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In this paper, we focus on the bandwidth allocation issue in wireless access networks, which are made up of Ethernet Passive Optical Network (EPON) and Worldwide Interoperability for Microwave Access (WiMAX) networks, i.e., Fiber-Wire (FiWi) networks. Since the bandwidth allocation scheme largely determines the performance of the entire wireless access network, in the past decades, researchers have...
Radio Resource Management (RRM) techniques used in the Worldwide Interoperability for Microwave Access (WiMAX) can provide for many of the services and features promised by 4G wireless networks, such as supporting multimedia services with high data rates, and wide coverage area, as well as all-IP with security and Quality of Service (QoS) support. The IEEE 802.16 standard, associated with the WiMAX,...
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...
This paper presents the key design factors that must be taken into account when developing resource allocation algorithms. IEEE 802.16e standard does not include a scheduling algorithm for the uplink direction and it remains open for research and continuous improvement. Using OPNET, we investigate different factors that impact the UL resource allocation in WIMAX. Based on one of our previous papers...
In IEEE 802.16e WiMAX networks, burst is the system resource allocated by BS for users to receive or transmit data. Due to the limitation in system resource, designing an efficient way for BS to allocate the burst to MS becomes important. In general, burst allocation is regarded as the determination of the shape, location, and the modulation scheme of each burst, and it has been proved an NP problem...
WiMAX with femto cells is a cost-effective next generation broadband wireless communication system. Cognitive Radio (CR) has recently emerged as a promising technology to improve spectrum utilization by allowing dynamic spectrum access. There will be large potential benefits by applying the CR technique to WiMAX with femto cells, which are barely explored in the literature. In this paper, we propose...
The IEEE 802.16 standard, also known as WiMAX, provides a mechanism to create a multi-hop mesh network. In order to improve the performance, multi-channel transmission can be adopted, however, a heavy scheduling scheme will affect network performance. This paper proposes a novel algorithm, called Layered Critical Path (LCP), which is a channel assignment scheme in a multi-channel single-transceiver...
In this paper, we consider an uplink multiservice networks employing Orthogonal Frequency Division Multiple Access (OFDMA) for WiMAX networks. Since the OFDMA physical resource available for scheduling is frame by frame, the uplink scheduler located at base station (BS) must efficiently allocate available resources to the subscriber stations (SSs) in response to constant or bursty data traffic on...
Frequency reuse during access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since areas covered by relay stations (RS) or base station (BS) may overlap, some mobile station (MS)s on the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the...
Femtocells are a promising solution for the provision of high indoor coverage and capacity. Furthermore, OFDMA-based femtocells have proven to be highly versatile when dealing with cross-layer co-channel interference thanks to the allocation of frequency subchannels. However, concerns still exist related to the impact of the different access methods to femtocells in an overlayed network. Femtocells...
WiMax mesh network provides a mechanism for creating multi-hop mesh, which can be deployed as high speed wide area wireless network. The routing and scheduling are two key factors that influence the performance of the WiMax mesh networks. In this paper, we introduce cross-layer design scheme and take both routing and scheduling into account in order to improve the performance. A centralized scheduling...
This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used...
The network planning aims to allow the maximum number of users and throughput in a network. This imposes a demanding performance requirement on the new relay-based architecture for mobile WiMAX, in which the capacity estimation is complex. In the network design process, where interference avoidance plays an important role, WiMAX supports reconfiguration of the subchannel usage with some frequency...
AMC (adaptive modulation and coding) is an important technology adopted by IEEE 802.16. Based on AMC, we introduce a frequency domain scheduling and subchannel resource allocation algorithm (FDSA) in this paper for IEEE 802.16 OFDMA systems. According to this algorithm which is applied in physical layer, the paper also proposes a simple AMC link adaptive mechanism. In different conditions, the throughput...
Built on the basis of the classified subscribe station (SS) priorities, a policy-based call admission control scheme is proposed to maximize the system bandwidth throughput and decrease the network delay at the base station(BS) in IEEE 802.16d system. In the simulation, we use throughput comparison and the delay increasing trend as the evaluating criterions. The simulation results show that our proposed...
In wireless mesh networks, the end-to-end throughput of traffic flows depends on the path length, i.e., the higher the number of hops, the lower becomes the throughput. In this paper, a fair end-to-end bandwidth allocation (FEBA) algorithm is introduced to solve this problem. FEBA is implemented at the medium access control (MAC) layer of single-radio, multiple channels IEEE 802.16 mesh nodes, operated...
Indoor wireless communication systems have been developed to improve cell coverage and throughput with low cost in indoor environment. Among several indoor wireless communication systems such as mobile WiMAX (worldwide interoperability for microwave access) system, WPAN (wireless personal area network) and WLAN (wireless local area network), the mobile WiMAX is one of the promising next-generation...
We propose a virtual bidirectional connection for efficient bandwidth allocation to downlink TCP data and uplink acknowledgment (ACK) in mobile WiMAX networks based on IEEE 802.16. We observed that, in serving a downlink TCP flow, the standard bandwidth-request/allocation mechanism inevitably results in additional delay to transmit uplink TCP ACK, which increases round trip time of downlink TCP flow...
In this paper, we study adaptive bandwidth allocation for TCP-based best effort traffic in IEEE 802.16j networks with relay stations. We consider the effect of bandwidth asymmetry on the performance of TCP and take into account the current traffic profile and network channel condition for each subscriber station. We then propose an adaptive scheme which enhances the system aggregate throughput and...
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