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

algorithmics and modular computations, Theory of Codes and Cryptography (3).From an analytical 1. RE Blahut. Theory and practice of error control codes. eecs.uottawa.ca/∼yongacog/courses/coding/ (3) R.E. Blahut,Theory and Practice of Error Control Codes, Addison Wesley, 1983. QA 268. Cached. Download as a PDF 457, Theory and Practice of Error Control CodesBlahut 1984 (Show Context). Citation Context..ontinued fractions.

Theory and practice of error control codes

In this paper, we investigate an optimal power loading algorithm for an OFDM-based cognitive radio (CR) system. The downlink transmission capacity of the CR user is thereby maximized, while the interference introduced to the primary user (PU) remains within a tolerable range. We also propose two suboptimal loading algorithms that are less complex. We also study the effect of a subcarrier nulling mechanism on the performance of the different algorithms under consideration. The performance of the optimal and suboptimal schemes is compared with the performance of the classical power loading algorithms, e.g., water-filling and uniform power but variable rate loading schemes that are used for conventional OFDM-based systems. Presented numerical results show that for a given interference threshold, the proposed optimal scheme allows CR base station (BS) to transmit more power in order to achieve a higher transmission rate than the classical loading algorithms. These results also show that although the proposed suboptimal schemes have certain degradation in performance compared to the optimal scheme, they outperform the classical loading algorithms. We also present numerical results for nulling mechanism. Finally, we investigate the effect of imperfect channel gain information at the transmitter.

Optimal and Suboptimal Power Allocation Schemes for OFDM-based Cognitive Radio Systems

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

Recent advances in satellite technology are making possible the development of broadband satellite access (BSA) systems for two-way access to multimedia Internet services. This article provides an overview of BSA systems with an emphasis on resource management and interworking techniques to support IP-based multimedia services. The article draws on collaborative research performed over the past few years as part of the Broadband Satellite Communications Major Project of the Canadian Institute of Telecommunications Research. Some key innovations are described: combined free/demand assigned multiple access (CFDAMA) for dynamic satellite bandwidth allocation; an architecture for DiffServ provisioning over BSA systems; and a dynamic TCP Vegas protocol as a proxy service for split-TCP connections over BSA systems.

Interactive multimedia satellite access communications

A versatile Reed-Solomon (RS) decoder structure based on the time-domain decoding algorithm (transform decoding without transforms) is developed. The algorithm is restructured, and a method is given to decode any RS code generated by any generator polynomial. The main advantage of the decoder structure is its versatility, that is, it can be programmed to decode any Reed-Solomon code defined in Galois field (GF) 2/sup m/ with a fixed symbol size m. This decoder can correct errors and erasures for any RS code, including shortened and singly extended codes. It is shown that the decoder has a very simple structure and can be used to design high-speed single-chip VLSI decoders. As an example, a gate-array-based programmable RS decoder is implemented on a single chip. This decoder chip can decode any RS code defined in GF (2/sup 5/) with any code word length and any number of information symbols. The decoder chip is fabricated using low-power 1.5- mu , two-layer-metal, HCMOS technology. >

A versatile time-domain Reed-Solomon decoder

The design of the codec for the ATCS radio data link is considered. The code is defined. The encoding algorithm, the decoding algorithm, and Galois field arithmetic are discussed. Implementation of the Reed-Solomon codec as a stand-alone system in order to provide a possibility of real-time bit-rate measurement is discussed. The implementation of this codec using three different 8-b and 16-b microprocessors/microcomputers is described. Their complexity and throughput are discussed. >

Design of Reed-Solomon (16,12) codec for North American Advanced Train Control System

The structure, implementation, and potential application of a gate-array-based programmable Reed-Solomon encoder/decoder (codec) chip set is presented. The encoder is based on a transform encoding scheme. The decoder is based on a modified version of the time-domain decoding (transform decoding without transform) algorithm. This algorithm has a regular structure, which is important for VLSI implementation. The structure and its implementation based on VLSI gate-array CMOS technology are described. The decoder can correct both errors and erasures for standard for shortened systematic and transform code words. The decoding time is independent of the number of errors or erasures in the received word. The Reed-Solomon codec can be used as a stand-alone (ST) device or as a microprocessor peripheral (MP) component. In MP mode, the codec can be directly interfaced to any 8-b, 16-b or 32-b, standard microprocessor, microcontroller, or digital signal processor (DSP). In ST mode, the codec operates as a standalone device, directly in the data symbol stream. It does not require a processor or any external buffer. >

A gate-array-based programmable Reed-Solomon codec: structure-implementation-applications

Two hybrid schemes of time-frequency resource sharing to increase the rain margin of Ku-and Ka-band satellite systems are proposed. Scheme 1 requires sharing a small pool of bandwidth for adaptive forward error control coding, sharing a small pool of time frame for rate reduction, and sharing a portion of low frequency time-division multiple access (TDMA) back-up frame for downlink transmission to the rain affected stations. Scheme 2 utilizes variable rate modulation and forward error correction, shares a small pool of time frame for rate reduction, and shares a portion of low frequency TDMA back-up frame. Effective usable capacities of the system using these schemes are calculated. Distribution of resources in order to maximize the effective usable capacity is also analyzed. The results obtained are compared with other adaptive schemes. Preliminary analysis shows that the utilized capacity of scheme 1 exceeds 99 percent of the effective usable capacity possible if it never rains for an outage of 0.05 percent and fade margin of 2.5 dB. For scheme 2 similar performance is achievable at a fade margin of 1.5 dB. For higher outage objectives the loss of effective utilized capacity is higher for scheme 2.

T. Le-Ngoc

Papers

Interactive multimedia satellite access communications

A versatile time-domain Reed-Solomon decoder

Design of Reed-Solomon (16,12) codec for North American Advanced Train Control System

A gate-array-based programmable Reed-Solomon codec: structure-implementation-applications

Adaptive Forward Error Control for Digital Satellite Systems