Performance of TCP/UDP under Ad Hoc IEEE802.11

TCP is the De facto standard for connection oriented transport layer protocol, while UDP is the De facto standard for transport layer protocol, which is used with real time traffic for audio and video. Although there have been many attempts to measure and analyze the performance of the TCP protocol in wireless networks, very few research was done on the UDP or the interaction between TCP and UDP traffic over the wireless link. In this paper, we tudy the performance of TCP and UDP over IEEE802.11 ad hoc network. We used two topologies, a string and a mesh topology. Our work indicates that IEEE802.11 as a ad-hoc network is not very suitable for bulk transfer using TCP. It also indicates that it is much better for real-time audio. Although one has to be careful here since real-time audio does require much less bandwidth than the wireless link bandwidth. Careful and detailed studies are needed to further clarify that issue.Comment: 9 pages, 5 figures, ICT 2003 (10th International Conference on Telecommunication

Distributed scheduling with end-to-end compensation in multihop ad hoc networks

In this paper, we investigate the problem of providing QoS to end-to-end flows in multihop ad hoc networks with channel errors through packet scheduling. Each flow is associated with some QoS requirement, which is requested and granted in the form of a desired service rate. The achieved rate is estimated at the destination and fed back to the source periodically. Both the desired rate and achieved rate of a multihop flow are piggybacked on the packets of the flow and propagated from the source node to all its downstream relaying nodes. With such information, a compensation-capable scheduling algorithm originally designed for infrastructured wireless networks can be adapted to each ad hoc node for compensating a lagging flow, i.e., a flow with the achieved rate smaller than the desired rate. We propose the feedback and propagation mechanism as an end-to-end compensation framework, which is the key contribution of this work. We use BGFS-EBA, a scheduling algorithm for infrastructured wireless networks, as an example to demonstrate how such an algorithm is adapted to ad hoc networks within the proposed framework. Our simulation results show that the proposed mechanism maintains outcome fairness and compensate flows that suffer sporadic bursty channel errors effectively. © 2008 IEEE.published_or_final_versionThe 19th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Cannes, France, 15-18 September 2008. In Proceedings of 19th IEEE PIMRC, 2008, p. 1-

Distributed opportunistic scheduling in multihop wireless ad hoc networks

In this paper, we introduce a framework for distributed opportunistic scheduling in multihop wireless ad hoc networks. With the proposed framework, one can take a scheduling algorithm originally designed for infrastructure-based wireless networks and adapt it to multihop ad hoc networks. The framework includes a wireless link state estimation mechanism, a medium access control (MAC) protocols and a MAC load control mechanism. The proposed link state estimation mechanism accounts for the latest results of packet transmissions on each wireless link. To improve robustness and provide service isolation during channel errors, the MAC protocol should not make any packet retransmissions but only report the transmission result to the scheduler. We modify IEEE 802.11 to fulfill these requirements. The MAC load control mechanism improves the system robustness. With link state information and the modified IEEE 802.11 MAC, we use BGFS-EBA, an opportunistic scheduling algorithm for infrastructured wireless networks, as an example to demonstrate how such an algorithm is converted into its distributed version within the proposed framework. The simulation results show that our proposed method can provide robust outcome fairness in the presence of channel errors. ©2008 IEEE.published_or_final_versio

Efficient Resource Management Mechanism for 802.16 Wireless Networks Based on Weighted Fair Queuing

Wireless Networking continues on its path of being one of the most commonly used means of communication. The evolution of this technology has taken place through the design of various protocols. Some common wireless protocols are the WLAN, 802.16 or WiMAX, and the emerging 802.20, which specializes in high speed vehicular networks, taking the concept from 802.16 to higher levels of performance. As with any large network, congestion becomes an important issue. Congestion gains importance as more hosts join a wireless network. In most cases, congestion is caused by the lack of an efficient mechanism to deal with exponential increases in host devices. This can effectively lead to very huge bottlenecks in the network causing slow sluggish performance, which may eventually reduce the speed of the network. With continuous advancement being the trend in this technology, the proposal of an efficient scheme for wireless resource allocation is an important solution to the problem of congestion. The primary area of focus will be the emerging standard for wireless networks, the 802.16 or “WiMAX”. This project, attempts to propose a mechanism for an effective resource management mechanism between subscriber stations and the corresponding base station

Hybrid Wireless Network Approach for QoS

Fast improvement of wireless networks has stimulated variety of wireless applications that have been used in number of areas such as commerce, emergency services, military, education, and entertainment. As wireless communication capture popularity, specific research has been devoted to supporting real-time transmission with Quality of Service (QoS) requirements for wireless network applications. At the same time, a wireless hybrid network that combines a mobile wireless ad hoc network (MANET) and a wireless infrastructure network has been considered to be a better option for the next generation wireless networks. By directly implementing resource reservation-based QoS routing for MANETs, hybrids networks inherit invalid reservation and race condition problems in MANETs

Stable Wireless Network Control Under Service Constraints

We consider the design of wireless queueing network control policies with particular focus on combining stability with additional application-dependent requirements. Thereby, we consequently pursue a cost function based approach that provides the flexibility to incorporate constraints and requirements of particular services or applications. As typical examples of such requirements, we consider the reduction of buffer underflows in case of streaming traffic, and energy efficiency in networks of battery powered nodes. Compared to the classical throughput optimal control problem, such requirements significantly complicate the control problem. We provide easily verifyable theoretical conditions for stability, and, additionally, compare various candidate cost functions applied to wireless networks with streaming media traffic. Moreover, we demonstrate how the framework can be applied to the problem of energy efficient routing, and we demonstrate the aplication of our framework in cross-layer control problems for wireless multihop networks, using an advanced power control scheme for interference mitigation, based on successive convex approximation. In all scenarios, the performance of our control framework is evaluated using extensive numerical simulations.Comment: Accepted for publication in IEEE Transactions on Control of Network Systems. arXiv admin note: text overlap with arXiv:1208.297