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In this paper, we propose a new QAPM scheme for improving power efficiency. A proposed QAPM scheme is build on QAM. And BER performance of QAPM is better than existing PSSK because BER performance of QAM is better than PSK. In this paper, we find the BER performance closed form of QAPM modulation. Also, we compare to PSSK and QAPM with regard to BER performance and throughput in AWGN channel.
Aggressive scaling of transistors allows integration of hundreds of processors on a chip. However, on-chip interconnects carrying signals between different blocks will be the bottleneck for system performance and reliability. To tackle this problem, we developed an on-chip communication infrastructure based on a network-on-chip architecture and developed a hybrid mechanism to transfer data among IP...
We study the performance of cognitive (secondary) users in a cognitive radio network which uses a channel whenever the primary users are not using the channel. The usage of the channel by the primary users is modelled by an ON-OFF renewal process. The cognitive users may be transmitting data using TCP connections and voice traffic. The voice traffic is given priority over the data traffic. We theoretically...
This paper investigates the implications of topologies on the average path length of networks, which is the dominant parameter affecting performance. Based on the available literature, classic network topologies are reviewed and analyzed. Furthermore, a new class of communication networks is introduced, and a topology design algorithm is proposed to improve network performance in terms of average...
To reduce the channel access latency in WiMedia networks, we propose a distributed and dynamic adaptation scheme (DDAS) where the optimal transmission probability contention window size is derived after getting traffic information by means of distributed beaconing procedures. Simulation results demonstrate that DDAS can reduce the channel access latency significantly, especially when the number of...
The use of multiple radios tuned to non-overlapped channels, can increase the throughput of a wireless network. However, equipping a node with multiple radios can cause a proximity problem between antennas. In this context, the leakage power generated from co-located antennas, which is known as inter-radio interference (or inter-antenna interference), causes throughput degradation. In order to prevent...
In a wireless domain where a mobile user accesses heterogeneous wireless technologies with multiple interfaces, a multi-path scheduling algorithm can benefit mobile users' experience by aggregating different network bandwidth together. However, existing literature actually shows that for TCP flows, it may not be the case. To better exploit multi-path scheduling for TCP connections, this paper presents...
This paper takes into account the uncertainty of the primary users' locations and transmission power in designing an optimal downlink scheduling scheme for cognitive radio cellular networks (CogCells). Localization technique is exploited to estimate the position and transmission power of the primary user (PU) transmitting on specific channel. The objective of our scheduling scheme is to maximize the...
In heterogeneous wireless network environment, various radio access networks (RANs) are available for mobile terminals which have multiple wireless network interfaces to connect to each different RAN. However, it is very difficult to improve the throughput by aggregating different RANs, which have different quality of service (QoS) in the throughput, the delay, the packet loss, and so on. In this...
In the pioneering works, network coding has shown great potential to improve the performance of wireless networks. However, most of them are implemented under specific traffic pattern. Since various traffic patterns will affect the promising gains of network coding, in this paper, we study how traffic pattern affects the benefits of general practical network coding scheme-Multi-hop Network Coding...
Although more than a decade of research has been done but pure general-purpose MANET is still not available rather than few prototypes within laboratory due to both technical and socio-economic point of view. Lacking in appropriate guidelines for realistic user traces, mobility models, routing protocols and considering real-life challenges, it is difficult to reproduce any typical scenario in reality...
We analyze the characteristics and performance of a wireless ad hoc network where nodes are connected via random channels and information is transported in the network in a cooperative multihop fashion using amplify and forward relay strategy. We characterize the network by studying important parameters such as: (1) SNR degradation with hop, (2) outage probability, (3) maximum permissible number of...
The batch resolution problem consists in arbitrating the channel access of a group of nodes in a wireless network in order to collect a single packet from each node in the shortest time. Most of existing solutions are based on the immediate feedback assumption and typically neglect or underestimate the actual time cost of feedback that can instead be significant in common wireless standards. In this...
Packet level coding schemes are used to improve the transmission reliability and efficiency in data broadcasting applications, especially for wireless networks. However, existing coding schemes have large redundancy for packets are coded by a random way or some certain probability distributions. Although the Maximum Distance Separable (MDS) codes are designed without redundancy, they are not effective...
Traditional scheduling algorithms are focused in maximizing system throughput considering a grade of fairness. However, maximizing the system throughput does not necessarily result in maximizing the number of satisfied users (users with a packet delay below a threshold). More over, the throughput maximization could cause a low grade of fairness. In this paper, we propose a low complexity scheduling...
In this paper, we study the multi-channel exposed terminal problem in multi-hop wireless networks. We first explain how the multi-channel exposed terminal problem occurs. We then propose a multi-channel MAC protocol, called multi-channel MAC with hopping reservation (MMAC-HR), to resolve the multi-channel exposed terminal problem. The proposed MMAC-HR protocol has the following features: 1) it does...
This paper investigates the performance effects of packet depletion on multihop wireless networks. The resulting capacity usage inefficiencies of link assigned schedules are shown even at the maximum supportable uniform network load. Hybrid node-link assignment is employed to extend transmission rights, allowing nodes to transmit on sets of reserve links when the primary scheduled link experiences...
Significant progress has been made in the past few years on Dynamic Spectrum Access (DSA) wireless networks which seek to use RF spectrum more efficiently and dynamically. For example, many measurements of current spectrum utilization are available and theoretical analyses and computational simulations of DSA networks abound. In sharp contrast, few network systems, particularly those with a decentralized...
Traditional contention-based random-access wireless MAC protocols such as IEEE 802.11 DCF are designed for single-hop wireless networks and do not perform well in multi-hop scenarios due to inefficiency in their medium reservation mechanisms. In this paper, we introduce a new MAC protocol, called EMAC, which improves the efficiency of wireless medium reservation for general asynchronous multi-hop...
With the development of novel access technologies e.g. LTE, WiMAX etc., the mobile devices are able to establish services over multiple wireless connections with different momentary capabilities. Being imported from the fixed line communication, the current services deployed are lacking an efficient mechanism of adaptation to the momentary connectivity conditions, which deters the efficiency of the...
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