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The traffic adaptive 2-level active period control has been proposed for performance enhancement in cluster-based wireless sensor networks (WSNs) employing IEEE 802.15.4 medium access control (MAC) under temporal and geographical non-uniform traffic distribution. This paper proposes an adaptive backoff window control method for the traffic adaptive 2-level active period control. The proposed method...
Networks of the future envisage a network-of-wireless-networks that provide the end user the means to connect to the best available network at anytime and at any place. However, equally challenging for the operators is to provide these services at low cost in an era where spectral resources are a premium. This paper investigates cooperation between networks based radio access technology (RAT) selection...
The automation architecture consists of actuators, sensors, programmable logic controllers (PLC) and monitoring systems. Some research focuses on how to replace the communication between those entities from wired to wireless communication taking in consideration the industrial constraints, given the advantages of this kind of communication. To study the performance of the wireless network system,...
DQCA is a near-optimum medium access control (MAC) protocol designed for wireless local access networks (WLANs). The protocol operates as a random access scheme under low traffic load and switches smoothly and automatically to a reservation scheme as the traffic grows. The inherent feedback mechanism of DQCA facilitates the implementation of a link adaptation algorithm that properly selects the best...
Wireless sensor networking is an emerging technology that has a wide range of potential applications. In this paper an efficient hybrid MAC layer protocol has been proposed, utilized ZigBee MAC (EZ-MAC), for sensor networks. Sensor networks have to manage variety of traffics such as real-time traffics and sensor traffics. Since most of real-time traffics are time-restricted, service access delay is...
Proportional fair (PF) scheduling algorithm selects a user according to the ratio between the user current channel rate and the user average channel rate, which provides a good performance in terms of fairness. However, PF scheduler can not guarantee a quality of service (QoS) requirement be achieved. Moreover, if a variable bit rate (VBR) traffic is considered under different channel conditions for...
IEEE P1900.4 is an emerging standard for optimized radio resource utilization where cognitive radio technologies are used for efficient spectrum utilization. In this paper, we design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluate its performance using UDP streaming and HTTP download. Our experiments show interesting results that total network...
The multi-access scheme of 802.11 wireless networks imposes difficulties in achieving predictable service quality in multi-hop networks. In such networks, the residual capacity of wireless links should be estimated for resource allocation services such as flow admission control. In this paper, we propose an accurate and non-intrusive method to estimate the residual bandwidth of an 802.11 link. Inputs...
In this paper we focus on the control of wireless transmissions in a CDMA cell with users generating random traffic. The quality of service perceived by a user is a function of the average packet delay including the coding process and the retransmission phase. The packet retransmission probability depends on the quality level of the channel which is a function of the signal to interference noise ratio...
In this paper, we study bandwidth management of a wireless/optical based access/metro network in support of voice and data services. For voice services, we use a finite state Markov Chain to estimate the blocking probability of voice circuits over an Adaptive modulation and coding wireless channel, as a function of the channel parameters. For data services, we evaluate a rate matching and a buffer...
In this paper, we address the issue of transmission power control (TPC) in wireless ad hoc networks. Power control plays an important role in energy saving and network performance enhancement. However, the existing TPC schemes either face the problem of hidden and exposed terminal or have additional hardware requirements. We propose a novel distributed power control protocol, called Receiver Initiated...
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