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An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administration. A number of routing protocols such as Dynamic Source Routing (DSR), Ad Hoc on-Demand Distance Vector Routing (AODV) and Destination-Sequenced Distance-Vector (DSDV) have been implemented. In this paper, an attempt has...
Various transmission control protocol (TCP) enhancement schemes have been proposed to improve TCP performance over mixed wired/wireless networks. Among the different kinds of TCP enhancement schemes, end-to-end TCP enhancement schemes have the lowest implementation complexity and do not violate the semantics of TCP. Their general principle is to distinguish wireless loss from congestion loss, and...
We analyze TCP-controlled bulk file transfers in a single station WLAN with nonzero propagation delay between the file server and the WLAN. Our approach is to model the flow of packets as a closed queueing network (BCMP network) with 3 service centres, one each for the Access Point and the STA, and the third for the propagation delay. The service rates of the first two are obtained by analyzing the...
This paper addresses a H∞ TCP controller for end-to-end TCP congestion control. The proposed controller which is based on the algorithm of TCP Vegas is aimed to minimize error term in TCP Vegas and achieve one step optimal solution for TCP congestion control. A series of simulation experiments based on a single bottle-neck FIFO queue model are conducted to compare the new controller with TCP Vegas...
Reliability and timeliness are two essential requirements of successful detection of critical events in Wireless Sensor Networks (WSNs). The base station (BS) is particularly interested about reliable and timely collection of data sent by the nodes close to the ongoing event, and at that time, the data sent by other nodes have little importance. In this paper, we propose Congestion and Delay Aware...
We propose an approach for opportunistic forwarding that supports optimization of multipoint high volume data flow transfer while maintaining high buffer availability and low delays. This paper explores a number of social, buffer and delay heuristics to offload the traffic from congested parts of the network and spread it over less congested parts of the network in order to keep low delays, high success...
In wide-area video conferencing, the rate control of video sources to relieve network congestion along the multicast data path occurs in a distributed manner. In this paper, we study the desirable properties of signaling channels that carry the `packet loss report' (ELR) from a receiver to the sources as a short control message. A signaling channel provides for loss-free and time-ordered flow of ELRs...
In this paper, we propose a QoS control mechanism that estimates the congestion of wireless channels in the wireless LAN and evaluates the voice packet drop ratio based on the estimated congestion status. The mechanism adjusts the voice packet transmission rate according to the evaluated packet loss ratio, and thereby resolves the congestion situation. In this way, the mechanism can keep users' quality...
The performance of TCP-based applications depends on the selection of queue management mechanism in network routers and how well its control decisions are made. Fast Congestion Notification (FN) mechanism enables the two control decisions, packet admissions and congestion control directing, to be made together. This permits sending congestion avoidance notification as early as required, even if the...
Stringent QoS maintenance in a wireless environment for VoIP communication is a major challenge. VoIP inherently generates constant bit rate traffic and is highly sensitive to network delay. However, unpredictable network congestion makes a VoIP session so degraded that its QoS goes below a tolerable limit. Accordingly, a suitable solution is needed to adapt varying network conditions satisfying minimum...
Multi-channel multi-radio wireless networks improve network performance by enabling more simultaneous transmissions. Among multi-channel multi-radio protocols, the hybrid multi-channel approach has been shown to be efficient in providing higher system throughput. Voice over internet protocol (VoIP) service is expected to be widely supported in wireless networks, though its capacity has not been studied...
In this paper, we propose a distributed call admission control scheme for multiservice OFDMA system. In our proposed call admission control (CAC) scheme, a cell dynamically adjusts optimal new call and handoff acceptance ratios by three steps. First, exchange numbers of calls in handoff area with its adjacent cells. Then, dynamically allocate resource for different types of traffic. Finally, use a...
Although the IEEE 802.16 standard defines various QoS classes and their associated parameters, it does not define the scheduling, routing, and Call Admission Control (CAC) algorithms to be used in the network. It is left unstandardized for vendor differentiation. Currently, scalable distributed scheduling and routing algorithms are available for IEEE 802.16 mesh networks. But, the existing CAC algorithms...
Delivering desired QoS to the applications is one of the most important challenges in next generation networks. Designing efficient queue management in midway nodes leads to improvement in NGN efficiency. This paper presents fair Efficient active Queue Management (EQM) mechanism for congestion avoidance and control in next generation networks. Proposed AQM mechanism uses instantaneous queue length...
Ad hoc networks are useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable, and movement of communicating parties are allowed. Due to the dynamic topology, developing better routing protocol became a challenging task. The Dynamic Source Routing (DSR) protocol is a simple and efficient routing protocol...
We propose a concurrent collision avoidance scheme based on wavelength rotation (WR) in optical WDM networks. By introducing wavelength cost during the path computation process, the proposed scheme can significantly reduce the concurrent blocking probability (BP), without introducing additional connection setup delay compared with the time-threshold-based concurrent RWA schemes.
In the present heterogeneous wired networks, reliability priority consideration is important. Quality of Service (QoS) varies according to congestion in the network and it can be avoided by different TCP Agents using congestion control algorithms. Previously, researches had only analyzed TCP agents, we extend their work to practical simulation for the multisource scenario to compare performance evaluation...
Traffic management and adjustment is obviously of great importance in any communication network. Without traffic supervision and control, an increase in demand for network resources can lead to a significant decrease in network service quality and efficiency. Since the most important issue in the field of control theory is stability of dynamic systems, control science can be appropriately applied...
The performance of wireless LANs is greatly affected by path loss, RF interference and other sources of signal attenuation in addition to network congestion. The primary factors involved in effective real-time communication, namely delay and loss, must be within certain controlled limits in such a scenario. In this paper, we analyze the various factors driving IEEE 802.11b access points through extensive...
Tag Collisions in RFID systems is a prime issue which causes identification delay and data loss. This paper presents an efficient algorithm called Least and Most significant Bit Arbitration (LaMSBA) to reduce idle and collision slots. The algorithm makes the reader to take full advantage when ever a collision occurs by constructing a partial tree for multiple tags, which in turn prevents redundancy...
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