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Orthogonal Frequency Division Multiplexing (OFDM) and multiple antennas are being used in various standards of Wireless Local Area Network (WLAN) to enhance data rates and to achieve higher reliability in fading channel conditions. Channel modeling plays a crucial role, especially in wireless environment, in evaluating the performance of physical layer in fading environment. The paper presents a Finite...
The Performance of IEEE 802.11 distributed coordination function (DCF), under ideal channel conditions degrades mainly due to packet collisions at MAC layer. However, studies reveal that MAC layer performance significantly reduces when wireless networks encounter channel fading at physical layer. Since fading results in burst errors, in addition to errors caused by collisions at MAC layer. In this...
Turbo Convolutional Codes (TCC) are excellent error correcting codes. However, TCC decoders require large number of computations. Recently, a class of low complexity modified Turbo codes termed as Low Complexity Hybrid Turbo Codes (LCHTC) and Improved Low Complexity Hybrid Turbo Codes (ILCHTC) have been proposed. Simulation results show that the proposed codes achieve performance close to that of...
Turbo convolutional codes (TCC) are excellent error correcting codes as they show near Shannon capacity performance in communication systems. However, turbo decoders are computationally complex. Recently, a class of modified turbo codes called low complexity hybrid turbo codes (LCHTC) is proposed with bit error rate (BER) which is almost same as that of turbo codes. In this paper improved low complexity...
As wireless local area networks (WLAN) become ubiquitous and an integral part of data networks, they will also be increasingly used for applications ranging from standard Internet services like ftp to time bound multimedia applications, such as Voice (or Video) over IP (VoIP/VIP), HDTV etc. with strict latency, throughput or jitter restrictions. These applications on WLAN will also be more bandwidth...
Mobile ad hoc networks are networks without fixed infrastructure. The mobile nodes perform both as a host and as a router by forwarding packets to other nodes. Because of the nature of ad hoc networks, there are special demands for ad hoc routing protocols and the performance of these routing protocols is an important issue. This paper presents a simulation based comparative performance analysis of...
Efficient and improved methods of secured route discovery and secured data transmission in Mobile Ad-hoc Networks (MANET) are most recent research issues for ensuring full applicability of deploying MANETs in wide range of applications, including strategic as well as non-strategic. Secured route discovery has been addressed by SRP/SMT, as a generic protocol independent technique for secured route...
Wireless local area nerworks (WLANs) are increasingly finding applications that include real time traffic like voice over IP (VoIP). Medium access coordination function for WLANs in IEEE 802.11 basically implements medium access control (MAC) by employing distributed coordination function (DCF). IEEE 802.11 WLANs provide limited support for quality of service (QoS). A new standard, namely IEEE 802...
Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. Simulation models are often used to estimate channel behavior due to higher complexity...
Original turbo codes are series or parallel combination of component codes (C. Berrou and A. Glavieure, 1996) (W. Graham, 2004). We present a new multiple concatenated turbo code construction comprising both series and parallel concatenations. Proper partitioning of message bits and the use of double binary rate 2/3 convolutional code reduces the complexity of decoder further. Simulation results demonstrate...
On-demand routing protocols for Mobile Ad-hoc Networks (MANET) include Dynamic Source Routing (DSR), which is capable of discovering multiple routes. Secured Routing Protocol (SRP) on the other hand provides mechanism for secured route discovery, even under adversarial conditions. The paper proposes integration of SRP features in DSR to gain security features for MANET routing requirements for the...
This research work address the fundamental issue of providing the desired quality of service (QoS) to the users of ABR service class in ATM networks by providing efficient flow control and congestion control scheme. A centralized flow control scheme (CFCS) is proposed which is simple to implement and has several added features than other flow control schemes reported in the literature. It is robust,...
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