Multiple ARQ Processes for MIMO Systems

Abstract

<p/> <p>We propose a new automatic repeat request (ARQ) scheme for MIMO systems with multiple transmit and receive antennas. The substreams emitted from various transmit antennas encounter distinct propagation channels and thus have different error statistics. When per-antenna encoders are used, separating ARQ processes among the substreams results in a throughput improvement. Moreover, it facilitates the interference cancellation in certain MIMO techniques. Quantitative results from UMTS simulations demonstrate that the proposed multiple ARQ structure yields more than 30% gain in link throughput.</p

Performance analysis of two-user cooperative ARQ protocol over Rayleigh fading channel

“…Throughput is defined as the ratio between the number of information bits correctly transmitted by a user and the time that the channel is allocated to that user in a multi-user system [18,27]. Hence, the throughput can be calculated as follows:…”

DSC and universal bit-level combining for HARQ systems

“…As for the proposed DST-based schemes, the complexity is mainly decided by the complexity of BPAs calculations and combinations. In (3), N (S 2 ) = 1 2 M (M − 1) and N (S 1 ) = M, the complexity of (3) is thus approximately O (M 2 t), and the complexity of (5) is almost the same with (3) except the computation of exponential function. The complexity of (7), (8), and (9) From the above analyses, although the total complexity of the proposed combining schemes is larger than ML and MAP, the total complexity is polynomial or non-exponential with M and t. And with this penalty of complexity, the performance of the proposed schemes is improved at a considerable extent, which can be seen in the above subsections.…”

“…The efficiency of the system can be improved if the ARQ is combined with a forward-error-correcting (FEC) code, referred to as HARQ, which includes Chase combining [1] and incremental redundancy (IR) [2]. There are many HARQ strategies: including separating the HARQ process into HARQ sub-processes that operate over an isolated pairing of a transmitter and receiver antenna [3]; the constellation rearrangement technique [4] and the bit rearrangement scheme [5] that can provide a kind of diversity for performance improvement. In [4,5], authors developed effective HARQ strategies at the transmitter in order to improve the system reliability.…”

Multiantenna Technology for High-Speed Wireless Internet Access

“…As an added beneÞt, layered architectures may offer interesting synergies with upper layers on the data n T n T =4 and communication protocol. 32 These incentives, however, come at the expense of reduced robustness because now each signal must be decoded without support from the others, which are conveying independent data. Furthermore, errors in the detection of each of the signals may propagate through the interference cancellation process and adversely impact the detection of other signals.…”