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Wireless mesh networks (WMN) are efficient and low cost solutions for the deployment of broadband access in various environments. To support real-time applications such as multimedia and emergency services, WMNs must provide quality of service (QoS) guarantees and QoS continuity protection. While the capacity of single radio WMNs may severely limit the QoS for such traffic, multiradio WMNs can overcome...
In the IEEE 802.11 networks a data packet is delivered to multiple receivers through the multicast paradigm. Since multicast has not a feedback scheme, the reliability of the service provided to the user is penalized. This issue is more important as the network load or the coverage area increases. These two facts cause collisions or corrupted delivery due to bad channel conditions, respectively. In...
The handover performance is critical to support multimedia services in the wireless networks. The algorithm should allow fast selection of the most suitable Access Point. However, in most solutions the handover is reactive and causes Mobile Station to reassociate with the Access Point that offers the strongest received strength signal at a time. The station may miss the chance to handover to the Access...
In 3G long term evolution (LTE) systems, the random access channel (RACH) is used for initial access, resource request, and handover. Since the random access delay is determined by the arrival rate of the random access preambles and the number of RACH subframes, we should configure the number of RACH subframes given the arrival rate in order to guarantee the delay performance. In this work, by carefully...
Infrastructure-based mobile networks are becoming increasingly overloaded due to strong growing number of mobile devices like smartphones and their communication needs. Especially in urban cities the cost of maintaining and extending infrastructure is high due to increased geographical density of mobile devices. While this increasing density puts high load on infrastructure-based networks, it is an...
We investigate a transport layer protocol design that integrates 3G and WiFi networks, specifically targeting vehicular mobility. The goal is to move load from the expensive 3G network to the less expensive WiFi network without hurting the user experience. As the test platform we choose a nationwide 3G network and a commercially operated metro-scale WiFi network. We exploit the often complementary...
The paper presents a network simulator specifically designed for the analysis of real-time wireless networks in an industrial control context, and for time-space localization applications. Critical issues associated to physical components are accounted for, together with the performance of the communication channel in an interfering environment. A comparison toward already available simulation schemes...
3G networks are currently facing severe traffic overload problems caused by excessive demands of mobile users. Offloading part of the 3G traffic through other forms of networks, such as Delay Tolerant Networks (DTNs), WiFi hotspots, and Femtocells, is a promising solution. However, since these networks can only provide intermittent and opportunistic connectivity to mobile users, utilizing them for...
Consider a backoff algorithm for medium access in wireless networks where a node chooses with probability 1−q to transmit right away and with probability q to transmit after CW slots, where CW is the maximum value of the contention window. We study a variation of the 802.11 protocol called XVBEB which uses the above backoff scheme and give a theoretical analysis of its saturation throughput. Simulation...
We present an analytical model to evaluate the performance of the IEEE 802.11 Distributed Coordination Function (DCF) with and without the RTS/CTS handshake in radio-over-fiber (RoF) wireless LANs. The model captures the effects of contending nodes as well as hidden terminals under non-saturated traffic conditions assuming large buffer sizes. The effect of fiber propagation delay is considered. The...
This paper addresses the issue of supporting time-sensitive multiplayer games in a single hop ad-hoc network. We first propose an analysis of the gameplay experience in such network. To this end, we conducted several experiments of an FPS (First Person Shooter) game over a real ad-hoc network. The poor performances experienced when the number of players reaches a certain value (11, in our scenario)...
In Vehicle Ad hoc Networks (VANETs), multi-hop broadcast is a key technique to disseminate emergency information such as Event-driven safety messages to warn drivers in case of dangerous events. When multiple vehicles receive an emergency message, packet collisions may occur if they rebroadcast the message simultaneously. In this paper we propose a power-control broadcast scheme based on studying...
In this paper, we propose a new metric that is applicable both to routing and rate adaptation in multi-rate wireless mesh networks. Unlike many previous efforts, our metric is comprehensive; it considers several factors that affect end-to-end performance such as the effect of the relative positions of the links on a path when choosing the rates of operation and the importance of avoiding congested...
The increase in data consumed by smartphones is becoming a huge problem for mobile operators. In three years, mobile data traffic in AT&T's network rose 5000%. The US operators invest $50 billion in the data networks every year and the technology upgrades and innovation still fail to keep up with the demand. In this paper we design two algorithms for delay-tolerant offloading of bulky, socially...
We analyze the problem of buffer sizing for TCP flows in 802.11-based Wireless Mesh Networks. Our objective is to maintain high network utilization while providing low queueing delays. The problem is complicated by the time-varying capacity of the wireless channel as well as the random access mechanism of 802.11 MAC protocol. While arbitrarily large buffers can maintain high network utilization, this...
Handover efficiency in wireless packet switched networks is very crucial in providing QoS guarantees to real time applications. Mobile IPv6 (MIPv6) is a prevalent choice for mobility management in future generations networks. Although MIPv6 benefited from the design knowledge of its predecessor i.e. MIPv4 and is more efficient, it still suffers from high handover delays. The main reason for MIPv6...
This paper investigates application of a two-tier wireless network system with integrating wireless access and wireless backhaul as the evolution path of providing rural areas with Internet services. The first tier of the proposed network system is the wireless access network which provides interface to user accessing to Internet and enjoy services such as voice over IP, web browsing, and social network...
This paper presents RegionDCF, a self-adapting media access control protocol for WLAN that seamlessly behaves as CSMA or round-robin access techniques taking advantage of the most effective properties of each access method. In contrast to preceding works in this area that focused on enhancements of each protocol, or on a mechanism that switches between them, this paper proposes a single access method...
In this paper, we present a method for minimizing multi-hop transmission delay by optimally setting data rate along selected paths in Multi-hop Wireless Network (MHWN) based on multi-hop activity aware delay analysis. We develop an analytic model that enables us to obtain closed form expressions for delay in terms of multi-hop activity variables. A measuring deviation algorithm is used to derive the...
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