Relay selection in mobile multihop relay network

Mobile Multihop Relay (MMR) network is an attractive and low-cost solution for expanding service coverage and enhancing throughput of the conventional single hop network. However, mobility of Mobile Station (MS) in MMR network might lead to performance degradation in terms of Quality of Service (QoS). Selecting an appropriate Relay Station (RS) that can support data transmission for high mobility MS to enhance QoS is one of the challenges in MMR network. The main goal of the work is to develop and enhance relay selection mechanisms that can assure continuous connectivity while ensuring QoS in MMR network using NCTUns simulation tools. The approach is to develop and enhance relay selection that allows cooperative data transmission in transparent relay that guarantees continuous connectivity. The proposed relay selection defined as Co-ReSL depends on weightage of SNR, α and weightage of Link Expiration Time (LET), β. The QoS performances of the proposed relay selections are in terms of throughput and average end-to-end (ETE) delay. The findings for Co-ReSL shows that at heavy traffic load, throughput increases up to 5.7% and average ETE delay reduces by 7.5% compared to Movement Aware Greedy Forwarding (MAGF) due to cooperative data transmission in selective links. The proposed relay selection mechanisms can be applied in any high mobility multi-tier cellular network

Irregular repetition code hybrid ARQ in wireless system

Error control consists of error detection and error correction in the communication system. The purpose of this research work is to reduce error in the wireless communication system by using the advantages of both error correction techniques which are forward error correction (FEC) and automatic repeat request (ARQ). Thus, error can be corrected without retransmission and also via retransmission(s) when needed. Combination of FEC and ARQ is known as Hybrid ARQ. In this paper, Hybrid ARQ system is designed using three components which are the irregular repetition code (IRC) as a simple code, bit-interleaved coded modulation with iterative decoding (BICM-ID) as a simple Turbo processing and ARQ. The HARQ system is enhanced by the extended mapping (EM) adopted in the mapping system. The performance of the systems is evaluated in the additive white Gaussian noise (AWGN). The results show the Hybrid ARQ with extended mapping (Hybrid ARQ-EM) outperforms Hybrid ARQ with standard mapping (Hybrid ARQ-SM). Hybrid ARQ-EM achieves low bit error rate BER (10-5) at low signal-to-noise ratio SNR which only 3.03dB close to the theoretical limit. The proposed system Hybrid ARQ-EM achieves 52 percent gain enhancement of SNR gap from the theoretical limit compared to Hybrid ARQ-SM. Hybrid ARQ-EM gives better performance although in worse channel condition

MPEG-4 video transmission using distributed TDMA MAC protocol over IEEE 802.15.4 wireless technology

The issues of green technology nowadays give an inspiration to the researcher to make all the future design to be energy efficient. Medium Access Control (MAC) layer is the most effective layer to provide energy efficient due to its ability to control the physical radio directly. One of the important applications in the future is a video transmission that can be transmitted with low-cost and low power consumption. MPEG-4 is one of the international standards for moving video. MPEG-4 provide better compression and primarily design at low bit rate communication. In order to achieve good quality for video application, the design at MAC layer must be strong. Therefore, to increase the performance of the MPEG-4 in IEEE 802.15.4, in this paper we propose a cross layer design between MAC layer and Application layer. A priority queue will be implemented at MAC scheduling depends on the level of frame important in MPEG-4 format frame. A distributed Time division Multiple Access (TDMA) will be used for MAC protocol to provide reliable data transmission for high priority frame

Adaptive FEC error control scheme for wireless video transmission

Transmission errors have detrimental impact on video quality in wireless network. Hence, this requires highly efficient error correction scheme to significantly improve the quality of the media content. Deploying error correction technique alone would not strategically eradicate the problem unless some adaptation mechanism has been included in order to make efficient decision while adding more redundant information base on the channel condition. Adapting with channel condition can significantly enhance the network performance and video quality as well. In this paper, we paper presents an approach using forward error correction and cross layer mechanism which dynamically adapts with the channel condition to recover the loss packets in order to enhance the perceived video quality. The scheme has been developed and tested on NS-2 simulator and it shows more dramatic improvement in video quality

Hop aware scheduling algorithm for TCP performance enhancement in multi hop relay wimax

Mobile Multi-hop Relay (MMR) WiMAX networks allow the number of hops between the user and the MMR-BS to be more than two hops when the non transparent relay station is used. Transmission Control Protocol (TCP) protocol is optimized to be used in wired networks where the main cause of loss is the congestion. TCP throughput is highly affected by packet losses or timeout occurrences because of its congestion control mechanism. Upon the occurrence of timeout, TCP decreases the transmission window which results in throughput degradation, even if such losses are not due to congestion. This paper presents link layer scheduling algorithm to enhance the TCP in IEEE 802.16j MMR WiMAX networks. The aim is to reduce the Retransmission Timeout (RTO) occurrences and enhance the throughput. The results showed that the hop aware scheduling algorithm gives higher throughput, and less timeout occurrence for different BER values

Data recovery in wireless sensor networks using network coding

Data transportation over resources constraint and noisy channel of wireless sensor network (WSN) is very challenging in term of guaranteeing the data survival along the transmission. However, with the convergence of different research areas such as routing, source and channel coding techniques, the WSN technology has successfully been tremendously developed. This paper proposes an on-the-fly data recovery (ODR) scheme using network coding in order to enhance the robustness of the network against packet loss. Along with the ODR scheme, the packet loss formulation is presented while a network model for a network coding designed is also introduced namely for erasure channel. The data generated by the sources are transferred to the destination through relay nodes via three transmission paths. In ODR process, the lost packet is recovered by a relay node by listening to the transmission of two adjacent nodes and performing the XOR operation on the listened packets. We provide the analytical study on network coding performance and conducting the simulation experiment to verify it. In the simulation studies, we have also compared the performance of the network using network coding with and without packet recovery. The result shows that the number of packet loss has been reduced significantly using the proposed scheme compared to the network with normal network coding

M2M Communication in Virtual Sensor Network for SHAAL

Machine-to-Machine (M2M) communication has led to a new paradigm of Internet of Things (IoT). The future of M2M communication in smart home lies in the aggregation and allocation of resources and service provisioning of diverse applications using different radio technologies. M2M communication may operate on the virtual sensor network to provide independent applications running on heterogeneous network simultaneously. M2M is going to play a major role in the area of Smart Home and Ambient Assisted Living (SHAAL) providing assistance to the elderly people with smart sensors that monitor the home environment and provides aid health monitoring to human requiring medical assistance. The current state of the art frameworks are dedicated to specific applications with the support of single radio network with limited service provisioning options. However, in order to fully exploit the resources in this paper we present a service provisioning framework realization of M2M in virtual sensor network for SHAAL, which allows independent parties to work together in a secure and reliable manner. In addition to this, the framework is designed to include benefits of Service Oriented Architecture (SOA) and Resource Oriented Architecture (ROA) along with the use of different low power, low data rate protocols. A middleware is used as a platform to link the underlying virtual networks with various applications. The network virtualization approach is adopted to design an efficient middleware framework that can effectively discover and manage the underlying network resources and provide services at home gateway. The framework will be used as the basis for the development of the SHAAL networked system

Multi Hop Transmission in IEEE 802.11 Low Rate Ad Hoc Network Using ARP-Route

Ad hoc networks are becoming more important in the modern complex environment. The ad hoc network can be used to instantly connect to the local or remote networks such as the Internet without the need of pre-existing infrastructure or centralized administration. The users of the network together will establish the infrastructure. The disadvantage of wireless communication is that it has limited range of radio transmission. Due to this, multiple network ‘hops’ are needed for one device to exchange data with another deviceacross the network. In an ad hoc network, these devices will not only operate as a host but also as a router to forward the packets. There are varieties of routing protocols targeted for this environment that have been proposed and developed. However, most of them suffer from high overhead data traffic. The main purpose of this project is to implement the ad hoc network with the existing network protocol that had already been used in network environment which is the Address Resolution Protocol (ARP). ARPwas designed to announce or find MAC addresses. The novelty ofthis study is that we have extended the usage of the ARP protocol to act as routing protocol in wireless ad hoc network. The ARP route provides two new operation types, ARP Forward Request and ARP Forward Reply to allow the multihop transmission using intermediate nodes to forward the request and reply. These two operation types only used the current operation codes which are ‘0x0001’ for request and ‘0x0002’ for reply. This work onthe routing protocol creates a new operation code for the ARP forwarding scheme which is ‘0x000c’ for forwarding. We have successfully managed to create a multi hop transmission in anad hoc network by using the current existing operation code for the ARP forwarding. The work scope focus only on proving that the method can be applied hence it is not necessarily to prove the effectiveness of this proposed method yet. Therefore,the outcome of the study shows that the data can be sent through multi hop transmission until it reaches the destination. The 802.11btest-bed has been configured and the ARP routing protocol has been implemented for multi hop transmission. The experiment in the open space provides the comparison of environment with obstacles and without obstacles. We manage to get more than 50% of packet receive at a place with no obstacles and more than 45% in a place with obstacles. The proof of method is shown by using several graphs namely in terms of time, packet loss and also throughput

Implementation of geocast-enhanced AODV-bis routing protocol in MANET

Mobile ad hoc network (MANET) represents a complex distributed system that enables seamless internetwork in areas with no pre-existing communications infrastructure. Far less effort has been done on the real-world basis, with intensive evaluations through simulations. This paper outlines our experiences with the implementation of MANET testbed based on geocast-enhanced AODV-bis module. AODV-bis is an improved design of MANET routing protocol, from the lessons learned beyond the experimental RFC AODV effort. The main goal of our research is to develop and verify the practicality of AODV-bis (ad-hoc on-demand distance vector-bis) routing protocol, featuring path accumulation. To enhance AODV-bis, location information is utilized during route discovery to limit forwarding zone by geocasting. It can be done with only little modification of packet format. We found that AODV-bis, compared to AODV, is a more powerful routing protocol especially in disseminating route information. Its overall performance is further improved with the aid of geocasting

PAPR reduction in WLAN-OFDM system using code repetition technique

Orthogonal frequency division multiplexing (OFDM) is the best choice to achieve high data rate transmission in wireless environment. OFDM system shows many favorable property such as high spectral efficiency, robustness to channel fading and immunity to impulse interference. However, there are some obstacles in using OFDM in transmission system, which is in contrast to its advantages. One of the major drawbacks is a very high peak to average power ratio (PAPR) of the OFDM signals. Therefore this paper analyzes the capability of code repetition (CR) to reduce PAPR in WLAN/OFDM system. The analysis is on a network model designed by WLAN 802.11a standard using Matlab, a mathematical simulation software tool. The network model has been simulated in AWGN channel environment to investigate the behavior of PAPR and BER performance. The proposed technique to reduce PAPR in the WLAN/OFDM channel coding consists of two part; convolutional code and CR. Simulation model with different number of repetition has been analyzed and the results were compared with the conventional coded OFDM (COFDM). The simulation results show that the proposed technique based on CR reduces PAPR down to 5 dB compared to COFDM model