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Adaptive Modulation and Coding (AMC) is one of key technologies in 4G system. Band AMC technique enables the Orthogonal Frequency-Division Multiple Access (OFDMA) system to achieve their maximum throughput by efficient utilization of wireless channel characteristics. Band AMC with the adjacent subcarrier allocation specified in 4G system (Worldwide Interoperability for Microwave Access (WiMAX) standard)...
We consider joint relay selection and link scheduling to maximize the network throughput in relay-assisted cellular networks. The spatial reuse is leveraged by scheduling multiple links to simultaneously transmit. The coupling among relay selection, link scheduling, and the interference that is introduced by simultaneous transmissions makes this problem hard to solve. We summarize spatial reuse into...
With the coexistence of various wireless technologies, next generation wireless communications will likely consist of an integrated system of networks, where the Access Points (APs) and Base Stations (BSs) work together to maximize the mobile-user Quality of Service (QoS). In such heterogeneous environment where handheld devices with different access technologies are not uncommon, it should be possible...
The increasing demands for multimedia applications with various QoS requirements arouse the interest of researchers in the Fourth-generation wireless networks such as WiMAX. In order to ensure that the QoS requirements of these applications are met, effective scheduling algorithms must be designed. Even though it may be trivial to ensure that the minimum QoS of all service classes is attained, this...
IEEE 802.16 mesh mode is positioned to be used as a wireless backbone network. In coordinated distributed scheduling (C-DSCH), when nodes transmit control messages to compete for channel access, they need to wait for some period of time called hold-off time to compete again. Network performance is sharply affected by the hold-off mechanism in the bandwidth reservation procedure. In this paper, a new...
IEEE 802.16j is an extension of IEEE 802.16 to support relay mode operation. This paper applies IEEE 802.16j to vehicular networks to provide Internet access for high-way vehicles. It designs a utility function, which considers different types of services and effect of velocity on vehicular networks. It proposes a dynamic bandwidth allocation (DBA) algorithm specifically for base stations (BSs) in...
The seamless integration of heterogeneous wireless access networks is currently one of the issues of major interest in the field of telecommunication systems. In an early future technologies like UMTS, WLAN and WiMAX will give broadband access to users that perform their voice/video calls or data sessions without knowledge of the specific technology their terminals are using, following the paradigm...
The IEEE 802.16 mesh network is a promising next generation wireless backbone network. Under Coordinated Distributed Scheduling (CDS) mode, setting the holdoff time for nodes is essential to achieving good performances of medium access control layer scheduling in the networks. In this paper, we propose a dynamic scheme for setting holdoff time in IEEE 802.16 mesh mode with CDS. This scheme allows...
The IEEE 802.16d mesh mode allows control of the holdoff time for individual nodes, and thus it is possible to adapt the control channel of the local network to different network scenarios and through appropriate configuration of the holdoff time to improve the network throughput. This paper presents an algorithm for distributed scheduling mode that dynamically adjusts appropriated parameters, with...
In order to improve network coverage and throughput at low cost, a mesh mode is defined in IEEE 802.16 standard recently. Although the standard defines the multiple access signaling mechanisms, it doesn't specify resource allocation issue. In this paper, we address the problem of resource allocation with the goal of achieving optimization network throughput in WiMax mesh networks. We first establish...
In this paper, we consider a multi-hop relay networks in IEEE 802.16j system with the full frequency-reuse capability, in which a frame structure can be asymmetrically divided into two different intervals, one for access zone to base station (BS)/relay station (RS)-mobile stations (MSs) communication and the other for relay zone to BS-RS communication, while the same radio resource is fully reused...
The amendment of 802.16e has been released lately by IEEE 802.16 Relay Task Group j. For the sake of improving throughput and extension of cell coverage, relay stations (RSs) are deployed in the network. Intuitively, the base station (BS) selects a path for a target subscriber station (SS) according to Signal to Interference plus Noise Ratio (SINR) or the available bandwidth. However, it will lead...
Most of recent mobile equipment now supports different network technologies (WiFi, WiMax, LTE, Bluetooth and such like). Meanwhile, network operators offer services through these different technologies. The superposition of the different technologies (using different frequency band) increases the potential throughput of the system and hence global performance.
Recent mobile equipment (as well as the norm IEEE 802.21) offers the possibility for users to switch from one technology to another (vertical handover). This allows flexibility in resource assignments and, consequently, increases the potential throughput allocated to each user. In this paper, we design a fully distributed algorithm based on trial and error mechanisms that exploits the benefits of...
In this paper, a dynamic priority-based resource allocation (DPRA) scheme is proposed for uplinks in IEEE 802.16 wireless communication systems. The goal of the DPRA scheme is to maximize the system throughput while satisfying diverse QoS requirements. Four types of multimedia traffic are considered, where these multimedia traffic are given urgency degrees via dynamic priority values, and the radio...
The IEEE 802.16 standard is currently one of the most interesting broadband wireless access. One key issue of mesh networks is the MAC (Medium Access Control) layer. The scheduling and assignment of transmission opportunities can be realized in centralized or distributed manner. In this paper we analyze the IEEE 802.16 election based mechanism for the Coordinated Distributed Scheduling (CDS). In order...
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