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We design and implement a network-coding-enabled reliability architecture for next generation wireless networks. Our network coding (NC) architecture uses a flexible thread-based design, with each encoder-decoder instance applying systematic intra-session random linear network coding as a packet erasure code at the IP layer. Using GENI WiMAX platforms, a series of point-to-point transmission experiments were conducted to compare the performance of the NC architecture to that of the Automatic Repeated reQuest (ARQ) and Hybrid ARQ (HARQ) mechanisms. In our scenarios, the proposed architecture is able to decrease packet loss from around 11-32% to nearly 0%; compared to HARQ and joint HARQ/ARQ mechanisms, the NC architecture offers up to 5.9 times gain in throughput and 5.5 times reduction in end-to-end file transfer delay. By establishing NC as a potential substitute for HARQ/ARQ, our experiments offer important insights into cross-layer designs of next generation wireless networks.

In previous work, MPC(Modified Packet Combining) and PRPC(Packet Reverse Packet Combining) schemes are understood to offer higher throughput and better error correction capability at high bit error rate (BER) and large packet size only. An analysis was performed to corroborate this claim of higher throughput and better error correction capability in high as well as in low bit error rate (BER) for large and medium packet size. To pacification high bit error rate some researchers proposed to use Error Correction Code (ECC) in place of Error Detection Code (EDC) in ARQ scheme. But no incontrovertible result is found to justify the idea in terms of throughput. The recent investigation is an attempt to analyze the throughput. In this paper, we investigate the analysis of both PRPC and MPC in a Modified way over Conventional PRPC, and report the findings available. We propose a combined protocol of Modified PRPC and MPC, and find that it will offer higher throughput and better error correction capability at high and low BER with medium and large packet size as we have used MPC (Modified Packet Combining) scheme with PRPC (Packet Reverse Packet Combining) scheme in a Modified way by combining BEC (Backward Error Correction) with FEC (Forward Error Correction) Codes especially Space-Time Ring-Trellis Coded Modulation (ST-RTCM) code for Communication and Networks by using MATLAB TM software.

This paper propose an adaptive cooperative ARQ mechanism based on the channel station of WiMAX networks, which could obtain high saturation throughput, real-time and reliable transmission at the same time. According to the principle and characteristics of conventional ARQ defined in IEEE 802.16e, a Markov chain model for analyzing the saturation throughput, packet error rate and average delay was built. An adaptive cooperative ARQ mechanism was established based on the Markov chain model. Additionally the above performance of the proposed scheme and the conventional ARQ would also be analyzed and discussed based on such model. The mathematical analysis show that the proposed mechanism could perform better in terms of saturation throughput, reliability and real time performance when compared with the conventional ARQ.

In this paper we present an energy consumption model for a network coding-based cooperative ARQ (Automatic Repeat reQuest) scheme for wireless networks. Applying network coding techniques, we achieve a significant enhancement in the energy efficiency of the network without compromising the Quality of Service in terms of throughput and packet delay. In order to evaluate the proposed solution, we compare our protocol with simple cooperative ARQ protocols, where the retransmissions take place via relays without any network coding capabilities. Finally, both analytical and simulation results are used in order to verify our conclusions.

In this paper, we propose a MIMO approach for packet combining in hybrid automatic repeat request (HARQ) protocols using single-carrier multi-layer transmission over block fading channels. Based on this model, the problem of the optimization of the linear superposition coefficients is briefly addressed.

A hybrid ARQ scheme based on the conception of majority voting for binary linear block codes over AWGN channel is presented. At each transmission, the received word is kept in memory buffers. After a number of receptions, the decoding process first determines each bit as 1 or 0 based on the majority of the corresponding bits in the received words. The word resulting from voting is then decoded by algebraic decoder as the output code word. Simulation results show that the proposed hybrid ARQ scheme outperforms ARQ scheme in both error-correcting performance and throughput efficiency, particularly under low SNR. Additionally, a criterion in measure of throughput and coding gain is proposed for overall evaluation of hybrid ARQ schemes compared to ARQ scheme.

The guaranteed delivery of critical data is an essential requirement in most Wireless Sensor Network (WSN) applications. The paucity of energy, communication, processing and storage resources in each WSN node causes the TCP transport model (widely used in broadband networks) to be inefficient in WSNs, a reason why new WSN-specific reliable transport protocols have been proposed in the past few years. This paper presents one of these protocols, the Distributed Transport for Sensor Networks (DTSN). DTSN is able to efficiently support unicast communications in WSNs due to its capabilities to tightly control the amount of signaling and retransmission overhead. The basic loss recovery algorithm is based on Selective Repeat ARQ, employing both positive and negative acknowledgements. Caching at intermediate nodes is used to avoid the inefficiency typical of the strictly end-to-end transport reliability commonly assumed in broadband networks. DTSN is currently implemented in TinyOS. Preliminary simulation results using this code show that DTSN is quite efficient providing block oriented reliability, while the caching mechanism employed in DTSN decreases packet delay for more than one hop.

Bluetooth provides different kinds of data packet types with different sizes and error correction mechanisms, thus adapter layer can choose the most suitable packet to be transmitted according to the error rate on the link and application requirements. Based on the acknowledgement history of the most recently transmitted packets, an adaptive algorithm is proposed to choose the suitable Bluetooth data packet for transmission through maximizing the expected throughput efficiency of ARQ protocol on Bluetooth ACL data communication link. Simulation results indicate that this method works very well with a short observation history and also show special performance of DM and DH data packet transmission.

In this paper, we present a method to analyze the performance of high-reliability Internet systems in wireless environments with Automatic Repeat ReQuest (ARQ) schemes. Considering the setting up procedure of a data link in wireless networks, we build a Geom/G/1 queue model with a setup strategy to characterize the system operation, and analyze the probability distribution of the system to obtain the performance measures. Numerical results are given to evaluate the performance of different ARQ schemes in terms of the response time and the utility, and to show influence of the delay of the setup procedure and the round-trip-time on the system performance.

We propose a Modulation and Coding Scheme (MCS) selection algorithm for the collaborative hybrid Automatic-Repeat-reQuest (ARQ) protocol in order to provide high data rates. The collaborative hybrid ARQ protocol is designed to benefit from diversity gain. It exploits not only the broadcast nature of wireless channels, but also spatial diversity by formation of virtual antenna arrays and collaboration between a base station and relay nodes through Space-Time Block Coding (STBC). The proposed algorithm estimates both the effective Signal-to-Noise-Ratio (SNR) and the average throughput of each MCS level, and then selects the MCS level maximizing the average throughput. Simulation results show that the proposed algorithm outperforms conventional MCS selection algorithms in terms of the total throughput and satisfies packet delay constraints.

The RFID (Radio-Frequency Identification) system consists of RFID tags and readers for contactless identification. Since RFID tags rely on limited energy, low-power design is very important for the RFID system. Also, the error rates tend to be high, because the link between the reader and the RF tag is wireless and RFID tags and readers could have mobility. To solve these two problems at the same time, we propose a hybrid ARQ (Automatic Repeat Request) scheme with energy efficiency for the RFID system. In our proposed scheme, the BCH channel coding is used together with the optimal packet length in order to minimize the energy consumption. From the results of performance evaluation, the proposed hybrid ARQ scheme can maximize energy efficiency compared to the ARQ scheme or channel coding alone, while satisfying the link reliability.

We propose a Node Cooperative Automatic Repeat reQuest (ARQ) scheme for wireless ad-hoc networks to combat the effects of channel fading on the performance of link layer retransmission scheme. The proposed scheme is inspired by the idea of cooperative diversity. Simulation results are given to demonstrate the significant throughput gain, even when the quality of channel between the communicating nodes is poor.

Link adaptation techniques such as adaptive modulation and coding (AMC) aim at maximizing the throughput in wireless networks. In this paper, we propose new schemes allowing for the combining of AMC at the physical layer with automatic repeat request (ARQ) at the link layer. The method we propose formally maximizes the throughput under delay and packet-loss constraints. In addition, we change the basic paradigm of the AMC and propose to vary the modulation/coding levels depending on the state of the ARQ process. Compared to previous approaches, our results show that the proposed AMC scheme enhances the system’s throughput.

In this paper, we propose a transport layer protocol for oneto-many multicast that is designed to have good scalability properties in large receiver groups and provides reliable transmission. Reliability is achieved using forward error correction (FEC) in combination with selective repeat NAK-based ARQ. Using FEC can significantly reduce the necessity for retransmission requests or make them totally unnecessary, which is important in wireless and satellite communicaton environments, as well as for delay-sensitive multimedia applications. The protocol uses one multicast group address for the original transmission and a second group address for the handling of retransmissions, which helps in significantly reducing the network load on branches with low loss and facilitates usage in the context of satellite communications. We hope that our work will be useful and encouraging for the development of group communication applications.