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1.
Instead of waiting for the acknowledgments from all the copies of a single data block sent, as in the optimum generalised stop-and-wait ARQ scheme, the transmitter in the proposed scheme starts sending an optimum number of copies of the next block in the queue, soon after receiving the positive acknowledgment from the receiver, thereby further improving the throughput efficiency. 相似文献
2.
The authors propose a new hybrid type II ARQ scheme based on the simple multidimensional concatenated zigzag code. Owing to the fact that the error-correcting capability of zigzag codes is far better than that of conventional convolutional codes, the throughput of our scheme is better than existing hybrid ARQ schemes 相似文献
3.
A method is presented to construct rate-compatible convolutional (RCC) codes from known high-rate punctured convolutional codes, obtained from best-rate 1/2 codes. The construction method is rather simple and straightforward, and still yields good codes. Moreover, low-rate codes can be obtained without any limit on the lowest achievable code rate. Based on the RCC codes, a generalized type-II hybrid ARQ scheme, which combines the benefits of the modified type-II hybrid ARQ strategy of J. Hagenauer (1988) with the code-combining ARQ strategy of D. Chase (1985), is proposed and analyzed. With the proposed generalized type-II hybrid ARQ strategy, the throughput increases as the starting coding rage increases, and as the channel degrades, it tends to merge with the throughput of rate 1/2 type-II hybrid ARQ schemes with code combining, thus allowing the system to be flexible and adaptive to channel conditions, even under wide noise variations and severe degradations 相似文献
4.
In the letter a generalised stop-and-wait ARQ technique with soft error detection is proposed which achieves a higher throughput efficiency with respect to other modified ARQ schemes recently described in the literature. An optimisation of the throughput efficiency is carried out to obtain a better performance. 相似文献
5.
A stop-and-wait ARQ protocol is described, in which the modulation operation is strictly integrated into the transmission procedure. The data blocks are sent to the receiver in groups containing a specified number of consecutive copies. The optimum number of transmissions per codeword, which maximises the throughput, is evaluated. The results show that a net improvement can be achieved by using the described algorithm with respect to other similar ARQ schemes. In particular, it is shown that for high error rates this stop-and-wait scheme presents higher throughput than the classical selective protocol 相似文献
6.
Yuwei Chang 《Communications, IEEE Transactions on》1995,43(7):2169-2171
7.
The letter investigates the throughput performance of stop-and-wait ARQ schemes, whereby multiple contiguous copies of each data block are sent instead of one single copy. In particular, the influence of combining several copies of the same block for the decision at the receiver side is studied by means of a simple model. Explicit formulas are obtained 相似文献
8.
Mobile communication channels are frequently plagued by severe noise and disturbances such as multipath fading and doppler effects that severely degrade performance. Among the automatic-repeat-request (ARQ) protocols used to improve the communication channel reliability, the stop-and-wait (SW) is positively characterized by simple implementation and negatively by low throughputs. This work describes the application of some new SW protocols that retain the simple implementation of the classical SW schemes, while reducing the transmitter's wait state time to increase throughput. The performance of the modified SW protocols, derived through computer simulations, is shown to be comparable to that of more complex ARQ protocols. 相似文献
9.
This paper presents an analytical model for the study of Hybrid ARQ techniques on Discrete Time Markov Channels by means of an appropriate Markov chain, which tracks the transmission outcome and can be used to evaluate several performance metrics, including throughput, loss probability, number of retransmissions, and delay. The analysis is carried out with the assumptions that the information frame is encoded by the source with a linear block code and hard decoding is used at the receiver side. We finally present numerical evaluations for the performance of a truncated Type II Hybrid ARQ technique based on Reed Solomon erasure codes. 相似文献
10.
This paper describes the design and performance of a novel adaptive hybrid ARQ scheme using concatenated FEC codes for error
control over wireless ATM networks. The wireless links are characterized by higher, time‐varying error rates and burstier
error patterns in comparison with the fiber‐based links for which ATM was designed. The purpose of the hybrid ARQ scheme is
to provide a capability to dynamically support reliable ATM‐based transport over wireless channels by using a combination
of our ARQ scheme (called SDLP) and the concatenated FEC scheme. The key ideas in the proposed hybrid ARQ scheme are to adapt
the code rate to the channel conditions using incremental redundancy and to increase the starting code rate as much as possible
with the concatenated FEC, maximizing the throughput efficiency. The numerical results show that our proposed scheme outperforms
other ARQ schemes for all SNR values.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
A type II hybrid automatic repeat request scheme is considered as a retransmission strategy in a direct-sequence code-division multiple-access packet mobile radio network. An analysis based on equilibrium point analysis is presented to model the behavior of the system in a message-based traffic generation model. A simulation approach is introduced to validate the proposed analytical model, obtaining results that closely match those derived theoretically. 相似文献
12.
13.
A hybrid automatic-repeat-request system combined with adaptive forward error correction (ARQ/AFEC) which adaptively alters the error-correcting capability according to channel state using a nonsystematic Reed-Solomon code is presented. lt is shown that the system can alter the error-correcting capability by varying the number of information symbols fed to the decoder only, and not change the hardware of the encoder. Performance evaluations indicate that the ARQ/AFEC system has much higher frame efficiency than ARQ without AFEC for low-bit error rate and has high frame efficiency in a wide range of bit error rates 相似文献
14.
Bigloo A.M.Y. Gulliver T.A. Wang Q. Bhargava V.K. 《Selected Areas in Communications, IEEE Journal on》1994,12(5):917-924
This paper considers the application of rate-adaptive coding (RAC) to a spread spectrum multiple access (SSMA) communication system. Specifically, RAC using a variable rate Reed-Solomon (RS) code with a single decoder is applied to frequency-hopped SSMA. We show that this combination can accommodate a larger number of users compared to that with conventional fixed-rate coding. This increase is a result of a reduction in the channel interference from other users. The penalty for this improvement in most cases is a slight increase in the delay (composed of propagation and decoding delay). The throughput and the undetected error probability for a M-ary symmetric channel are analyzed, and performance results are presented 相似文献
15.
Richard Demo Souza André Gustavo Degraf Uchôa Marcelo Eduardo Pellenz 《AEUE-International Journal of Electronics and Communications》2010,64(11):1078-1081
A novel HARQ scheme using turbo codes is proposed. The method jointly utilizes diversity combining, partial retransmission, and power scaling. Computer simulations and density evolution analysis show that the new method outperforms equal gain diversity combining and soft information combining techniques for a wide Eb/N0 range. 相似文献
16.
Ji-Seob Sim Won-Sik Yoon 《Electronics letters》1998,34(24):2303-2304
A new scheme for adjusting the code rates of RS (Reed-Solomon) and CPC (complementary punctured convolutional) codes to match the channel conditions is proposed for wireless asynchronous transfer mode (WATM). The main feature of this scheme is that all retransmitted sequences are self-decodable. The proposed scheme increases the error correcting capability of RS and CPC codes and uses different code rates for the header and payload of the ATM cell according to the type of data 相似文献
17.
An efficient multicast hybrid ARQ scheme is proposed by incorporating the generalized minimum distance (GRID) decoding of maximum distance separable (MDS) codes with Metzner's (1984) scheme. Erroneous frames are stored in the receiver buffer and recovered after receiving one or more redundant frames. The throughput and the average transmission delay of the proposed scheme are analyzed on memoryless symmetric channels. The proposed scheme can circumvent the degradation of the throughput due to an increase of the number of receivers, which is the most serious defect in the conventional multicast ARQ schemes, at the expense of the transmission delay 相似文献
18.
Reliability-based hybrid ARQ 总被引:12,自引:0,他引:12
A new hybrid automatic repeat request (ARQ) scheme that utilises reliability estimates generated by soft-input, soft-output (SISO) decoders is proposed. The proposed ARQ scheme transmits, additional information for the unreliable bits, and this information is used to perform additional decoding. Results are presented that show this ARQ technique can provide performance close to the channel capacity 相似文献
19.
20.
A soft combining approach utilising symbol-by-symbol maximum a posteriori probability decoding is proposed for hybrid automatic repeat request schemes. In comparison to an existing soft combining approach, significant reductions in post-decoding bit error rate can be obtained without sacrificing the throughput efficiency. This is achieved with the proposed method by accumulating the signal-to-noise ratio at the channel output on each additional retransmission, for use in calculating extrinsic log-likelihood ratios on subsequent decoding attempts. 相似文献