Rate Compatible Punctured Turbo Research Articles

RATE COMPATIBLE PUNCTURED TURBO-CODED HYBRID ARQ FOR OFDM SYSTEM

Now a day’s orthogonal frequency division multiplexing (OFDM) is under intense research for broadband wireless transmission because of its robustness against multipath fading. A major concern in data communication such as OFDM is to control transmission errors caused by the channel noise so that error free data can be delivered to the user. Rate compatible punctured turbo (RCPT) coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a OFDM system. However the extent to which the RCPT HARQ improves the throughput performance of the OFDM system has not been fully understood. HARQ has been suggested as a means of providing high data rate and high throughput communication in next generation systems through diversity combining transmit attempts at the receiver. The combination of RCPT HARQ with OFDM provides significant bandwidth at close to capacity rates of channel. In this paper, we evaluate by computer simulations the throughput performance of RCPT code HARQ for OFDM system as compared to that of conventional OFDM.

A Switching Type-II Hybrid ARQ Scheme with RCPT Codes

A switching type-II hybrid ARQ scheme with rate compatible punctured turbo (RCPT) codes is proposed in this letter. The proposed scheme combines three retransmission schemes by minimizing a cost function that yields a compromise between throughput and delay time. The performance of the proposed algorithm is evaluated by computer simulations. Compared with conventional hybrid ARQ algorithms, the proposed algorithm can offer almost the same throughput performance with smaller time delay.

Throughput Comparison of Turbo-Coded HARQ in OFDM, MC-CDMA and DS-CDMA with Frequency-Domain Equalization

OFDM, MC-CDMA and DS-CDMA are being researched vigorously as the prospective signaling technique for the next generation mobile communications systems, which will be characterized by the broadband packet technology. With packet transmissions, hybrid ARQ (HARQ) will be inevitable for error control. HARQ with rate compatible punctured turbo (RCPT) codes is one of the promising techniques. Data rate equivalent to the OFDM system can be attained with MC-CDMA and DS-CDMA by assigning all the available codes to the same user resulting in what is commonly referred to as multicode MC-CDMA and multicode DS-CDMA. A rake receiver is used for receiving the DS-CDMA signals. However, recently minimum mean square error frequency-domain equalization (MMSE-FDE) has been proposed for the reception of DS-CDMA signals. In this paper, we introduce RCPT HARQ to DS-CDMA with MMSE-FDE and compare its throughput performance with OFDM, multicode MC-CDMA and multicode DS-CDMA with rake combining. MMSE weight for packet combining is introduced and the soft value generation for turbo coding in MC-CDMA and DS-CDMA with MMSE-FDE is presented. The throughput is theoretically evaluated for the uncoded case. For RCPT-HARQ, the comparison is done by computer simulations. It is found that the throughput of HARQ using DS-CDMA with MMSE-FDE is the same as or better than using MC-CDMA. However, with higher level modulation, type I HARQ using OFDM is better than using either MC-CDMA or DS-CDMA; for type II HARQ without redundancy in the first transmission, however, MC-CDMA and DS-CDMA gives a higher throughput.

A cross-layer optimisation approach for multimedia over CDMA mobile wireless networks

We study a cross-layer optimisation approach for the transport of packetised digital video over future generation CDMA mobile wireless networks, taking into account both the interference-limited and bandwidth-limited characteristics associated with spread-spectrum CDMA systems. In particular, by considering the resource requirements as the aggregate of the products of source coding rates and the energy per information bit to noise ratio, we propose a joint source coding-power control (JSCPC) strategy combined with adaptive channel coding employing the class of rate-compatible punctured turbo (RCPT) codes to provide forward error correction (FEC) with unequal error protection (UEP). We show that this adaptive cross-layer approach can simultaneously maximise the quality of the delivered video while minimising the total resource consumption, thereby providing improved spectral efficiency and network utilisation. We demonstrate the efficacy of this approach using the ITU-T H.263+ video source coder although the approach is generally applicable to other source coding schemes as well.

Application of Rate Compatible Punctured Turbo Coded Hybrid ARQ to MC-CDMA Mobile Radio

MC-CDMA, a multicarrier (MC) modulation scheme based on code division multiple access (CDMA), is the most likely candidate for the next generation of mobile radio communications. The rate compatible punctured turbo (RCPT) coded hybrid automatic repeat request (HARQ) has been found to give improved throughput performance in a direct sequence (DS) CDMA system. However, the extent to which the RCPT HARQ improves the throughput performance of an MC-CDMA system has not been fully understood. In this paper, we apply the RCPT HARQ to MC-CDMA and evaluate by computer simulations its performance in a frequency selective Rayleigh fading channel. We found that the performance of RCPT HARQ MC-CDMA is almost insensitive to channel characteristics. The performance can be drastically improved with receive diversity combined with space-time transmit diversity. In addition, the comparison of RCPT HARQ MC-CDMA, orthogonal frequency division multiplexing, and DS-CDMA shows that under similar conditions the throughput of MC-CDMA is the best in a frequency selective fading channel.

Turbo-coded ARQ schemes for DS-CDMA data networks over fading and shadowing channels: throughput, delay, and energy efficiency

Modified ARQ (automatic-repeat-request) techniques based on turbo coding are investigated for asynchronous DS-CDMA (direct-sequence code-division multiple-access) data networks under shadowing and frequency selective fading channel conditions. The throughput, delay, and energy efficiency performance of standard ARQ, metric combining, and RCPT (rate compatible punctured turbo) coded ARQ schemes are compared via simulations. The RCPT/ARQ schemes are shown to outperform the other two schemes in terms of both throughput and energy efficiency at the cost of larger delay and complexity. In addition, maximum network throughput is investigated for different ARQ schemes under energy constraints.

On the performance of hybrid FEC/ARQ systems using rate compatible punctured turbo (RCPT) codes

This paper introduces a hybrid forward-error correction/automatic repeat-request (ARQ) system that employs rate compatible punctured turbo (RCPT) codes to achieve enhanced throughput performance over a nonstationary Gaussian channel. The proposed RCPT-ARQ system combines the performance of turbo codes with the frugal use of incremental redundancy inherent in the rate compatible punctured convolutional codes of Hagenauer (1988). Moreover, this paper introduces the notion of puncturing the systematic code symbols of a turbo code to maximize throughput at signal-to-noise ratios (SNRs) of interest. The resulting system provides both an efficient family of achievable code rates at middle to high SNR and powerful low-rate error correction capability at low SNR.