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A multihop relay extension for IEEE 802.16e systems is the subject of ongoing standardization activities within the IEEE 802.16j Task Group. The emerging IEEE 802.16J standard enhances the 802.16e PHY and MAC to enable support of multihop routes between a mobile station and a base station through intermediate relay stations. Since it is believed that the capacity of a single-hop 802.16e system is...
The energy saving mechanism is very important for supporting the mobility and extending the battery life in the wireless packet access network. For example, the sleep-mode has been standardized in both IEEE 802.16e and 3G long term evolution (LTE) systems. According to the definition in the standards, an adaptive energy saving mechanism (AESM) for enhancing the standardized energy saving mechanism...
Aiming at the periodical data gathering application of Wireless Sensor Network, this paper first analyzed the network traffic flow and transmission delay in typical aggregation model. Then it investigated how to properly allocate aggregation time to minimize total network traffic within certain delay bound. An optimization problem was deduced and numerical solutions for regular network are calculated...
In the last years the wireless metropolitan area networks have increased their popularity and attracted the interest of the most important research groups all over the world. Several standards have been defined, in particular IEEE 802.16 has taken a relevant role in achieving a full-service broadband wireless network all over a urban and suburban area. This paper deals with the resource allocation...
Different types of power-saving techniques have been proposed in various fields to alleviate the limitation on the battery lifetime for the mobile stations (MSs). In order to provide feasible energy-conserving mechanism, three different power-saving types have been introduced in the IEEE 802.16e broadband wireless networks. By means of pre-negotiations, the MS can be absent from the serving base station...
Data rate adaptation aims to select the optimal data rates for current channel conditions leading to substantial performance improvement. This paper proposes a data rate adaptation technique that: (1) exploits the periodic IEEE 802.11 beacons; (2) discriminates between frame losses due to channel fading and those due to collisions and takes actions appropriate for each type of loss; and (3) recommends...
Although transmission policy is crucial in extending lifetime of sensor networks, most existing policies make simplified assumptions which include: i) circular cluster with cluster head (CH) at the center, ii) uniform periodic data generation model and iii) unrestricted transmission range for nodes. But, in practice, these assumptions are too restrictive for real-world deployment of heterogeneous...
The aim of this paper is twofold. On one hand, it presents a multi-dimensional Markovian state transition model characterizing the behavior at the medium access control (MAC) layer by including transmission states that account for packet transmission failures due to errors caused by propagation through the channel, along with a state characterizing the system when there are no packets to be transmitted...
IEEE 802.11 is now being used in many situations where access point (AP) power saving would be highly desirable. Unfortunately, this is not possible since the existing standard requires that APs remain active at all times. In this paper, we present a framework for a power saving quality-of-service (QoS) enabled access point (PSQAP), intended for use in low power infrastructure applications. The proposed...
In this paper, we propose a technique for predicting the traffic pattern of primary users in cognitive radio systems. Cognitive radios enable sharing the frequency bands that are licensed to primary users. By forecasting the traffic pattern of primary users, secondary users can estimate the utilization of frequency bands and select one for radio transmission to reduce the frequency hopping rate (the...
This paper presents the design of VoIP optimized packet scheduler and performance simulations for supporting voice services over downlink evolved UTRA. An efficient packet scheduler taking into account the traffic characteristics and adopting optimal resource allocation is proposed. Results are given for different control channel number settings and packet bundling options. Simulation results show...
A utility based resource allocation scheme is investigated for improving system performance of 802.16 OFDMA systems supporting a mix of multi-media traffic types. We show that a utility based approach can improve system capacity over conventional proportional-fair resource allocation schemes through more efficient allocation of only the required resources demanded by the QoS profile of each traffic...
Performance comparison of control-less scheduling policies for VoIP in LTE UL is conducted in this work. In LTE system, the main challenges of effectively supporting VoIP service are the control channel restriction from the large number of simultaneous users and the frequent arrival of small packets. Semi-persistent scheduling and group scheduling are the main methods to solve above problem and achieve...
The use of 802.11-based multi-hop wireless mesh networks for Internet access is extensive and growing. The primary advantages of this approach are ease of deployment and lower cost. However, these networks are designed for web and e-mail applications. Highly interactive applications, such as multiplayer online games and VoIP, with their requirements for low delay, present significant challenges to...
Streaming and multimedia services are key applications in UWB-based high-rate short-range wireless personal area networks (WPANs). In this paper, we study how to support the quality of service (QoS) requirement of these services over the distributed TDMA-based WiMedia UWB MAC protocol. We develop an integer-linear programming model to solve the path available bandwidth problem. To reduce the computation...
In this paper, we provide a parametric model for analyzing the control overhead usage In mobile ad-hoc networks (MANET). In particular, we focus on evaluating the Impact of the hierarchy of both topology formation and routing on the scalability of overhead usage. Via an analytical approach, we quantitatively characterize the amount of overhead under different domain sizes, as well as other design...
In a wireless mesh network, a client station needs to associate with a mesh access point for network access. Conventional association mechanisms assume a high-speed backhaul and only the access link being the bottleneck. This assumption holds for most WLANs, but in wireless mesh networks traffic could be bottlenecked either by the access link or by the bandwidth-limited wireless backhaul. In this...
Cognitive radio is known as the technology that can make possible more intensive and efficient spectrum use through spatial and temporal utilization. In cognitive mesh networks where each base station consists of heterogeneous multi-radio interfaces, packet switch in L2/L3 of each base station selects each radio interface and channel adaptively in order to take full advantage of all multiple heterogeneous...
IEEE 802.16 Wireless Broadband is a promising technology for providing last mile access. Quality of Service (QoS) is an important factor that has been addressed by the standard which defines four types of multimedia traffic classes. However resource allocation and scheduling between the traffic classes is vital in providing QoS which the standard has left undefined. In this paper we propose a Markov...
Mobility in ad hoc networks causes routes to break disrupting traffic flows and triggering additional routing overhead. We address this problem with a novel hybrid routing protocol, Aisle Routing. Aisle Routing introduces a route refresh mechanism to reactive source routing which proactively and adaptively refreshes routes through an aisle-like area and is designed so the route-control overhead is...
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