The application of forward error correction techniques in wireless ATM

Bibliography: pages 116-121.The possibility of providing wireless access to an ATM network promises nomadic users a communication tool of unparalleled power and flexibility. Unfortunately, the physical realization of a wireless A TM system is fraught with technical difficulties, not the least of which is the problem of supporting a traditional ATM protocol over a non-benign wireless link. The objective of this thesis, titled "The Application of Forward Error Correction Techniques in Wireless ATM' is to examine the feasibility of using forward error correction techniques to improve the perceived channel characteristics to the extent that the channel becomes transparent to the higher layers and allows the use of an unmodified A TM protocol over the channel. In the course of the investigation that this dissertation describes, three possible error control strategies were suggested for implementation in a generic wireless channel. These schemes used a combination of forward error correction coding schemes, automatic repeat request schemes and interleavers to combat the impact of bit errors on the performance of the link. The following error control strategies were considered : 1. A stand alone fixed rate Reed-Solomon encoder/decoder with automatic repeat request. 2. A concatenated Reed-Solomon, convolution encoder/decoder with automatic request and convolution interleaving for the convolution codec. 3. A dynamic rate encoder/decoder using either a concatenated Reed-Solomon, convolution scheme or a Reed-Solomon only scheme with variable length Reed-Solomon words

A proxy for reliable 5G (and beyond) mmWave communications. Contributions to multi-path scheduling for a reliability focused mmWave proxy

Reliable, consistent and very high data rate mobile communication will become especially important for future services such as, among other things, future emergency communication needs. MmWave technology provides the needed capacity, however, lacks the reliability due to the abrupt capacity changes any one path experiences. Intelligently making use of varying numbers of available mmWave paths, efficiently scheduling data across the paths, perhaps even through multi-operator agreements; and balancing mobile power consumption with path costs and the need for reliable consistent quality will be critical to attaining this aim. In this thesis, the multipath scheduling problem in a mmWave proxy when the paths have dynamically changing path characteristics is considered. To address this problem, a hybrid scheduler is proposed, the performance of which is compared with the Round Robin scheduler, Random scheduler and the Highest Capacity First scheduler. Forward error correction is explored as a means of enhancing the scheduling. Keywords:Multipath Scheduling, mmWave Proxy, Forward Error Correction, beyond 5G

Optimising lower layers of the protocol stack to improve communication performance in a wireless temperature sensor network

The function of wireless sensor networks is to monitor events or gather information and report the information to a sink node, a central location or a base station. It is a requirement that the information is transmitted through the network efficiently. Wireless communication is the main activity that consumes energy in wireless sensor networks through idle listening, overhearing, interference and collision. It becomes essential to limit energy usage while maintaining communication between the sensor nodes and the sink node as the nodes die after the battery has been exhausted. Thus, conserving energy in a wireless sensor network is of utmost importance. Numerous methods to decrease energy expenditure and extend the lifetime of the network have been proposed. Researchers have devised methods to efficiently utilise the limited energy available for wireless sensor networks by optimising the design parameters and protocols. Cross-layer optimisation is an approach that has been employed to improve wireless communication. The essence of cross-layer scheme is to optimise the exchange and control of data between two or more layers to improve efficiency. The number of transmissions is therefore a vital element in evaluating overall energy usage. In this dissertation, a Markov Chain model was employed to analyse the tuning of two layers of the protocol stack, namely the Physical Layer (PHY) and Media Access Control layer (MAC), to find possible energy gains. The study was conducted utilising the IEEE 802.11 channel, SensorMAC (SMAC) and Slotted-Aloha (S-Aloha) medium access protocols in a star topology Wireless Temperature Sensor Network (WTSN). The research explored the prospective energy gains that could be realised through optimizing the Forward Error Correction (FEC) rate. Different Reed Solomon codes were analysed to explore the effect of protocol tuning on energy efficiency, namely transmission power, modulation method, and channel access. The case where no FEC code was used and analysed as the control condition. A MATLAB simulation model was used to identify the statistics of collisions, overall packets transmitted, as well as the total number of slots used during the transmission phase. The bit error probability results computed analytically were utilised in the simulation model to measure the probability of successful transmitting data in the physical layer. The analytical values and the simulation results were compared to corroborate the correctness of the models. The results indicate that energy gains can be accomplished by the suggested layer tuning approach.Electrical and Mining EngineeringM. Tech. (Electrical Engineering

Network Coding for Multihop Wireless Networks: Joint Random Linear Network Coding and Forward Error Correction with Interleaving for Multihop Wireless Networks

Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment.Indonesian Government and the University of Bradfor

Evaluating and improving the performance of video content distribution in lossy networks

The contributions in this research are split in to three distinct, but related, areas. The focus of the work is based on improving the efficiency of video content distribution in the networks that are liable to packet loss, such as the Internet. Initially, the benefits and limitations of content distribution using Forward Error Correction (FEC) in conjunction with the Transmission Control Protocol (TCP) is presented. Since added FEC can be used to reduce the number of retransmissions, the requirement for TCP to deal with any losses is greatly reduced. When real-time applications are needed, delay must be kept to a minimum, and retransmissions not desirable. A balance, therefore, between additional bandwidth and delays due to retransmissions must be struck. This is followed by the proposal of a hybrid transport, specifically for H.264 encoded video, as a compromise between the delay-prone TCP and the loss-prone UDP. It is argued that the playback quality at the receiver often need not be 100% perfect, providing a certain level is assured. Reliable TCP is used to transmit and guarantee delivery of the most important packets. The delay associated with the proposal is measured, and the potential for use as an alternative to the conventional methods of transporting video by either TCP or UDP alone is demonstrated. Finally, a new objective measurement is investigated for assessing the playback quality of video transported using TCP. A new metric is defined to characterise the quality of playback in terms of its continuity. Using packet traces generated from real TCP connections in a lossy environment, simulating the playback of a video is possible, whilst monitoring buffer behaviour to calculate pause intensity values. Subjective tests are conducted to verify the effectiveness of the metric introduced and show that the results of objective and subjective scores made are closely correlated

Ber Performance Evaluation Of Ofdm System Using Ldpc-Rs And Ldpc-Cc Product Codes

Error control coding techniques is a crucial part of digital communication systems. It is used to solve the errors created by the noise channel during data transmission of digital communication systems. LDPC codes have been shown to offer significant performance gain close to the fundamental limits of channels corrupted by an additive random noise. This thesis particularly investigates the performance of LDPC codes with concatenated Reed-Solomon code (LDPC-RS) and convolutional codes (LDPC-CC) for possible bit-error-rate (BER) performance gain over the Orthogonal Frequency Division Multiplexing (OFDM) system that experiences multipath fading. A channel estimation model for the OFDM system is developed. The OFDM system has an IFFT size of 64. Subsequently, the BER of the signal in OFDM system is examined using Forward Error Correcting (FEC) code namely Convolutional code, Reed-Solomon code, LDPC, LDPC-RS and LDPC-CC. Convolutional code and Reed-Solomon code are implemented using three different code rates which are 1/2, 1/3 and 2/3. The best FEC code with the best BER performance is determined by analysing the SNR versus BER graph. LDPC-CC and LDPC-RS has a performance gain of 6 dB and 5 dB respectively, compared to LDPC at BER of 10−1. It is concluded that concatenated codes (LDPC-CC and LDPC-RS) have better BER performance

ENSURE: A Time Sensitive Transport Protocol to Achieve Reliability Over Wireless in Petrochemical Plants

As society becomes more reliant on the resources extracted in petroleum refinement the production demand for petrochemical plants increases. A key element is producing efficiently while maintaining safety through constant monitoring of equipment feedback. Currently, temperature and flow sensors are deployed at various points of production and 10/100 Ethernet cable is installed to connect them to a master control unit. This comes at a great monetary cost, not only at the time of implementation but also when repairs are required. The capability to provide plant wide wireless networks would both decrease investment cost and downtime needed for repairs. However, the current state of wireless networks does not provide any guarantee of reliability, which is critical to the industry. When factoring in the need for real-time information, network reliability further decreases. This work presents the design and development of a series of transport layer protocols (coined ENSURE) to provide time-sensitive reliability. More specifically three versions were developed to meet specific needs of the data being sent. ENSURE 1.0 addresses reliability, 2.0 enforces a time limit and the final version, 3.0, provides a balance of the two. A network engineer can set each specific area of the plant to use a different version of ENSURE based network performance needs for the data it produces. The end result being a plant wide wireless network that performs in a timely and reliable fashion

Integration of optical communications in an underwater docking station

As problems within underwater communication arise, there is a need to transfer data at high rates. For this reason, optical communication is deployed for underwater systems.This thesis proposes an optical communication protocol between an underwater station and an AUV, designed to ensure reliable communication while maintaining high speeds of transmission