We propose a 2Nr MIMO ARQ scheme that uses multi-strata space-time codes composed of two layers. The phase and transmit power of each layer are assigned adaptively at each transmission round to mitigate the inter-layer interference and improve the block error rate by retransmission. Simulation results show that the proposed scheme achieves better performance than the conventional schemes in terms of the throughput and the block error rate.

Coordinated multi-point processing at multiple base stations can improve coverage, system throughput, and cell-edge throughput for future cellular systems. In this paper, we study the coordinated reception of transmitted signals at multiple MIMO base stations to exploit cooperative diversity. In particular, we propose to employ cooperative multicell automatic repeat request (ARQ) protocol via backhaul links. The attractiveness of this protocol is that processing between coordinated base stations can be made completely transparent to the mobile user, and it improves the mobile user's link reliability and throughput significantly compared to noncooperative ARQ protocol. In our proposed protocol, we consider the scenario where the multicell processing involves one of the following three schemes: decode-and-forward, amplify-and-forward, and compress-and-forward schemes. We derive the average packet error rate and throughput for these cooperative multicell ARQ protocols. Numerical results show that the cooperative multicell ARQ protocols are promising in terms of average packet error rate and throughput. Furthermore, we show that the degree of improvement depends on the type of cooperative multicell ARQ protocol employed and the operating average signal-to-noise ratio of the main and backhaul links.

Recently, network coding (NC) has been popularly applied to wireless networks in order to improve scarce wireless capacity. In wireless LANs, NC can be applied to packet retransmission, and a base station can simultaneously retransmit multiple packets destined to different wireless stations by a single retransmission trial. On the other hand, NC creates additional packet delay at both base station and wireless stations, and hence, packet transfer delay may increase seriously. However, existing NC-based retransmission methods do not consider this additional delay explicitly. In addition, when the number of flows is small, NC exhibits less benefit because the chances of NC-based retransmission are highly reduced. Therefore, in this paper, we propose a novel NC-based retransmission method in order to improve packet transfer delay and jitter of received packets. Moreover, to achieve further improvement of delay, jitter and retransmission efficiency even when there exist a small number of traffic flows, we propose a retransmission method in which NC-based retransmission cooperates with the typical ARQ method. We overcome the disadvantage of NC-based retransmission by combining with ARQ cooperatively. Finally, we show the effectiveness of the proposed methods by extensive computer simulation.

Cooperative transmission protocols attract a great deal of attention in recent years as an efficient way to increase the capacity of multi-hop wireless networks in fading environments. In this paper, we propose and analyze a cooperative transmission method, called Cooperative-Aided Skipping multi-Hop protocol (CASH), for multi-hop wireless networks with Rayleigh fading environments. For performance evaluation, we compare and verify the results of the theoretical analysis with the results of simulations.

This paper presents design and analysis of an Automatic Repeat reQuest (ARQ) scheme for enhancing the throughput and reliability of broadband wireless access systems. The impact of ARQ is emphasized in terms of early error recovery, when Internet data applications and the TCP protocol are considered over a point-to-multipoint fixed wireless system. A selective repeat type ARQ scheme is designed and analyzed through extensive, realistic modeling and simulation of the entire network protocol stack and the wireless channel. The system-wide impact of ARQ design is quantified in terms of end-to-end delay, throughput and SNR gain and in all these metrics, significant performance improvement is observed. Enhanced features, namely, Segmentation and Reassembly (SAR) and Bitmap Compression, are proposed and shown to reduce the overhead costs.

Go-Back-N automatic repeat request (GBN ARQ) and Stop-and wait (SW) ARQ schemes are one of fundamental and widely used error control procedures for data communication and computer communication systems. The throughput and delay performances of these ARQ schemes have been analyzed for a random error channel, which could not applicable for a radio channel, for example. In this paper, considering the correlated, noisy channel, we derive the exact formula for the delay of a frame in GBN and SW ARQ schemes. First, the delay formula for the discrete time M[x]/G/1 queueing system with starter. Next, the virtual service time of a frame is found in terms of the decay factor of a two-state Markov chain. As a result, it is shown that the performance of the delay is improved with the larger decay factor.