Abstract: Disclosed is a system and method for demodulating packet data channels with multiple Walsh codes in a CDMA mobile communication system supporting voice and packet data services. A plurality of fingers process signals received from a transmitter as inputs, perform despreading and channel compensation with spreading codes pre-assigned to the transmitter, and outputting the despread chip signals. A chip combiner combines the chip signals output from the plurality of fingers. A chip buffer stores the combined chip signals until decoding of the packet data control channels is completed and information on the multiple Walsh codes assigned to the packet data channels. Then, a multiple Walsh demodulator generates at least one Walsh symbol performing Walsh decovering of the combined chip signals using information on the multiple Walsh codes. Therefore, the system can efficiently demodulate data transmission channels using the multiple Walsh codes, and thus complexity of the system and demodulation time can be reduced.

Abstract: A method and apparatus is provided for efficient processing of signal in a communication system. The processing of the signal for transmission may include encoding a block of data at an encoding rate 1/R. The encoding produces R number of data symbols for every data bit in the block of data. A block of RAM (299, 600) is partitioned into a plurality of blocks of RAM to allow reading simultaneously data symbols from the plurality of blocks of RAM to produce an in-phase and a quad-phase data symbols simultaneously. At least two scramblers (306 and 307) are used for simultaneously scrambling the in-phase and quad-phase data symbols. A Walsh covering/summing block (700) followed by the scramblers provides efficient Walsh covering and summing of signals for a combined transmission from the communication system.

Abstract: In a method for controlling call access of a terminal in a mobile communication system based on cellular communication system, call access of mobile terminals can efficiently be controlled depending on the state of individual resources of Walsh code classes assigned to each mobile terminal from the base station and the state of a reverse link in a communication system which supports multi-transmission rate depending on service options of the mobile terminals.

Abstract: An interleaver memory access apparatus of a CDMA system including an interleaver memory for storing code symbols to be transmitted; a shift register unit for simultaneously receiving 18 bit code symbols from the interleaver memory and outputting the 18 bit code symbols in three sets of 6 bit code symbols; an index decoding unit for decoding the 6 bit code symbols outputted from the shift register unit and generates a Walsh bit index; an address generator and control logic for controlling an access operation of the interleaver memory and the input and output operation of the shift register unit and the index coding unit; and an orthogonal modulator for outputting 64 bit Walsh codes based on the Walsh bit index outputted from the index decoding unit.

Abstract: The invention discloses a pilot synchronization channel structure for mobile communication systems. The channel structure includes a pilot channel overlapping a synchronization channel (SCH), defined in the wideband code division multiple access (WCDMA) protocol. Each frame of the pilot channel consists of plural time slots. Each time slot is packed with pre-selected pilot symbols, after spread spectrum and scrambling. The overlap can be defined as search code of one symbol length with pilot signal of m?1 symbols length by intermittent overlap. The overlap can also be defined as search code of one symbol length with pilot signal of m symbols length by continuous overlap. The invention combines organically both CDMA 2000 and WCDMA standards to provide better pilot and synchronization functions.

Abstract: The code space associated with the communication system is divided into at least two subspaces where each subspace is assigned to a different mode of operation. In one mode, such as a voice mode, each user is given full time access to a portion of the subspace associated with that mode of operation. In a second mode, such as a data mode, each user uses the entire subspace associated with that mode on a time shared basis. Additionally, in-sector handoffs from one Walsh code to another are used to more efficiently distribute the code space.

Abstract: Many communications protocols involve a collection of communication channels collectively forming the dimensions of a finite dimensional vector space, of which at any point in time, only a subset of those channels or dimensions must be received. Messages on these channels are time progressions in at least the actively used dimensions of the vector space which have been linearly transformed to create a sample list transported across at least one physical transport layer to a receiver. The linear transform may further include an estimation of the effects of the transport of the sample list across the one or more physical layers to the receiver. This invention uses at least portions of pseudo-inverses of the linear transform in various ways within receivers and receiver portions of transceivers.

Abstract: A channel spreading device for a CDMA communication system is disclosed.

Abstract: In a high data rate communication system, a method and apparatus for selectively reducing the power of signals transmitted by an access terminal. The access terminal generates an access metric based on throughput or data rate control (DRC) information. The access terminal then compares the access metric to an access metric threshold and gates or reduces its transmit power based on the results of the comparison. The access terminal uses algorithms to determine the access metric and access metric threshold that reduce transmit power during periods when the access terminal would not be selected to receive data from an access network according to an access network selection algorithm.

Abstract: A device for allocating a forward common channel in a CDMA (Code Division Multiple Access) communication system, including: a plurality of channel transmitters; a storage medium for storing, as orthogonal code numbers for the forward common channel used in a second CDMA communication system, orthogonal code numbers which cannot maintain an orthogonality due to an orthogonal code that the forward common channel uses at a maximum data rate, the orthogonal code being used in a first CDMA communication system; and a controller for reading the orthogonal code numbers from the storage medium according to mobile station type information from a mobile station, and allocating a specific forward common channel such that forward common channel message is spread and transmitted by a corresponding one of the channel transmitters with a specific one of the read orthogonal code numbers.

Abstract: The invention is a modulation system that encodes symbols in accordance with a modulation code which, for a given communications channel, produces a signal that at the decoder includes maximized sample timing information in each encoded symbol. For systems that use PLLs to control a sample timing clock, the sample timing information is the average or squared slope. The modulation code used for a given system is selected based on the target response h(x) of the associated communications channel, such that h (x)*rk exceeds a predetermined threshold value, where “*” represents convolution and rk is a modulation code symbol. To reduce the bit overhead, or code rate, the inventive modulation system provides more modulation code symbols at the start of a data block, or sector, when system jitter is expected to be relatively high in response, for example, to the movement of a read head.

Abstract: A method for operating an IS-OFDM system for point-to-point wireless communications that suppresses narrow-band interference comprises the steps of producing and transmitting an IS-OFDM signal including the use of parallel-to-serial converters in order to maintain the same data rate for the transmission as the input data rate. The method further comprises the steps of receiving and recovering an IS-OFDM signal.

Abstract: Pilot signals transmitted by different antennas in a wireless communication system using multiple transmit antennas are distinguished using different codes. In one embodiment, each of two antennas simultaneously transmit a time slot's worth of data while time division multiplexing a pilot signal with the data. The pilot signal from the first antenna is encoded with a first code such as a Walsh code and the pilot signal from the second antenna is encoded with a different code such as a different Walsh code. The different codes enable a receiver to distinguish the pilot signals when they are received to enable coherent detection of signals transmitted by both of the antennas.

Abstract: A novel and improved method for implementing a high-transmission-rate over-the-air interface is described. A transmit system provides an in-phase channel set and a quadrature-phase channel set. The in-phase channel set is used to provide a complete set of orthogonal medium rate control and traffic channels. The quadrature-phase channel set is used to provide a high-rate supplemental channel and an extended set of medium rate channels that are orthogonal to each other and the original medium rate channels. The high-rate supplemental channel is generated over a set of medium rate channels using a short channel code. The medium rate channel is generated using a set of long channel codes.

Abstract: Methods and apparatus are presented for acknowledging broadcast transmissions. An acknowledgment channel is designed for acknowledging the success or failure of a transmission on a dedicated channel and on a broadcast channel. Acknowledgments are generated based on whether a new orthogonal space is sent to a remote station or not. Moreover, an acknowledgment to the broadcast transmission is generated when an acknowledgment is needed for a dedicated transmission. The two acknowledgments are combined and sent to a base station.

Abstract: A method of improving bandwidth of wireless CDMA systems by shuffling the rows of a Hadamard function in a pseudo-random manner. A Hadamard function is used to provide orthogonality between users. The orthogonal waveforms are used to prevent interference from different users sharing the same cell as well as multiple channels from the same user. The rows of the Hadamard function are shuffled in a pseudo-random manner. This effectively maximally spreads the spectral density of the transmitted signal out across the available spectrum. These codes are pre-computed and stored in lookup tables of mobile wireless devices. The data signals are modulated by one set of codes. Thereby, one data bit can be transmitted per chip.

Abstract: A code indexing system for a CDMA communication station that uses orthogonal variable spreading factor (OVSF) codes has a single number mapped to each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, the system provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.

Abstract: A station capable of receiving information containing Walsh coding for a plurality of channels and canceling interference from the received information and the method of cancellation. A memory is provided for storing received signals containing a Walsh code for each of a plurality of channels as well as reflected and/or refracted versions of said received signals and a first plurality of signal paths is provided which are selectively coupled to the memory. The signal paths apply corresponding delays and inverse Walsh code transformations to separate the channels. Further, cancellation of the channels interfering with a desired channel proceeds with complementary delays and Walsh code transformation to regenerate the interference which is subtracted from the received signal in memory.

Abstract: A code indexing system for a CDMA communication station that uses orthogonal variable spreading factor (OVSF) codes has a single number mapped to each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, the system provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.

Abstract: A method of allocating optimum orthogonal function codes to a reverse link in a communication system which has one base station and a plurality of mobile stations, comprising the first step of detecting characteristics of reverse channels from a desired one of the mobile stations to the base station, the second step of obtaining an orthogonal function code based on the detected characteristics of the reverse channels, and the third step of allocating the obtained orthogonal function code to the desired mobile station. According to the present invention, optimum Walsh codes are allocated for distinction between mobile station signals of the reverse link to minimize an interference between mobile stations in a CDMA communication system. Therefore, an inter-mobile station interference through a multipath can be minimized to significantly enhance a signal-to-noise ratio of the reverse link.

Abstract: In one disclosed embodiment, an input bit stream is supplied to a trellis code block. For example, the trellis code block can perform convolutional coding using a rate 6/7 code. The output of the trellis code block is then modulated using, for example, trellis coded quadrature amplitude modulation with 128 signal points or modulation symbols. The sequence of modulation symbols thus generated can be diversity encoded. The diversity encoding can be either a space time encoding, for example, or a space frequency encoding. The sequence of modulation symbols, or the sequence of diversity encoded modulation symbols, is fed to two or more orthogonal Walsh covers. For example, replicas of the modulation symbol sequences can be provided to increase diversity, or demultiplexing the modulation symbol sequences can be used to increase data transmission rate or “throughput”. The outputs of the Walsh covers are fed as separate inputs into a communication channel.

Abstract: Packets are generated for delivery over a forward communication channel from a base station to a remote station, in which a parameter that characterizes the packets being generated is determined adaptively based on factors not limited to the data rate of the channel.

Abstract: A plurality of data channels provide respective data rates and maximum error rates from a mobile station to a base station of a CDMA system; a pilot channel facilitates recovery of the data channels. For each data channel there is determined a channel energy to noise ratio (ENR) and a required pilot channel ENR. A maximum one of the required pilot channel ENRs is selected as an ENR for transmission of the pilot channel. A relative gain, and hence transmit signal power, for each data channel is determined from the ENR determined for the data channel and the selected maximum ENR for transmission of the pilot channel, thereby minimizing the total transmitted signal power of the mobile station. The data channel signals are spread using orthogonal Walsh codes and are combined with their determined relative gains.

Abstract: A method and apparatus for high data rate communication in a cellular/PCS communication system is provided. Specifically, the embodiment provides for early assignment of code channel for signaling channels (F-DCCH) in soft handoff. Thus, rather than simultaneously assigning a code channel for signaling data and another for traffic data for a particular Mobile Station (MS) in soft handoff, the code channel is assigned earlier for signaling data. Some of the unnecessary Base Station (BS) procedures with respect to the signaling data may be eliminated. An embodiment includes the concept of early signaling from the MS to request a code channel for signaling data, optionally followed by signaling (at a later time) from the MS to request a code channel for traffic data. This permits the MS to have the F-DCCH in soft handoff before having the F-DTCH (Forward Dedicated Traffic Channel) in soft handoff without requiring the BS to skip any of its procedures.

Abstract: A demodulation method in a mobile station having a plurality of channels, for receiving a signal from a base station. In one aspect, the base station has a plurality of channels, a BPSK spreader for orthogonally spreading symbol data of each channel with an assigned orthogonal code, and a QPSK spreader for PN-spreading the orthogonally spread signal with a PN code. In the demodulation method, a first QPSK despreader in the mobile station receives PN-spread signal and PN-despreads the PN-spread signal with the PN code, and a second QPSK despreader orthogonally despreads the PN-despread signal with a complex orthogonal code having the real and imaginary parts of the assigned orthogonal code. In another aspect, the base station has a plurality of channels, a QPSK spreader for spreading symbol data of each channel by the real and imaginary parts of its assigned orthogonal code, and a QPSK spreader for PN-spreading the orthogonally spread signal with a PN code.

Abstract: Apparatus for a transmitter and a receiver which enhance the performance of a system coherent demodulation by utilizing non-pilot sub-channels to enhance the accuracy of estimates of amplitude and phase noise inherent in the transmission channel is described. This enhancement is accomplished by utilizing the corrected received data on a fundamental channel to enhance a pilot channel estimate, which is subsequently utilized by a dot product module in demodulating a supplementary data channel.

Abstract: A method for deep paging in a communication system employing orthogonal channelizing codes, such as Walsh sequences, of predetermined length m, that does not require a high powered paging channel. The method includes the steps of generating a paging channel message which is combined with a Walsh sequence having a length greater than or equal to 2m, and transmitting the paging channel message at a data rate of less than 4800 bits per second (bps). By transmitting the paging channel message at a low data rate and integrating collected energy over a period longer by a factor on the order of 1000, the message is able to penetrate buildings and other structures or high attenuation environments, thereby allowing one to successfully page a user terminal that is inside such a structure or area. Preferably, the paging channel message is formed using an auxiliary Walsh sequence on the order of 65536 chips in length, and the data rate is less than 10 bps.

Abstract: A method for generating a complex quasi-orthogonal code for channel spreading in a CDMA communication system is disclosed.

Abstract: A power control device for a CDMA communication system using different kinds of spreading codes. In the power control device for a base station device, a first channel generator generates a first channel signal by spreading first input data with an orthogonal code and a second channel generator generates a second channel signal by spreading second input data with a quasi-orthogonal code. The second channel signal has a gain higher than that of the first channel signal. A first gain controller controls power of the first channel signal and a second gain controller controls power of the second channel signal. An adder adds the first channel signal to the second channel signal, and a spreader spreads a signal output from the adder with a pseudo-random noise (PN) code.

Abstract: In a transmit diversity apparatus for a mobile communication system and a method thereof in accordance with the present invention, by varying forward channel coding and modulation methods according to a forward channel quality and transmitting a transmit symbol by a transmit diversity method such as a STTD and a STD, it is possible to improve forward channel transmit rate, obtain transmit diversity gain and improve error performance simultaneously.

Abstract: A method of determining useable combinations of variables for transmitting a subpacket of an encoder packet in a communication system is disclosed. First, an arbitrary combination from a plurality of all combinations of transmission variables is selected based on a number of currently useable Walsh codes and channel environment. Next, an arbitrary MPR is determined based on a number of useable encoder packet bits, a number of useable slots, and the number of currently useable Walsh codes, all of which belong to the selected arbitrary combination transmission variables. Thereafter, a final MPR, which is the smallest one of MPR values of a MPR set that corresponds to the number of useable encoder packet bits and the number of useable slots, is determined, and a final number of Walsh codes is calculated based on the number of useable encoder packet bits, the number of useable slots, and the determined final MPR.

Abstract: In signal detection system and method implemented to reduce the effects of interference in multi-user detection systems, a receiver defines a frame of symbols containing at least one window based upon a number of user signals contained in a received signal r(t). A symbol amplitude of a single-user in the multi-user system is approximated over the window of the frame based on a number of reflected signal paths of the received user signal. A perturbative correction value is calculated based upon a correlation matrix. An estimation of the symbol amplitude of the single-user signal is calculated over one or a number of windows of the frame. The single-user signal is detected when the symbol amplitudes of the entire signal within the frame has been calculated. To reduce the number of interfering users in a multicell CDMA system, the symbol codes are modified to include an even code and an odd code.

Abstract: A code indexing system for a CDMA communication station that uses orthogonal variable spreading factor (OVSF) codes has a single number mapped to each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, the system provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.

Abstract: A method of time division multiplexing for a forward data packet channel includes encoding parallel data sub-packets into parallel streams of turbo codes; interleaving each of the parallel streams of turbo codes to generate parallel streams of quasi-complementary turbo codes; modulating the parallel streams of quasi-complementary turbo codes to generate parallel streams of modulated data symbols; and multiplexing the parallel streams of modulated data symbols by one of multiplexing and non-complete puncturing to generate a single stream of modulation symbols.

Abstract: A method and apparatus for receiving orthogonal signals in a spread-spectrum communications system. A demodulator provides groups of de-spread samples of a processed received signal. The groups of de-spread samples are passed through an orthogonal code transformer to provide sequential transformer blocks. The blocks are buffered in sequences of 2 or 3. Then each buffered sequence is subjected to a summing, squaring and selection operation a to obtain a desired orthogonal code from each of the transformer blocks of the two or three transformer blocks.

Abstract: Space-time block code with structure of a block STTD. 2×2 blocks allow partial orthogonality for low-complexity detection and optimized diversity gain and coding gain.

Abstract: Disclosed is a method and apparatus for enhancing diversity gain without reducing data rate by increasing the number of antenna elements and configuring the antenna elements for improving signal-to-noise ratio at a receiver. The antenna array comprise a first antenna group with at least two antenna elements and a second antenna group with at least one antenna element. The first and second antenna groups are spaced approximately ten carrier wavelengths or more apart from each other, and the antenna elements belonging to the first antenna group are spaced approximately a half carrier wavelength or less apart from each other. A plurality of data streams is generated from a signal and used to produce a first and second plurality of representative data streams. Each of the first plurality of representative data streams is phase-shifted and encoded using different orthogonal codes.

Abstract: Methods and apparatus to improve the speed and reliability of decoders are presented herein. Namely, a priori knowledge of Walsh space information is used to increase the speed at which messages are decoded. In systems where control messages contain transmission parameters of concurrently transmitted packet data, a faster demodulation and decoding of control messages allows a receiver to demodulate the packet data sooner, so that a shorter buffer is needed to store the received packet data. The receiver uses the Walsh space from the previous successfully decoded message to first decode the current message. If the decoding attempt is unsuccessful, the receiver then uses a neighboring Walsh space to decode the current message.

Abstract: A vector-based Walsh code sequence generator (100) provides for a general architecture that can be easily adapted to any random length sequence and any random number of bits per access. The Walsh code sequence generator (100) can produce a new access on every hardware clock cycle, thereby maximizing the efficiency of the bit sequence requesting process.

Abstract: A method of allocating frame offset and link in a base station in which performance of digital telecommunications system is enhanced by allocating a resource in such a manner that loads of the link and frame offset are dispersed when communication channels for use of handoff are allocated, and soft handoff can be occurred when the frame offset is allocated, has an advantage in that the link and frame offset are dynamically allocated when requesting handoff so that loads can be evenly distributed between the link and the frame offset. Thus, data loss between the communication channel and the control station may be minimized, and the mobile station may timely perform handoff, thus enabling a stable call handling service.

Abstract: In a wireless transmission system that transmits the same information in parallel using two or more different types of modulation schemes, such as a satellite-based digital audio transmission system transmitting two TDM signals and a single OFDM signal, a receiver processes the differently modulated signals to generate separate demodulated signals that are then combined to form a single combined signal for further processing (e.g., decoding). In one embodiment, the receiver applies a maximal ratio combining (MRC) technique to generate a single optimal ratio combined signal from the differently modulated signals. By combining the differently modulated signals using an MRC technique, the adverse affects of noise related to inter-symbol interference in the individual signals can be reduced and the complexity of hardware in the receiver can be reduced.

Abstract: Modulation codes for code division multiple access (CDMA) cellular communications systems that are mutually orthogonal may be generated as a sequence of Walsh codes. A method of assigning Walsh codes includes the steps of (404) receiving as input a status vector (200) for a Walsh code system of length 2n and a selected Walsh code length j=2n-k; (406)-(418) creating a new status vector for a selected Walsh code length of j from the status vector; (416) creating a search mask for the selected Walsh code length j; (418) creating a search sequence for the selected Walsh code length j; and (434)-(442) searching the search sequence for the next available Walsh code. The status vector is updated (500) to track the assignment and release of each Walsh code of each Walsh code length in the Walsh code system.

Abstract: In a mobile communication system, a coding apparatus receives 5 information bits and generates a code symbol stream comprised of 20 coded symbols. The coding apparatus generates 5 coded symbol streams having a length 32 by encoding the 5 individual information bits with different Walsh codes having a length 32, and generates a coded symbol stream comprised of 32 coded symbols by XORing the 5 coded symbol streams in a symbol unit. Further, the coding apparatus generates a code symbol stream comprised of 20 coded symbols by puncturing 2nd, 4th, 5th, 6th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, and 30th coded symbols among the 32 coded symbols.

Abstract: A method and apparatus for transmitting and receiving between MSs and a BS orthogonal code index information indicating orthogonal codes available to the MSs in a mobile communication system supporting multimedia services including voice and data services. The MSs are connected to the BS and receive a data service simultaneously from the BS. The BS generates the orthogonal code index information according to the forward channel states of the MSs, and transmits it to the MSs. Each of the MSs determines its assigned orthogonal codes from received orthogonal code index information.

Abstract: A message that has its energy spread over a frame of encoded data is decoded. First, encoded data are received so as to obtain a quantity of the encoded data that is less than all the encoded data in the frame and also is less than all the encoded data representing the message. Then, the quantity of encoded data received is supplemented, without receiving additional encoded data, so as to obtain a frame of data. Typically, the data will be supplemented by zero padding the data, such as by initializing a frame buffer to all zeros and then overwriting the zero data with actual data as it is received. Finally, ordinary frame decoding is performed on the frame of data so generated, in order to decode the message.

Abstract: A code indexing method for orthogonal variable spreading factor (OVSF) codes introduces a single number mapped to the each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, it provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.

Abstract: A method and apparatus for space-time coding signals for transmission on multiple antennas. A received input symbol stream is transformed using a predefined transform and transmitted on a first set of N antennas. The same input symbol stream is then offset by M symbol periods to generate an offset input symbol stream. The offset input symbol stream is then transformed using the predefined transform and transmitted on a second set of N antennas. A third through Xth set of N antennas may be utilized for transmission by successively offsetting the offset input symbol stream by an additional M symbol periods for each additional set of N antennas used, before performing the transform and transmitting on the additional set of N antennas.

Abstract: A code indexing method for orthogonal variable spreading factor (OVSF) codes introduces a single number mapped to the each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, it provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.

Abstract: A communication system is used to transmit and receive a plurality of relatively narrow-band signals and wideband signals. The two signal types share a common electromagnetic spectrum by employing spreading gain and maintaining orthogonality between simultaneously transmitted wideband and narrow-band signals. Signal orthogonality is maintained by selectively choosing orthogonal codes and aligning or spacing a wideband carrier frequency with respect to the narrow-band carrier frequencies in accordance with the ratio of the wideband to the narrow-band chip frequencies. A pilot signal is preferably transmitted contemporaneously with the transmission of the first spreaded signal, and a control data signal, associated with a plurality of users on the first bandwidth, is transmitted on a common control channel using a single Walsh code that is shared by a plurality of users in a TDMA protocol.

Abstract: An improved spread spectrum communication system includes a transmitter and a receiver utilizing a pilot channel for the transmission of pure rather than modulated PN codes for code acquisition or tracking purposes with a lower bit error rate. The pilot signal is used to obtain initial system synchronization and phase tracking of the transmitted spread spectrum signal. At the transmitter side, Walsh an orthogonal code generator, a Walsh modulator, a first PN code generator, a first band spreader, a second band spreader, finite impulse response filters, digital-to-analog converter, low-pass filters, an intermediate frequency mixer, a carrier mixer, a band-pass filter are used to transmit a spread spectrum signal.