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WiMAX technology provides a Quality of Service (QoS) system that allows system operators to configure a network to provide maximum performance compared to conventional Best Effort (BE) systems. In this paper, we address the increase in number of data rich mobile devices and the performance issues associated with Video On Demand (VOD) multimedia traffic over a WiMAX network. We present the results...
Hybrid wireless networks have been identified as a promising solution to establish communication over vehicular systems that can overcome the current and future needs for increasing public safety and efficiency. In this paper a heterogeneous hybrid vehicular wireless network consisted of IEEE 802.11b/g/e and IEEE 802.16e is being deployed inside a tunnel environment for surveillance reasons. Furthermore,...
Public transportation is vital in everyday life. As a consequence, the increasing need for intelligent surveillance systems over public transportation provides promising areas for wireless vehicular communication research for in-tunnel applications. This paper particularly emphasizes on tunnel implementation regarding to a prototype surveillance system on railway environments based on autonomous,...
Multihop relaying in WiMAX networks is considered an increasingly attractive technology for providing throughput enhancement, coverage extension, or both. In this paper, we consider deploying non-transparent relay stations (RSs) that transmit on the same carrier frequency as the base station (BS) for the purpose of coverage extension. Since it is possible that the RSs and BS are transmitting/receiving...
In IEEE 802.16j-based relay networks, frequency reuse by RS(Relay Station)s and BS(Base Station) is considered as a way to improve the frequency utilization. However, since the same frequency band is used by RSs and BS, MS located in the middle between neighboring transmitting stations suffer severe interference or even outage. This co-channel interference within a cell is a major bottleneck in providing...
WiMAX (Worldwide Interoperability for Microwave Access) is a technology for wireless broadband and the core techniques for the fourth-generation (4G) wireless mobile communications. WiMAX is a new broadband wireless access technology that provides very high data throughput over long distance in a point-to-multipoint environment. There are two main classes of WiMAX system called fixed WiMAX and mobile...
Broadband Wireless Access (BWA) offers QoS-aware broadband access through a wireless medium, being IEEE 802.16 one of the BWA standards. In it, the Base Station (BS) is responsible of allocating the required bandwidth by the rest of nodes, acting as a central controller. The other nodes, Subscriber Stations (SSs), have to send a bandwidth request to give the BS the knowledge about their needs, taking...
In this paper, we propose a bit and power allocation strategy for adaptive modulation and coding (AMC) based spatial multiplexing multi-input-multi-output (MIMO) orthogonal frequency division multiple access (OFDMA) systems. This strategy aims to maximize the average system throughput by allocating the available resources optimally among the utilized bands depending on the corresponding channel conditions...
The base station in IEEE 802.16, or WiMAX, networks allocates contention-based time slots for the mobile stations to transmit their requests for additional bandwidth. Using a technique called subchannelization, multiple concurrent transmissions by mobile stations can be admitted by the base station during the same contention period. For transmission during this period, each station employs a contention-resolution...
IEEE 802.16j mobile multi-hop relay network is proposed to enhance the system coverage, user throughput and the capacity of fixed/mobile broadband wireless access system in IEEE 802.16d/802.16e. Relay station (RS) enables data transmission between base station and end user when the channel is not good for transmission. Besides, one relay station also communicates with a pair of other relay stations...
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...
Orthogonal frequency-division multiple access (OFDMA) is one of the most important modulation and access methods for the future mobile networks. Before transmitting a frame on the downlink, an OFDMA base station has to invoke an algorithm that determines which of the pending packets will be transmitted, what modulation should be used for each of them, and how to construct the complex OFDMA frame matrix...
IEEE 802.16e WiMAX standard classifies packets in the decreasing order of priority as UGS, RTPS, eRTPS, nRTPS, BE. This mechanism of classification is application dependent and a user will not be able to request for a change in priority even though higher priority traffic bandwidth might be available and the user is ready to pay more for elevation of low priority traffic to higher priority. We propose...
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...
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...
IEEE 802.16 network has quickly been deployed in worldwide in recent years. However the signal transmitted by the Base Station is susceptible to shadows of buildings, therefore resulting in a poor signal quality received by Mobile Station. For this reason, IEEE 802.16j intends to improve the above mentioned network problems incurred from IEEE 802.16 through relay station. This allow IEEE 802.16j network...
Random access channel is incorporated in IEEE 802.16 WiMAX system to transport contention-based messages in the uplink, such as bandwidth requests generated by best effort applications, from mobile stations (MSs) to the base station(BS). Regarding the packet transmissions in the random access channel, delay, throughput and power consumption are usually considered as major performance metrics. We propose...
In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of existing and future wireless systems. Several standards support these techniques such as the wireless metropolitan area network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beamforming and Space Division Multiple Access (SDMA) techniques, adaptive antennas are able to...
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...
IEEE 802.16j multi-hop relay task standard includes two mutually exclusive options: transparent relay stations (T-RS) and non-transparent relay stations (NT-RS). In this work, a system design approach is proposed to compare different relay systems in term of their capacity with rate fairness constraint among the mobile stations (MS). Single-input single-output (SISO) and multi-input multi-output (MIMO)...
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