Abstract: A detector selector and method are provided for selecting among detectors, where a less complex detector detects known symbols in a received signal, and a bit error rate for the known symbols is used to determine whether the less complex detection method is sufficient. If the less complex detector is not sufficient, a more complex detector is used to detect the signal. Additionally, assured symbols are used as known symbols to increase the accuracy for the determination of whether the less complex detector is sufficient.

Abstract: A delay-and-add filtering technique positions one or more filter nulls substantially at points of narrowband interference in a relatively wideband received signal. For example, the technique is useful in removing adjacent channel interference in a received W-CDMA signal caused GSM radio transmissions.

Abstract: Biasing soft output values based on a known or learned bit error rate function yields performance improvements in decoding algorithms adapted to work with soft values, such as soft output Viterbi algorithms (SOVA). For example, in a wireless receiver, the soft output values output from a signal demodulator may be biased to reflect the changes in bit error rate across a given burst or block of data. Such changes might arise, for example, due to increasing inaccuracies in the receiver's channel estimate, which is typically computed at the beginning or middle of a block of received data. The wireless receiver may store a table of scaling factors corresponding to the expected bit error rate distribution of the received signal. The table may be preloaded into the receiver, or may be determined during operation. In either case, the table may be updated during operation to reflect bit error incidence observed during operation.

Abstract: A signaling protocol for an infrastructureless short range communication system uses slow frequency hopping compatible with the industrial/scientific/medical (ISM) frequency spectrum. The signaling protocol utilizes a multi-tiered structure having an acknowledgment request frame (200), ping frame (300), connect frame (400) and voice frame (500). These frames are used to determine an appropriate allocation of frequency spectrum from an initiating station (11') to at least one other non-initiating station (11). The signaling protocol allows an initiating station (11') to rapidly identify other stations (11) within a talk group (13) and resolve actual and/or potential collisions to establish clear and reliable infrastructureless communication.

Abstract: A radio communication system (10) has multiple transceivers (12, 14) attempting to initiate communications on a shared communication channel substantially simultaneously. A method for detecting and handling potential channel use collisions is provided for an initiating transceiver (12, 14). The transceiver (12, 14) transmits on the communication channel, a message including an identifying code word. The transceiver (12, 14) then receives data in a predetermined slot of the communication channel, and compares this data with the code word transmitted. A channel use collision is detected when the data received is not equal to the code word transmitted.

Abstract: A method and apparatus is provided for a operating a radio system (100) on shared communication channels. The system (100) has a sequence of communication channels (205), including a reservation channel, and a channel hopping protocol for operating on the sequence (205). A hop period is defined for the channel hopping protocol. The reservation channel is monitored for at least the channel hop period to find an open communication slot indicated by the absence of a reservation signal (320, 325, 330). Communications is then established within the open slot, and channel hopping occurs through the sequence of communication channels in the open slot (345, 350). The slot is preserved by transmitting a reservation signal on the reservation channel, when operating on the reservation channel (355, 360).

Abstract: A method and apparatus is provided for a operating a radio communication system (100). The system (100) has a sequence of communication channels (205), including a reservation channel, and a channel hopping protocol for operating on the sequence (205). A hop period is defined for the channel hopping protocol. A transceiver (113) monitors the reservation channel to find an open communication slot (213), having a duration less than the channel hop period, and cyclically channel hops through the sequence of communication channels in the open slot (213). The transceiver (113) reserves the communication slot (213) for a subsequent cycle through the sequence by transmitting a reservation signal on the reservation channel.

Abstract: A radio communication system (10) operates over a sequence of communication channels using a synchronized channel hopping protocol. A first communication device (16) is provided which is capable of communicating over the sequence of communication channels using channel hopping, and which has an operating communication channel. A second communication device (13) is provided, which is capable of determining the operating communication channel and channel hopping parameters of the first communication device (16). The second communication device (13) can communicate over the sequence of communication channels using channel hopping synchronized with the channel hopping of the first communication device (16), while selecting an operating communication channel different from the operating communication channel of the first communication device (16) when both communication devices (13, 16) operate simultaneously.

Abstract: In a CDMA communication system (100) capable of communicating between a receiver (10) and a transmitter (20)direct sequence spread spectrum communication signals (30), a system and method for synchronizing receiver chip timing and transmitter chip timing. Transmitter (10) transmits a training bit sequence (31) coded with a spreading chip sequence. The receiver (20) adaptively determines a representation of a despreading chip sequence using a tapped delay line equalizer (400). The representation of the despreading chip sequence is represented by tap coefficient potentials of the equalizer (400). Receiver chip timing offset is determined based on the tap coefficient potentials.

Abstract: A communication method in an adaptive CDMA communication system (100) capable of communicating a direct sequence spread spectrum communication signals which comprise bit sequences coded with spreading chip sequences. The method includes the steps of transmitting a DS-SS communication signal (30) having a training bit sequence (31) coded with spreading chip sequence. The method includes the step of despreading the DS-SS communication signal based on the training bit sequence (31) during a training interval. The DS-SS communication signals is despread by adaptively determining a despreading chip sequence. Then, following the training interval determining chip timing offset during a chip timing interval. Finally, bit timing offset is determined during a bit timing interval following the chip timing interval.

Abstract: A code division multiple access (CDMA) communication system (10) having a plurality of spreading codes including a control code includes a first communication device (100) and a second communication device (106). The first communication device is adapted for transmitting a signal spread by the control code inclusive of a request for an optimum spreading code. The second communication device (106) includes a receiver (202) and an adaptable match filter (204) for identifying the optimum spreading code. A transmitter (2024) transmits information about the spreading code to the first communication device 100. With the information on the optimum spreading code available, the first communication device (100) and the second communication device (106) continue to communicate with each other. The optimum spreading code is periodically updated by the first communication device (100) and second communication device (106) to provide for changes in the utilization of codes.

Abstract: A code division multiple access (CDMA) communication system (10) for reuse of available spreading codes includes a first communication device (100) and a second communication device (106). The first and second communication devices (100, 106) are capable of identifying spreading codes and operating frequencies that are optimum for their respective radios. The identity of the optimum spreading code and the frequency of the optimum frequency is communicated from one communication device (100) to another (106), hence allowing the two devices to communicate with each other using their respective optimum codes and frequencies. These codes and frequencies may be periodically updated to provide reusability of codes. By dynamically updating codes and frequencies without the use of a central station, the efficiency and reusability of codes in the CDMA system (10) is significantly enhanced.

Abstract: In a CDMA communication system (100) capable of communicating between a receiver (20) and a transmitter (10) direct sequence spread spectrum communication signals (30), a system and method for synchronizing receiver bit timing and transmitter timing. Transmitter (10) transmits a training bit sequence (31) followed by a transmitter bit timing sequence (33). The receiver (20) adaptively determines a representation of a despreading chip sequence using a tapped delay line equalizer (400). Receiver bit timing offset is determined based on the representation of the despreading chip sequence and the transmitter bit timing sequence (33).