In a data communication system capable of variable rate transmission, high rate packet data transmission improves utilization of the forward link and decreases the transmission delay. Data transmission on the forward link is time multiplexed and the base station transmits at the highest data rate supported by the forward link at each time slot to one mobile station. The data rate is determined by the largest C/I measurement of the forward link signals as measured at the mobile station. Upon determination of a data packet received in error, the mobile station transmits a NACK message back to the base station. The NACK message results in retransmission of the data packet received in error. The data packets can be transmitted out of sequence by the use of sequence number to identify each data unit within the data packets.

Method and apparatus for high-rate packet data transmission

A laptop device includes a personal computer, a cellular transceiver, a speakerphone, and a hybrid communications control unit. The device has connectors for attaching a headset, cellular control unit, land telephone line, and additional speakers and microphones. The micro-processor-controlled hybrid communications control unit includes a modem, a data access arrangement, and a tone generator as well as digital, analog, and power switches. The hybrid communications control unit switches the communications components and provides, under program control, the proper protocols, level, and impedance matching to connect the modem, speakerphone, headset, speaker/microphone, or cellular control unit to the landline or to the cellular network via the transceiver. Matching and switching operations are automatic and transparent to the user. The unit can also connect two of the terminal devices or connect the cellular and landlines for call relaying. The device is capable of connecting plural calls at the same time. The hybrid communications control unit may be controlled by its internal firmware, by toggle switches, or by commands issued from the personal computer.

Portable hybrid communication system and methods

An adaptive scheme for trellis-coded modulation of MPSK signals, called adaptive trellis-coded multiple-phaseshift keying (ATCMPSK), is proposed for slowly Rayleigh fading channels. The adaptive scheme employs a slightly modified rate 1/2 convolutional encoder and the corresponding Viterbi decoder to realize a family of codes of different rates which are employed according to channel conditions. During poor channel conditions, trellis-coded QPSK (TCQPSK) together with repetition schemes are employed. As channel conditions improve, higher rate schemes such as trellis-coded 16 PSK are used. An interleaving/ deinterleaving method suitable for the adaptive scheme is proposed. Theoretical bounds for the error performance and an exact expression for the throughput of the proposed adaptive scheme are derived, and are compared against simulation results. Simulations have been performed to measure the performance of the scheme for different parameters and some nonideal conditions. It is shown that ATCMPSK results in considerable improvement in bit-error-rate (BER) performance of MPSK signals. Under ideal conditions, gains in the range of 3-20 dB are achieved over conventional fixed rate pragmatic trellis-coded schemes.

Adaptive trellis-coded multiple-phase-shift keying for Rayleigh fading channels

In an exemplary communication system, a multiplicity of mobile terminals are to share a communication link with a host processor communicating through base transceivers. The mobile terminals evaluate communication signals being transmitted to one or more of the mobile transceivers and according to the evaluation of such signals, each mobile terminal independently selects a relatively high data rate or a lower more conservative data rate for communication with the host processor. The mobile terminal enters a dormant state after a fixed period elapses during which the mobile unit is not engaged in communication with the base station. Periodically, the mobile terminal reenters active state in receive mode for a brief interval and if no polling signal or other message directed to the mobile terminal is present, the mobile terminal returns to dormant state. When a signal is directed to the mobile terminal, the mobile terminal remains in active receive mode until a fixed period after a communication session is completed and then returns to dormant/active cycling. A base station utilizing a dormant polling protocol transmits polling sequences to a plurality of remote transceivers during periods of heavy loading. During periods of low loading, the base station stops polling and enters into a dormant state, listening for communication request from the remote transceivers. Upon receiving such a request, the base station immediately responds by servicing the requesting remote transceiver. In this way, the base station provides optimized utilization of the communication channel during periods of heavy and light loading conditions.

Remote radio data communication system with data rate switching

Improved apparatus for a radio communication network having mobile transceiver units in communication with base transceiver units. The radio communication network is adaptive in that in order to compensate for the wide range of operating conditions, a set of variable network parameters are adapted for communication between transceivers in the network. These parameters may, for example, define optimized communication on the network under current network conditions. Examples of such parameters may include, without limitation: packet size, data rate, type of modulation, type or degree of error correction coding and spread spectrum communication parameters.

Radio frequency communication network having adaptive communication parameters

The performance of an adjustable source/channel codec in a cellular mobile-radio environment is investigated. The speech transmission rate and the amount of forward error correction change in response to changing channel conditions. The channel rate is constant at 32 kb/s, and when the channel is good all of these bits are used for speech transmission. In intermediate and poor channels the speech rate is 24 or 16 kb/s, and the remaining channel symbols are used for forward error correction. Relative to conventional transmission this approach offers an improved grade of service. For example, the outage rate (the proportion of "poor or worse" communications) goes from nine percent with fixed-rate to three percent with variable-rate transmission. Alternatively, this improved grade of service can be exchanged for higher bandwidth efficiency. The fixed-rate system (with nine percent outage) has 23 users per cell. With 52 users per cell the outage of the variable-rate system is only six percent.

http://ieeexplore.ieee.org/iel5/25/34063/01623095.pdf

Quality of service and bandwidth efficiency of cellular mobile radio with variable bit-rate speech transmission

We have investigated the performance of an adjustable source/channel codec in a cellular mobile-radio environment. The speech transmission rate and the amount of forward error correction change in response to changing channel conditions. The channel rate is constant at 32 kb/s and when the channel is good all of these bits are used for speech transmission. In intermediate and poor channels the speech rate is 24 or 16 kb/s and the remaining channel symbols are used for forward error correction. Relative to conventional transmission this approach offers an improved grade of service. For example, the outage rate (the proportion of "poor or worse" communications) goes from 9% with fixed-rate to 3% with variable-rate transmission. Alternatively, this improved grade of service can be exchanged for higher bandwidth efficiency. The fixed-rate system (with 9% outage) has 23 users per cell. With 52 users per cell the outage of the variable-rate system is only 6%.

https://ieeexplore.ieee.org/iel5/10802/34065/01623155.pdf

C.-E.W. Sundberg

Papers

Quality of service and bandwidth efficiency of cellular mobile radio with variable bit-rate speech transmission

Quality of service and bandwidth efficiency of cellular mobile radio with variable-bit-rate speech transmission