Abstract: A serial Viterbi decoder having a chainback cache is provided for use in a mobile telephone. In one embodiment described herein, the decoder includes a branch error metric block, an add-compare-select unit, and a chainback block including a chainback RAM, a full chainback cache and chainback controller circuitry. The chainback cache caches decision bits from previous process cycles such that full chainback operations need not always be performed. The chainback cache is configured to cache on all reads. With the chainback cache, significant savings in power consumption and processing time may be achieved with only a relatively modest increase in the amount of circuitry required. In another embodiment, a full chainback cache is not provided. Rather, the chainback block instead includes an L+1 bit RAM, an updown counter and a shift register configured to emulate a chainback cache.

Abstract: A method and apparatus for controlling the transmission of signals from one or more of a plurality of mobile stations to a base station on a plurality of M multiple access channels. A power control information packet formed from a plurality of power control bits is transmitted from the base station to the one or more mobile stations. Each of the power control bits in the power control information packet has a position that is mapped to a selected access channel and to a time offset within the selected access channel. The power control information packet is received at a first mobile station. A message is then transmitted from the first mobile station to the base station on a first access channel and at a first time offset associated with the first access channel. The message is transmitted from the first mobile station at a power level determined in response to a first power control bit in the power control information packet.

Abstract: A method for determining the location of a mobile unit within a cellular system. A synchronized signal at a common phase is generated at each base station in a system. The mobile unit transmits a signal tone. Each base station compares the phase of the signal tone to the common phase of the synchronized signal to produce a phase offset. A system controller compares the difference between the phase offset of a first base station and the phase offset of a second base station and determines the difference in distance between the first base station and the mobile unit and the second base station and the mobile unit defining a hyperbolic curve of locations. The system controller determines the intersection of the first and second hyperbolic curves thus determining the location of the mobile unit. The mobile station transmits the signal tone on a second channel that is distinct from a first channel over which user information is transmitted.

Abstract: A communication network having a plurality of subscriber units that receive a finite resource from a common node is disclosed. Individual subscriber units may seize the finite resource of the common node to the exclusion of all other subscriber units in the network. A scheduler allocates the finite resource to the individual subscriber units based upon a weight associated with the individual subscriber units. The scheduler determines the weight for each of the subscriber units based upon an instantaneous rate of consuming the finite resource.

Abstract: The signal strength of a received signal in a communication system is estimated by the measured signal strength of a desired signal which is transmitted from a source device to a destination device. The energy of the desired signal and the energy of the noise are measured or computed. The measured signal strength can be computed by dividing the energy of the desired signal with the energy of the noise. The signal strength of the desired signal can be estimated as the maximum likelihood estimate of the actual signal strength &agr;. The signal strength of the desired signal can also be estimated based on the expected value of the energy of the desired signal. The signal strength of the desired signal can further be estimated based on the expected value of the energy of the desired signal and accounting for a predetermined bias.

Abstract: A method for determining the position of a mobile station using a base station having three antennas. The first antenna is used to transmit a first signal modulated with a first preassigned Walsh code. The second antenna is used to transmit a second signal modulated with a second preassigned Walsh code. A third antenna is used to transmit a third signal modulated with a third preassigned Walsh code. Each of the three signals is also modulated with a common spreading code in addition to the first, second and third Walsh codes. Each of the three signals are received by the mobile station. The mobile station determines the time of arrival of each such signal. Based upon these relative times of arrival, the mobile station determines its location.

Abstract: An apparatus and method for locating a remote station in a synchronous communications network using the time of arrival of a reference pilot signal at the remote station as a time reference. The time difference of arrival (TDOA) of GPS signals received by the remote station and other signals received from a base station, are measured relative to this reference time. From these measurements, the location of the remote station is determined. The invention treats the location issue as a TDOA problem.

Abstract: A method and apparatus for rate determination in a communication system using orthogonal rate-dependent Walsh covering codes. Orthogonal rate-dependent Walsh codes are used to cover repeated code symbols prior to transmission over a communication link. In one embodiment, the Walsh codes comprise orthogonal binary codes that increase by powers of two for each data rate used in the system. Code symbols are repeated and then covered at the symbol rate using the inventive orthogonal Walsh codes. The inventive code symbol repetition and encoding method and apparatus is particularly advantageous in encoding data that contains long sequences of logical zeros and ones. The orthogonal nature of the code symbols encoded in accordance with the present invention allows use of a more accurate and less complex data rate determination apparatus in the receiver. Rate determination is thereby improved resulting in an improvement in data service capability and a reduction in decoding errors.

Abstract: A multi-path, split, multi-stage vector quantizer (MPSMS-VQ) having multiple paths between stages which result in a robust and flexible quanitizer. By varying parameters, the MPSMS-VQ meets design requirements, such as: (1) the number of bits used to represent the input vector (i.e., uses the same or less total bits than the given number of bits, N); (2) the dimension of the input vector, the performance (distortion as noted by WMSE or SD); (3) complexity (i.e., total complexity can be adjusted to be within a complexity constraint); and (4) memory usage (i.e., total number of words M in the codebook memory can be adjusted to be equal to, or less than, the memory constraint M.sub.d). Therefore, the disclosed method and apparatus works well in many conditions (i.e., offers a very robust performance across a wide range of inputs).

Abstract: A read/write electronic memory bank 10, including a plurality of memory units 22-28 and 12-18 which receive a common clock signal having a repetitive clock cycle and have a common input port 20, 21 and a common output port 30, 31. The units function such that in each clock cycle an input word is written to the memory bank 10 from the input port 20, 21 and an output word is read from the memory bank 10 to the output port 30, 31. Each memory unit 22-28 and 12-18 includes a single-port random-access memory (RAM) device 22-28 and a first-in first-out (FIFO) buffer 12-18, such that when the output word is to be read from the same memory unit 22-28 and 12-18 to which the input word is to be written in a given clock cycle, one of the input and output words is passed between the respective port 20, 21, 30, 31 of the memory bank 10 and the FIFO buffer 12-18, instead of between the respective port 20, 21, 30, 31 of the memory bank 10 and the RAM device 22-28.

Abstract: A method and apparatus for minimizing the amount of time that a mobile station is to be out of communication with an "origination" base station while searching for a suitable system to which to perform a mobile station assisted hard handoff. After being directed to search for pilot signals in an alternate frequency band, the mobile station tunes to that alternate frequency and samples the incoming data, storing those samples in memory. When a sufficient number of samples have been stored, the mobile station retunes to the origination frequency. The forward link data is again received by the mobile station, and reverse link data can be successfully transmitted to the origination base station. After retuning to the origination frequency, a searcher in the mobile station will subsequently be employed to search for pilot signal offsets utilizing the stored data collected from the alternate frequency.

Abstract: A method and apparatus for efficiently transmitting location assistance information to a mobile communication device over a control channel with a minimal impact on the capacity of the control channel. A position location server provides a difference between satellite locations which have been computed using Almanac data and then Ephemeris data. Sending only the difference between the locations and satellite clock corrections computed using the two different data types, the total amount of information to be transmitted to a mobile communication device is significantly reduced. Furthermore, by providing rate of change information, the method and apparatus allows the location assistance information to remain valid for a relatively long time after it is has been received by the mobile communication device.

Abstract: A system and method for determining a position of a mobile wireless transceiver. The inventive system merges GPS position location and wireless communication technologies to achieve a precise position location in dense urban and other environments when line-of-sight to the satellites is somewhat obscured. The inventive method uses signals from only two GPS satellites and the serving terrestrial base station. In a most general sense, the inventive method includes the steps of receiving at a base station a first signal transmitted from a first GPS satellite and a second signal transmitted from a second GPS satellite. The mobile transceiver is adapted to receive these GPS signals as well and transmit a third signal to the base station in response thereto. The base station receives the third signal and uses it to calculate the position of the wireless unit. In a specific implementation, the base station sends aiding information to the wireless unit.

Abstract: A method and apparatus for efficiently transmitting location assistance information to a mobile communication device over a control channel with a minimal impact on the capacity of the control channel. A position location server provides a difference between satellite locations which have been computed using Almanac data and then Ephemeris data. Sending only the difference between the locations and clock corrections computed using the two different data types, the total amount of information to be transmitted to a mobile communication device is significantly reduced. Furthermore, by providing rate of change information, the method and apparatus allows the location assistance information to remain valid for a relatively long time after it is has been received by the mobile communication device.

Abstract: A method for determining the position of a mobile station within a cellular telephone system having first and second base stations. A round trip signal propagation time between the first base station and the mobile station is measured at the first base station. A first signal is transmitted from the first base station to the mobile station, and a second signal is transmitted from the second base station to the mobile station. An arrival time difference representing a time interval between a first relative time when the first signal is received at the mobile station and a second relative time when the second signal is received at the mobile station is measured at the mobile station. The position of the mobile station is determined in accordance with the round trip propagation time and the arrival time difference.A method for determining the position of a mobile station within a cellular telephone system having first and second base stations.

Abstract: A computer is coupled to a switching subsystem that connects the computer to either a network interface device or a wireless modem. The network interface device sends a status signal to the switch indicating whether the device is connected to the network. If a network connection is made, the network interface device is used to communicate over the network. If the status indication is that the network interface device is not connected, the switch automatically connects the wireless modem to the computer so that the computer can communicate with the network over a radio channel. In a preferred embodiment, the switching subsystem reconnects to the network port when it again becomes operable.

Abstract: A method and apparatus for performing inter-system hard handoff between communication systems or inter-frequency hard handoff within a CDMA communication system is disclosed. The purpose of this invention is to reduce the probability of dropped calls during inter-system hard handoff. In the event that a hard handoff attempt is unsuccessful, the mobile station will return to the original system with information which the communication system of the present invention uses to assist in the performance of future handoff attempts. Alternatively, with no handoff attempt made, the mobile station monitors the destination system then returns to the original system with information used to assist in subsequent handoff attempts. The information returned from monitoring a CDMA system consists of results of a search for one or more pilots given at offsets in a specific list provided to the mobile station by the base station or a set of offsets based upon a predetermined search algorithm.

Abstract: A method and apparatus for controlling the transmit power of a high rate code division multiple access (CDMA) link is described. The channel condition to a subscriber unit is evaluated and the configuration of a high rate link in soft handoff is based on the channel condition. If a fading channel is detected the supplemental channels of the high rate link are transmitted from multiple base stations. If a non-fading channel is detected the supplemental channels of the high rate link are transmitted from a single base station. Parameters monitored to determine the channel condition include the pilot strength, pilot code offset and error rate.

Abstract: A bandpass .SIGMA..DELTA. DC utilizing either a single-loop or a MASH architecture wherein the resonators are implemented as either a delay cell resonator, a delay cell based resonator, a Forward-Euler resonator, or a two-path interleaved resonator. The resonator can be synthesized with analog circuit techniques such as active-RC, gm-C, MOSFET-C, switched capacitor, or switched current. The switched capacitor or switched current circuits can be designed using single-sampling, double-sampling, or multi-sampling circuits. The non-stringent requirement of a .SIGMA..DELTA. ADC using switched capacitor circuits allows the ADC to be implemented in a CMOS process to minimize cost and reduce power consumption. Double-sampling circuits provide improved matching and improved tolerance to sampling clock jitter. In particular, a bandpass MASH 4-4 .SIGMA..DELTA. ADC provides a simulated signal-to-noise ratio of 85 dB at an oversampling ratio of 32 for a CDMA application. The bandpass .SIGMA..DELTA.

Abstract: A novel and improved method and apparatus for switching the radio interface layer of a wireless telephone call from code division multiple access (CDMA) cellular to GSM time division multiple access (TDMA) cellular during the course of that telephone call or other communication is described. In accordance with one embodiment of the invention, a set of base stations operating in accordance with the GSM standard generate pilot beacons signals in accordance with CDMA technology. During a phone call, a subscriber unit detects CDMA pilot signals, and notifies a base station controller when CDMA pilot signals are detected and the strength at which they are received. The base station controller identifies CDMA pilot signals from CDMA pilot beacon, and initiates a CDMA to GSM handover via the generation of a set of signaling messages which instruct the subscriber unit and receiving GSM infrastructure equipment to prepare for the switching of the radio interface layer.