receiver system 250 is in communication with transmitter system 210. In such a system, N_TA transmitter 224₁-224_T(also called TX antenna) and N_RA receiver 252₁-252_R(also referred to as RX antennas) constitute a matrix channel (e.g., a rayleigh channel or a gaussian channel) for wireless communication. SU-MIMO channel consisting of N_R×N_TIs described by a random complex matrix of. Rank of channel is equal to N_R×N_TThe algebraic rank of the channel. In space-time or space-frequency coding, the rank is equal to the number of data streams or layers transmitted over the channel. It should be appreciated that the rank is maximally equal to min N_T，N_R}. From N_TA transmission sum N_RThe MIMO channel formed by the receiving antennas can be decomposed into N_VA separate channel, which may be referred to as a spatial channel, where N_V≤min{N_T，N_R}。N_VEach of the individual channels corresponds to a dimension.

In one aspect, the symbols transmitted/received with OFDM at tone ω can be modeled using the following equation:

y(ω)＝H(ω)c(ω)+n(ω)。 (1)

here, y (ω) is the received data stream, N_RA vector of x 1, the vector of x 1,H(ω) is the matrix N_R×N_TChannel response at tone ω (e.g., time-varying channel response matrix)hFourier transform of (c) is N_TX 1, N (ω) is N_RA noise vector of x 1 (e.g., additive white gaussian noise). The precoding may be N_VConversion of x 1 layer vector to N_TX 1 precode the output vector. N is a radical of_VIs the actual number of data streams (layers) transmitted by the transmitter 210, N_VCan be scheduled by the transmitter (e.g., base station 140) itself based at least in part on the rank and channel conditions reported by the terminal. It should be understood that c (ω) is the result of at least one precoding (or beamforming) scheme and at least one multiplexing scheme applied by the transmitter. In addition, c (ω) is convolved with a power gain matrix that determines the allocation of transmitter 220 to transmit each data stream N_VThe amount of power of. The upper bound for the net power used in transmission is defined by the specified transmit power of the transmitter in wireless communications.

In system 200 (FIG. 2), when N is_T＝N_RWhen 1, the system reduces to a single-input single-output (SISO) system, which may provide sector communication in a wireless communication environment in accordance with one or more aspects set forth herein.

FIG. 3 shows an exemplary multi-user MIMO system 300 in which three UEs 120_P、120_UAnd 120_SCommunicating with the base station 140. The base station has N_TMultiple TX antennas, each UE having multiple RX antennas, i.e. UEs_PHaving N_PAn antenna 252₁-252_P，UE_UHaving N_UAn antenna 252₁-252_U，UE_SHaving N_SAn antenna 252₁-252_S. Communication between the terminal and the base station is via an uplink 315_P、315_UAnd 315_SAnd (5) realizing. Similarly, the downlink 310_P、310_UAnd 310_SAssisting base station 140 and terminal UE, respectively_P、UE_UAnd UE_STo communicate between them. Additionally, as described in fig. 2 and its corresponding description, communication between each terminal and the base station is implemented in substantially the same manner through substantially the same components. Because terminals may be located at substantially different locations within the cell serviced by base station 140, each terminal 120 may be located at a different location within the cell_P、120_UAnd 120_SWith its own matrix channelh _αAnd a response matrix H (α — P, U and S) and has its own rank. Inter-cell interference may exist due to multiple users existing in the cell served by the base station 140. Although 3 terminals are shown in fig. 3, it should be understood that a MU-MIMO system may include any number of terminals, which is indicated by the following indicator k.

In one aspect, for user k, the symbol transmitted/received with OFDM at tone ω can be modeled using the following equation:

y_k(ω)＝H _k(ω)c_k(ω)+H _k(ω)∑′c_m(ω)+n_k(ω)。 (2)

here, the symbols have the same meanings as in the formula (1). It should be appreciated that due to multi-user diversity, the interference of other users in the signal received by user k is modeled using the second term to the left of the equality sign of equation (2). The symbol (') represents the symbol vector c to be transmitted_kExcluded from the summation. The terms in the series represent the channel response received by user k (through which user k responds)H _k) Symbols transmitted by a transmitter (e.g., base station 140) to other users in the cell. The inter-cell interference at least partially determines the channel conditions, and it is therefore apparent that the channel state information at the transmitter (CSIT) determined in MU-MIMO operation may be inherently different from the CSIT in SU-MIMO operation described previously.

FIG. 4 shows exemplary diagrams 410, 420 and 430 of the transmission structures of P-SCH, S-SCH and BCH codes. As previously described, transmission is completed in a 10ms radio frame, which has a 1ms subframe (not shown) and a 0.5ms slot. Symbols are transmitted in these time slots. It should be understood that in 3G LTE, the number of symbols in each subframe depends on the length of the CP: for long CP (e.g., 16.67 μ s), each slot may accommodate 6 symbols, and for short CP (e.g., 4.69 μ s), 7 symbols. The code symbols may occupy one or more available symbols in the subframe. Further, the length of the transmitted sequence code may be N symbols for P-SCH, M symbols for S-SCH, and L symbols for BCH, where the integer N, M, L may be different or the same. Diagrams 410, 420 and 430 show an exemplary scenario of a stream of N symbols (N-M-L) with different "orders", where the order is given by the number of symbols sent in each frame. The order of the emission structure may affect the efficiency of the detection: higher order transmissions may provide faster detection, resulting in faster cell acquisition than lower order structures; however, since the base station (e.g., base station 140) continuously transmits acquisition codes such as P-SCH, S-SCH, and BCH codes, a high-order structure may be detrimental to the data rate after acquisition is complete. It should be appreciated that the acquisition codes are continuously transmitted because the terminals (e.g., user equipment 120) in the serving cell are asynchronously powered on or asynchronously enter the cell from a peripheral cell without an appropriate synchronization mechanism.

Drawing 410 shows a transmission structure of order 3 in which one symbol of a P-SCH code, one symbol of an S-SCH code, and one symbol of a BCH are transmitted in each frame. The P-SCH code symbol is transmitted first, delayed by a time τ with respect to the radio frame boundary; followed by a delay of tau_SPS-SCH code symbol of time of (a); tau is_BSAfter which the BCH code symbol is transmitted. The time between the BCH symbol and the radio frame boundary is τ'. Note that the times τ, τ_SP、τ_BSAnd τ' may be used as a parameter for design to facilitate detection of frame and subframe boundaries. In the transmit structure 410, the code length is commensurate with the number of radio frames (e.g., 3 × N symbols are transmitted in N radio frames). Diagram 420 shows a 2-stage structure where two symbols are transmitted in each frame, with the symbols periodically occupying the following frames. In this transmission structure, the transmitted symbols are not commensurate with the frame. Thus, the information may be redundantly transmitted to transmit specific cell information using a 3-channel code, as described below. 1 st order structure transmission corresponds to P-SCH. S-SCH and BCH. After cell acquisition, it may be slower in order 1 transmissions than higher order, which may utilize bandwidth more efficiently than a 3-order structure. It should be appreciated that in a terminal (e.g., user equipment 120) having a single detection component (e.g., detection component 122), cell acquisition can occur hierarchically, e.g., information carried in a P-SCH code is acquired first, followed by acquisition of information in an S-SCH code and information carried in a BCH. It should be understood that transmit architectures other than 410, 420, and 430 are possible and fall within the scope of the present application.

FIGS. 5A and 5B illustrate two bandwidth utilization schemes 510 and 520 for transmitting P-SCH, S-SCH and BCH code sequences for exemplary system bandwidths (1.25MHz, 5MHz, 10MHz and 20MHz), according to one aspect. Acquisition codes (e.g., codes to transmit cell operation information to wireless devices such as user equipment 120) may utilize a small portion of the system bandwidth due to (a) the fact that the system bandwidth is unknown prior to system acquisition, (b) the specific nature of the information transmitted, and (c) the possibility of transmitting this information with a shorter code (smaller N). Thus, the remaining bandwidth may be used for transmission of subscriber station data (e.g., user data, channel quality indicator channel, acknowledgement channel, load indicator channel, etc.). In one aspect, the synchronization channels (primary synchronization channel and secondary synchronization channel) and the broadcast channel may be transmitted at 1.25MHz regardless of the system bandwidth (scheme 510). For example, in 3G LTE, 83 subcarriers may be accommodated in such a frequency interval. In another aspect, the synchronization channel may be transmitted at 1.25MHz regardless of the system bandwidth, while the broadcast channel may be transmitted at 1.25MHz when the system bandwidth is 1.25MHz and may be transmitted at more than 5MHz when the bandwidth is wider (scheme 520).

Fig. 6 illustrates information conveyed by a synchronization channel and a broadcast channel, according to an aspect. As given in 610, the code sequence of the SCH may be used for (1) OFDM symbol boundary detection, (2) coarse frequency synchronization, (3) radio frame boundary detection, (4) Cyclic Prefix (CP) timing, (5) cell identification, and (6) BCH bandwidth indication. In particular, the primary synchronization channel may be used for coarse frequency synchronization and OFDM symbol, slot, and subframe time boundaries. With the appropriate transmit structure, the secondary synchronization channel can be used for 5ms half radio frame and 10ms radio frame boundary detection. As given in 620, the code sequences of the BCH can be used for (a) CP timing, (b) system bandwidth, and (c) other system information, e.g., base station antenna structure, peripheral cell information, etc. Timing information, as well as frequency synchronization, may be obtained by the detection component 122 and the correlator 128 in the processor 124. The repeated sequences transmitted on the downlink 160 are detected by the correlator 128 and timing metrics are calculated by the processor 124. Timing and frequency synchronization methods, such as the Moose method, the Van De Beenk method, and the Schmidl method, propose to use a specific code sequence of repeated portions of the transmitted code to estimate frame subframe boundaries, as well as frequency offset. It should be understood that other methods may be used for symbol boundary detection, CP duration and frequency synchronization. After timing and frequency synchronization, the code sequences carrying system information (e.g., cell identity, BCH and system bandwidth, antenna structure of the base station) can be demodulated by the FFT component 130 in the detection component 122, and then cell acquisition can be completed.

Transmitting the information listed in blocks 610 and 620 may be accomplished through a combination of P-SCH, S-SCH, and BCH code sequences. Fig. 7A, 7B, and 7C illustrate cell acquisition sequences in accordance with aspects of the present disclosure. In one of these aspects, acquisition sequence 725 (fig. 7A) acquires 730 OFDM symbol boundaries by (time or correlation) detecting a Primary Synchronization Code (PSC) sequence; the P-SCH is transmitted at 1.25MHz (FIG. 5A). It should be understood that all cells transmit the same PSC sequence; as described above, the sequences may be, but are not limited to, general Chirp-like sequences (e.g., Zadoff-Chu sequences), Walsh-Hadamard sequences, Gold code sequences, M-sequences, pseudo-noise sequences, and the like. Frequency synchronization is accomplished at 730. Then, in 735, the radio frame boundary and cell identification are detected by a Secondary Synchronization Code (SSC) sequence; the S-SCH is transmitted at 1.25MHz (FIG. 5A). In one aspect, to convey cell identification information, the sequence transmitted in the S-SCH is selected to indicate all possible 512 hypotheses (number of cell identifications) in 3G LTE. Note that each cell identification code may be transmitted using 9 bits. In 740, the CP duration, downlink system bandwidth, and other system information are acquired through demodulation of the broadcast channel, which is transmitted at 1.25MHz (fig. 5A). It should be appreciated that CP timing can be detected after a symbol boundary is detected. Further, CP timing is necessary for successful demodulation of OFDM data symbols in OFDM because the CP timing guard interval is added to the receiver (e.g., by processor 122) after the frequency domain modulation transform (IFFT) into a time domain symbol stream, and the CP is removed in the pre-FFT state during data detection.

In another aspect, acquisition sequence 750 acquires the OFDM symbol boundary and CP timing during decoding of the P-SCH sequence in 755. Two sequences transmitted at 1.25MHz (fig. 5B) may be used to accomplish such acquisition. To reduce inter-symbol interference, the sequences may be orthogonal, e.g., Walsh-Hadamard codes; however, other sequences are contemplated and fall within the scope of the present application. As in sequence 725 described previously, each cell transmits one of two PSC sequences. It should be appreciated that once the P-SCH is detected, demodulation of the data (rather than the training or pilot sequence) may be completed. Frequency synchronization may also be accomplished at 755. In 760, the S-SCH sequence transmitted at 1.25MHz (FIG. 5B) can describe 1024 hypotheses, which may include 512 cell identification codes. A BCH bandwidth indication is obtained, which may be 1.25MHz or 5 MHz. In 765, the BCH code sequence is demodulated, which carries other system information, such as the antenna structure of the station, the identities of neighboring cells, etc. It should be understood that the amount of information transmitted in the BCH may be proportional to the channel bandwidth. In addition, sequence 750 supports a variable transmission bandwidth for the broadcast channel, such that the communication overhead can remain substantially the same across all system bandwidths. It should also be appreciated that the terminal (e.g., user equipment 120) has fewer BCH demodulation hypotheses because of the detection of CP duration in the P-SCH code detection.

In yet another aspect, acquisition sequence 775 can alternatively combine information conveyed by the SCH and BCH (FIG. 6). That is, two P-SCH code sequences transmitted at 1.25MHz (which may be mutually orthogonal) facilitate symbol timing detection and BCH bandwidth indication. In addition, frequency synchronization is also performed. The S-SCH channel code sequences are transmitted at 1.25MHz, and frequency reuse is applied to such sequences. Frequency reuse contemplates using various subcarrier sets of all possible subcarriers for transmission from neighboring or peripheral cells. Thus, the sequence frequency (tone) mapping may depend on the reuse factor. In one aspect, for a v < 5MHz system, a value of 1 reuse is employed, e.g., virtually no partitioning is done for all available system subcarrier sets; for a system with Δ v ≧ 5MHz, reuse of a value of 3 is employed, e.g., the available system subcarriers are divided into 3 subsets. For example, in 3G LTE, a wireless transmission system with v-20 MHz may be divided into two groups of 400 subcarriers and one group of 401 subcarriers. The sequence transmitted in the S-SCH can convey 512 hypotheses (cell identities). It should be understood, however, that the cell identity may be transmitted partially on the P-SCH and partially on the S-SCH by transmitting a portion of the 9 bits used for cell identity in the P-SCH and the remaining portion in the S-SCH. In 790, the BCH code sequence is transmitted at 1.25MHz or 5MHz depending on the system bandwidth (fig. 5B), and conveys CP duration, system bandwidth information, and other system information.

It is to be appreciated that after the initial cell acquisition is completed, the terminal (e.g., user equipment 120) can utilize the completed frequency synchronization for neighbor cell search. In the time synchronization system, the terminal that completes cell acquisition performs time synchronization with the neighboring cell, so the detection of the peripheral cell is simplified as follows: cell identities that identify the peripheral cells, and other critical information such as antenna structures of the peripheral cell transmitters. In contrast, in the asynchronous system case, the terminal needs to repeat a complete cell search for the peripheral cells. It should also be appreciated that code sequences transmitted by a base station in connection with cell detection can be stored in memory (e.g., memory 126) within a terminal performing cell acquisition. This information may enable the terminal to seamlessly conduct a cell search under multiple acquisition sequences (e.g., acquisition sequences 725, 750, and 775).

Successful search acquisition by the terminal depends on the channel conditions (e.g., SNR, SINR). A terminal with a poor channel condition indicator may fail to complete cell acquisition and establish a normal wireless communication link with an access point (e.g., base station 140). To increase the likelihood of a terminal successfully performing cell acquisition (synchronization), cell search information may be relayed from a synchronized terminal to a terminal with a poor channel status. Fig. 8A shows a system 800 in which a terminal 120 that has completed cell acquisition (synchronization) relays cell information from a base station 140 in a serving cell 810 to two unsynchronized terminals that may experience poor channel conditions. The exemplary serving cell 810 is hexagonal in shape, but it should be understood that the shape of the cell is determined by the particular arrangement of tiles that covers a particular service area. During cell acquisition, terminal 120 stores P-SCH, S-SCH, and BCH code sequences in a memory (e.g., memory 126). As described above, such a sequence of communicated operating cell information enables a wireless device (e.g., terminal 120) to establish an active communication link 850 with a base station (e.g., base station 140). For synchronization purposes, cell acquisition sequences (e.g., sequences 725, 750, and 775) are passed over link 860₁Is relayed to terminal 815 through link 860₂Is relayed to the terminal 825. The terminals may then become synchronized regardless of channel conditions with the access point (e.g., base station 140). Note that in system 800, terminal 120 continuously transmits synchronization code sequences in substantially the same manner as base stations transmit. Furthermore, the bandwidth employed when relaying P-SCH, S-SCH, and BCH synchronization code sequences need not be the same as the bandwidth employed by the base station (e.g., 1.25MHz or 5 MHz).

Relaying synchronization information, in addition to increasing communication overhead, can also increase the complexity of the terminal (e.g., terminal 120) architecture. To mitigate communication overhead, a terminal may be within a particular time interval (e.g., { Δ τ)_P，Δτ_Q，Δτ_R}) at a particular scheduled time point (e.g., { τ }_P，τ_Q，τ_R}) to relay information as shown in diagram 850 in fig. 6B. It should be understood that these times and time intervals are merely exemplary, ofThe relaying may be performed at other different times and intervals. These times may be stored in a memory of the terminal (e.g., memory 126) or may be terminal-specific — the time intervals take on different values for different terminals depending on the architecture of the terminal (e.g., power resources, antenna structures, etc.). A processor of the terminal (e.g., processor 124) may schedule when to trigger the relay of cell information, which may also trigger the relay of information. In the case where the relay time interval is time-specific, the relay cell information can become asynchronous, and terminal diversity (e.g., the presence of multiple synchronized terminals in the serving cell) can ensure that terminals with lower SNR (e.g., poor reception conditions with respect to geography or climate) can still receive data synchronously while poor communication conditions with the base station persist. Note that the power consumption decay of electromagnetic radiation will be inversely proportional to the square of the distance to the radiation source. Thus, the SNR between a terminal and a base station can be poor, while the SNR between a terminal and a relay terminal (e.g., terminal 120, terminal 835) can be significantly higher because the terminals can be geographically closer.

In addition to (or in a different case than) relaying cell information at a predetermined time, a synchronized terminal (e.g., terminal 120) may receive an indication from a base station to trigger a relay period (e.g.,，Δτ_Q，Δτ_R) The pilot sequence of (1). An artificial intelligence component in the base station can infer when a pilot signal requesting relay cell information is to be transmitted based on channel quality indicators of synchronized terminals in the serving cell that are instantaneous or averaged over time and/or space through statistical-based analysis and/or utility analysis. Note that after sending the "request to relay" pilot signal, the base station may temporarily stop transmitting cell information on the downlink to reduce overhead.

It should be appreciated that the second synchronous relay terminal (e.g., terminal 835) may actively assume the role of relaying data after the first relay terminal (e.g., terminal 120) relays information for a predetermined period of time; subsequently, the other terminals may continue relaying the data. Each relay terminal may have a time-dependent relay profile, as shown in diagram 850 in fig. 8B. In one aspect, cell search relaying may be employed in environments where wireless transmission of voice, video, data, or a combination thereof is a critical task. In one aspect, such an environment may be an urban combat environment, where substantially uninterrupted wireless access to enemy intelligence is at a mission critical level, and SNR is typically low inside buildings and facilities. The base station may be contained in an armored vehicle having a transmitter for wireless communication, providing logistical support to a small group of troops carrying mobile terminals. As the troops perform their tasks, each mobile terminal with a sufficient SNR level may relay synchronization information as the troops enter and leave buildings and facilities (and thus critical low SNR areas with subsequent need for cell acquisition).

Fig. 9A shows a system 900 in which a terminal 920 transmits downlink 960₁-960₃In a neighboring cell 940₁、940₂And 940₃These cells are acquired simultaneously when operating with frequency reuse. In multi-cell synchronization based on frequency reuse, to avoid performance degradation (e.g., throughput reduction) due to employing a subset of subcarriers rather than all subcarriers available to each base station (see exemplary diagram 925 of 12 tones shown in fig. 9B), multi-cell operation employing frequency reuse may be during a particular time (e.g., { Δ τ)₀，Δτ₁，...，Δτ_K}) of a predetermined operating period (e.g., one hour, one day) at a particular point in time (e.g., { τ }₀，τ...，τ_K}) is active. At time intervals [ tau ]_α，τ_α+Δτ_α]Times other than (α ═ 0, 1., K), operation is still performed with all subcarriers. Such time-dependent operation is illustrated in exemplary diagram 950 in fig. 9C. In an aspect, a handoff to frequency reuse operation is made by a handoff existing at each base station (e.g., BS) operating with frequency reuse₁、BS₂And BS₃) Is determined by the processor in (1). A specific time { tau₀，τ₁，...，τ_KAnd time interval Δ τ₀，Δτ₁，...，Δτ_KIs stored in a memory located at each base station operating with frequency reuse.

Fig. 10 illustrates an architecture of a system 1000 in which a user equipment 1020 simultaneously acquires multiple cells (which have cell transmitters 1040) during a frequency reuse operation₁-1040_L). Once the subcarrier sets are selected, the base station (e.g., base station 1040)_KWhere 1 < K < L) maps synchronization channels (P-SCH and S-SCH) and broadcast channel cell acquisition code sequences onto the selected subcarrier set and transmits these codes in the center of the selected subcarrier subset. Terminal 1040_KA terminal-specific bandwidth may be employed for the selected subcarriers. In one aspect, this bandwidth is a minimum between 1.25MHz and the frequency bandwidth of the selected subcarriers. The user equipment 1020 has an architecture that enables it to detect a set of L data streams simultaneously. Such L streams correspond to base station 1040₁-1040_LThe L-order frequencies used for communication reuse the OFDM symbols transmitted on the L subsets of the coinciding subcarriers. Therefore, the user terminal 1020 can acquire L cells simultaneously. The architecture of the terminal 1020 can include a processor 1022, memory 1024, and detection component 1026₁-1026_L. Each of these sensing assemblies operates in substantially the same manner as sensing assembly 122 (see fig. 1, supra). On the other hand, in a particular sector (e.g., in an airplane during a landing, after activation of a building (e.g., a court, some hospital area, etc.) where all terminals are off, multi-cell acquisition in a frequency reuse scenario may be possible if a large number of terminals therein may be synchronized at approximately the same time.

With reference to the exemplary systems shown and described above, methodologies that may be implemented in accordance with the disclosed subject matter will be better appreciated with reference to the flow charts of fig. 11-13. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the number or order of blocks, as some blocks may occur in different orders and/or concurrently with other blocks from what is depicted and described herein. Moreover, not all illustrated blocks may be required to implement the methodologies described hereinafter. It is to be appreciated that the functionality associated with these blocks may be implemented in software, hardware, a combination thereof, or in any other suitable manner (e.g., device, system, process, component, etc.). Additionally, it should be further appreciated that the methodologies disclosed hereinafter and throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to various devices. Those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram.

Fig. 11 shows a flow diagram of a method of performing cell acquisition. In one action, P-SCH, S-SCH, and BCH code sequences carrying cell information are received. Such information may include OFDM symbol boundaries, frequency synchronization, radio frame boundaries, cell identification, cyclic prefix timing, BCH bandwidth indication, system bandwidth and other system information such as base station antenna structure, peripheral cell information, etc. In act 1120, the code sequence is processed, e.g., a correlation timing metric is calculated. In one aspect, such calculations may be performed by a processor located in the user equipment, such as processor 124. In act 1130, the cell information is extracted.

Fig. 12 shows a flow diagram of a method of relaying cell synchronization information. In act 1210, a cell search is conducted in accordance with one or more aspects described herein (e.g., fig. 7A, 7B, or 7C). In act 1220, code sequences for primary and secondary synchronization channels and a broadcast channel are stored. In one aspect, the cell search is performed in act 1210 by storing in memory of the terminal. Such memory may be memory 126. The relaying of cell information is accomplished in act 1230 by transmitting the stored code sequences. In an aspect, a bandwidth employed for transmitting the code sequence is determined by a capability of the user equipment performing the information relaying, and such bandwidth may be different from a bandwidth employed by the base station for communicating the code sequence to the user equipment performing the relaying.

Fig. 13A/13B is a flow diagram of a method for transmitting/receiving cell information using frequency reuse in a cellular wireless communication system. Referring first to fig. 13A, in act 1310, L-order frequency reuse is determined. In an aspect, in OFDMA, such frequency reuse may: selecting L subsets of subcarriers from a total available set of subcarriers compatible with a system bandwidth; subsequent to L cell transmitters (e.g., base station 1040)₁-1040_L(ii) a See also fig. 9) determines the L subsets. Such a determination is typically a result of the operator complying with a wireless communication standard (e.g., 801.11b, 801.11G, 3G LTE). In act 1320, cell information is transmitted using the determined L subsets of subcarriers. Referring now to fig. 13B, in act 1355, cell information from the L subsets of subcarriers is received. In one aspect, the information is detected by a user equipment (e.g., user equipment 1020) having an appropriate architecture to simultaneously detect the P-SCH, S-SCH, and demodulate the BCH for transmission of all L code sequences. In act 1365, cell information is extracted from each of the L subcarrier subsets.

Referring now to fig. 14, illustrated is a system 1400 that can receive a code sequence of primary and secondary synchronization channel symbols. System 1400 can reside at least partially within a wireless device (e.g., user device 120) and include functional blocks that can represent functions implemented by a processor or an electronic machine, software, or combination thereof (e.g., firmware). In particular, system 1400 includes a logical grouping 1410 of electronic components that can act in conjunction. In one aspect, logical grouping 1410 includes an electrical component 1415 for receiving a code sequence of primary synchronization channel symbols (see, e.g., fig. 4) that conveys at least one of a cyclic prefix duration, a portion of a cell identification code, and an indication of a broadcast channel bandwidth and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection. Further, logical grouping 1410 includes an electrical component for receiving one or more code sequences of secondary synchronization channel symbols (see, e.g., fig. 4), wherein the one or more code sequences of synchronization channel symbols convey at least one of a radio frame boundary, a portion or all of a cell identification code, and an indication of a broadcast channel bandwidth. Further, logical grouping 1410 includes an electrical component 1435 for receiving a code sequence of broadcast channel symbols (e.g., see fig. 4), wherein the code sequence of broadcast channel symbols conveys at least one of cyclic prefix timing and wireless system bandwidth. Note that electronics component 1435 also includes: an electrical component 1438 for receiving a code sequence of synchronization channel symbols transmitted at 1.25MHz (see, e.g., fig. 5A); an electronic component 1441 for receiving a code sequence of broadcast channel symbols transmitted at 1.25MHz or 5MHz (see, e.g., fig. 5B).

Additionally, system 1400 can include a memory 1450 that retains instructions for executing functions associated with electrical components 1415, 1425, 1335, 1438, and 1441, as well as data that may be generated during executing such functions. While shown as being external to memory 1450, it is to be understood that one or more of electrical components 1415, 1425, 1335, 1438, and 1441 can exist within memory 1450.

The above description includes examples of one or more aspects. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art may recognize that many further combinations and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

Claims (42)

1. An apparatus that operates in a wireless communication environment, the apparatus comprising:

means for receiving a code sequence in a primary synchronization channel, wherein the code sequence in the primary synchronization channel conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; and

means for receiving one or more code sequences in a secondary synchronization channel, wherein the one or more code sequences in the secondary synchronization channel convey a remainder of the cell identification code.

2. The apparatus of claim 1, wherein one or more code sequences in a secondary synchronization channel further convey a radio frame boundary.

3. The apparatus of claim 1, further comprising means for receiving a code sequence in a broadcast channel, wherein the code sequence in the broadcast channel conveys wireless system bandwidth.

4. The apparatus of claim 1, further comprising means for relaying code sequences in the primary synchronization channel to terminals in a wireless communication system that did not acquire cell information from a cell base station.

5. The apparatus of claim 4, further comprising means for scheduling a time to trigger relaying the code sequence in the primary synchronization channel.

6. The apparatus of claim 5, further comprising means for storing data in a memory, wherein the data comprises a scheduled time to trigger relaying the code sequence in the primary synchronization channel.

7. The apparatus of claim 1, further comprising:

means for acquiring cell information simultaneously within a plurality of subcarrier spacings;

means for processing the plurality of cell information.

8. An apparatus that operates in a wireless communication environment, the apparatus comprising:

means for transmitting a code sequence in a primary synchronization channel, wherein the code sequence in the primary synchronization channel conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection; and

means for transmitting one or more code sequences in a secondary synchronization channel, wherein the one or more code sequences in the secondary synchronization channel convey a remainder of the cell identification code.

9. The apparatus of claim 8, wherein one or more code sequences in a secondary synchronization channel further convey a radio frame boundary.

10. The apparatus of claim 8, further comprising means for transmitting a code sequence in a broadcast channel, wherein the code sequence in the broadcast channel conveys wireless system bandwidth.

11. The apparatus of claim 8, further comprising means for transmitting a code sequence in the primary synchronization channel at 1.25 MHz.

12. The apparatus of claim 10, further comprising means for transmitting code sequences in the broadcast channel at 1.25MHz when system Bandwidth (BW) is less than 5MHz, and at 5MHz when BW is greater than or equal to 5 MHz.

13. The apparatus of claim 8, further comprising means for transmitting a request to relay a code sequence in the primary synchronization channel.

14. The apparatus of claim 9, further comprising means for transmitting a request to relay one or more code sequences in the secondary synchronization channel.

15. The apparatus of claim 10, further comprising means for transmitting a request to relay a code sequence in the broadcast channel.

16. The apparatus of claim 13, further comprising means for temporarily ceasing transmission of code sequences in the primary synchronization channel on a downlink to reduce overhead.

17. The apparatus of claim 14, further comprising means for temporarily ceasing transmission of one or more code sequences in the secondary synchronization channel on a downlink to reduce overhead.

18. The apparatus of claim 15, further comprising means for temporarily ceasing transmission of code sequences in the broadcast channel on a downlink to reduce overhead.

19. The apparatus of claim 8, further comprising means for inferring when to send a request to relay a code sequence in the primary synchronization channel to a synchronization terminal based at least in part on instantaneous or temporally or spatially averaged channel quality indicators for a plurality of synchronization terminals in a serving cell.

20. The apparatus of claim 9, further comprising means for inferring when to send a request to relay one or more code sequences in the secondary synchronization channel to one synchronization terminal based at least in part on instantaneous or temporally or spatially averaged channel quality indicators for a plurality of synchronization terminals in a serving cell.

21. The apparatus of claim 10, further comprising means for inferring when to send a request to relay a code sequence in the broadcast channel to a synchronized terminal based at least in part on instantaneous or temporally or spatially averaged channel quality indicators for a plurality of synchronized terminals in a serving cell.

22. The apparatus of claim 8, further comprising means for scheduling times and time intervals for the apparatus to operate with frequency reuse.

23. A method of operating in a wireless communication environment, the method comprising:

receiving a code sequence of primary synchronization channel symbols, wherein the code sequence of primary synchronization channel symbols conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection;

one or more code sequences of secondary synchronization channel symbols are received, wherein the one or more code sequences of secondary synchronization channel symbols convey a remaining portion of the cell identification code.

24. The method of claim 23, wherein one or more code sequences of secondary synchronization channel symbols further convey a radio frame boundary.

25. The method of claim 23, further comprising:

a code sequence of broadcast channel symbols is received, wherein the code sequence of broadcast channel symbols conveys a wireless system bandwidth.

26. The method of claim 25, further comprising:

receiving a code sequence of synchronization channel symbols, wherein the code sequence of synchronization channel symbols is transmitted at 1.25 MHz;

receiving a code sequence of broadcast channel symbols, wherein the code sequence of broadcast channel symbols is transmitted at 1.25MHz or 5 MHz.

27. A method for use in a wireless communication system, the method comprising:

receiving a code sequence of primary synchronization channel symbols, wherein the code sequence of primary synchronization channel symbols conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection;

receiving one or more code sequences of secondary synchronization channel symbols, wherein the one or more code sequences of secondary synchronization channel symbols convey a remaining portion of the cell identification code;

a code sequence of broadcast channel symbols is received, wherein the code sequence of broadcast channel symbols conveys a wireless system bandwidth.

28. A method for use in a wireless communication system, the method comprising:

transmitting a code sequence of primary synchronization channel symbols at 1.25MHz, wherein the code sequence of primary synchronization channel symbols conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection;

one or more code sequences of secondary synchronization channel symbols are transmitted at 1.25MHz, wherein the one or more code sequences of secondary synchronization channel symbols convey a remaining portion of the cell identification code.

29. A method for use in a wireless communication system, the method comprising:

receiving a code sequence in a primary synchronization channel (P-SCH), wherein the code sequence in the P-SCH conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection;

receiving one or more code sequences in a secondary synchronization channel (S-SCH), wherein the one or more code sequences in the S-SCH convey a remaining portion of a cell identification code;

receiving a code sequence in a Broadcast Channel (BCH), wherein the code sequence in the BCH conveys wireless system bandwidth;

the P-SCH and S-SCH code sequences are processed, and cell information conveyed by the P-SCH and S-SCH code sequences is extracted.

30. The method of claim 29, wherein one or more code sequences in a secondary synchronization channel (S-SCH) further convey a radio frame boundary.

31. The method of claim 29, further comprising:

receiving code sequences in the primary and secondary synchronization channels at 1.25 MHz;

receiving a code sequence in the broadcast channel at 1.25MHz or 5 MHz.

32. The method of claim 29, further comprising:

storing cell information extracted from the primary and secondary synchronization channels and the broadcast channel;

relaying the cell information.

33. The method of claim 29, further comprising: scheduling relaying the cell information.

34. A method for use in a wireless communication system, the method comprising:

transmitting a code sequence of primary synchronization channel symbols, wherein the code sequence of primary synchronization channel symbols conveys a portion of a cell identification code and facilitates orthogonal frequency division multiplexing symbol boundary detection, slot boundary detection, and subframe boundary detection;

transmitting one or more code sequences of secondary synchronization channel symbols, wherein the one or more code sequences of secondary synchronization channel symbols convey a remaining portion of the cell identification code;

transmitting a code sequence in a broadcast channel, wherein the code sequence in the broadcast channel conveys a wireless system bandwidth.

35. The method of claim 34, wherein one or more code sequences in secondary synchronization channel symbols further convey a radio frame boundary.

36. The method of claim 34, further comprising: frequency reuse is employed to transmit the code sequences of primary and secondary synchronization channel symbols and the code sequences of broadcast channel symbols.

37. The method of claim 34, wherein the code sequence of the primary synchronization channel symbols, the one or more code sequences of the secondary synchronization channel symbols, and the code sequence in the broadcast channel are Walsh-Hadamard sequences.

38. The method of claim 34, wherein the code sequence of primary synchronization channel symbols, one or more code sequences of secondary synchronization channel symbols, and the code sequence in the broadcast channel are Gold sequences.

39. The method of claim 34, wherein the code sequence of the primary synchronization channel symbols, the one or more code sequences of the secondary synchronization channel symbols, and the code sequence in the broadcast channel are pseudonoise sequences.

40. The method of claim 34, wherein the code sequence of primary synchronization channel symbols, one or more code sequences of secondary synchronization channel symbols, and the code sequence in the broadcast channel are maximum length sequences (M-sequences).

41. The method of claim 34, wherein the code sequences of the primary synchronization channel symbols, the one or more code sequences of the secondary synchronization channel symbols, and the code sequences in the broadcast channel are generic Chirp-like sequences.

42. The method of claim 34, wherein the code sequence of the primary synchronization channel symbols, the one or more code sequences of the secondary synchronization channel symbols, and the code sequence in the broadcast channel are any combination of Walsh-Hadamard sequences, Gold sequences, pseudonoise sequences, maximal length sequences, and generally Chirp-like sequences.