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Wimax is an broadband wireless technology based on IEEE 802.16. It is very helpful and cheaper than other possible solutions. It is purely based on the 4G technology for the upcoming generation. In wireless technology the major problem is speed, Quality of Service, data rates in order to overcome that they going for some valuable technology. In this paper we consider WIMAX and WLAN for controlling...
As an attempt to improve throughput of WiMAX system, the oversampled WiMAX receiver is presented in this paper. Oversampling samples each transmitted symbol more than one time. Thus, several signal sequences which contain different information about channel may be obtained at the receiver. This study presents throughput of the oversampled WiMAX system that obtained by simulation over a realistic channel...
In response to the increasing demand for asynchronous mass data exchange even by mobile users, the DTN-related technologies are considered promising for an efficient use of limited network resources and low-cost deployment at the expense of communication delays. The authors previously proposed a Virtual Segment concept aiming at a practical network infrastructure combining Internet-connected broadband...
Currently evolving wireless communication systems (e.g. LTE-A, WiMAX) are based on linearly precoded MIMO OFDM and utilize adaptive modulation and coding to adjust the code rate and modulation alphabet to the current channel conditions. For this purpose the transmitter requires channel knowledge, which is provided by means of receiver feedback, utilizing the rank, precoding matrix and channel quality...
With the development of novel access technologies e.g. LTE, WiMAX etc., the mobile devices are able to establish services over multiple wireless connections with different momentary capabilities. Being imported from the fixed line communication, the current services deployed are lacking an efficient mechanism of adaptation to the momentary connectivity conditions, which deters the efficiency of the...
In this article we propose a new simulation module for NS-2 able to reproduce the performance of fixed terminals operating in a wireless network with one or more antennas at the receive end, based on empirical models validated on the literature. This is relevant to perform accurate cross layer analyses of fixed wireless systems as Wireless Local Loop, relay networks, WiMax for fixed or repositionable...
A novel coordinated scheduling algorithm for OFDM-based systems in multi-cell scenario is proposed in this paper. The studied algorithm based on the utility function is general for the downlink of networks. The algorithm coordinates the subcarrier assignment over the BS cluster. We first establish the framework for this inter-cell coordinated optimization problem through utility-based method. The...
A wireless backhaul network is used to interconnect intermediate nodes to gateway nodes. As it is designed to serve a large population of broadband users, failure sustainability becomes an essential requirement to ensure uninterrupted telecommunication services even in the presence of occasional node or link failures. In this paper, the performance of a failure sustainable wireless backhaul, based...
In current wireless standards like 3GPP LTE or IEEE 802.16 / WiMAX multiple access is based on orthogonal signalling using single-carrier frequency-division multiple access (SC-FDMA) or orthogonal frequency-division multiple access (OFDMA). Links between a base station and different terminals use mutually orthogonal radio resources. This paper studies potential gains in average cell throughput by...
We propose an effective path selection considering current traffic load for IEEE 802.16j MMR networks. Previous schemes either consider channel quality or the number of hops in choosing the effective path for traffic to MSs. Our scheme avoids crowded links even though they have high channel quality. Our scheme balances between the channel quality and the current traffic load, aiming at higher fairness...
The IEEE 802.16 standards are based on Orthogonal Frequency Division Multiplexing (OFDM) and multi-user OFDM (also known as OFDMA) for their desirable characteristics and potentials. Although well established, these standards only provide a framework of necessary mechanisms for deployable systems. Majority of the resource allocation issues are left unspecified. The conventional one-dimension scheduling...
System capacity is an important factor that affects the performance of WiMAX system where the amount of data that can be delivered to the end user is determined based on the system capacity and users QoS requirements. This scenario is even more complex when multi-hop relays are introduced into the network whereas the user access capacity decreases with the increase of hop number. In order to maintain...
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...
IEEE 802.16j is to enable the operation of multi-hop Relay Stations (RS). It aims to enhance the coverage, per user throughput and system capacity of IEEE 802.16e. However, the Mobile Stations (MSs) which connect to the RS are suffering from exponentially throughput degradation and end-to-end delay increase in congested network. As the number of RS hops increases, so does the degradation and the delay...
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...
WiMAX is the latest technology that has promised to offer broadband wireless access over long distance. The throughput of wireless communication such as WIMAX depends on number of parameters. These parameters include: packet size, transmission rate, signal to noise ratio, modulation techniques and channel conditions. All these variables are discussed using simulation, certain graphs have obtain optimum...
WiMAX is a broadband wireless technology that supports fixed, nomadic, portable and mobile access. For the fixed or portable applications, the channel can be considered as a static. In this paper, we propose to use channel prediction in order to improve the performances of resource allocation algorithms, in term of outage probability and average throughput. Moreover, for a dynamic OFDMA system, when...
Since low-density parity-check codes have near-capacity decoding performance and very high decoding throughput, they have been employed as FEC coding scheme in many transmission standards for wireless communication, such as IEEE 802.22n, IEEE 802.16e, DVB-S2, and DTMB. This trend triggers the need for so-called multi-standard LDPC decoders. In this paper, a flexible architecture that supports multiple...
Orthogonal frequency division multiple access (OFDMA) is an efficient access technique that allocates different subcarriers to multiple users where each subcarrier is loaded with a number of bits belonging to that user. Allocating subcarriers and bits to multiple users has been the focus of many algorithms that attempt to maximize the throughput or minimize the total transmit power used. Non-real...
Modern wireless communication systems employ MIMO and feedback-two properties that make it especially difficult to measure the performance of such systems with reasonable effort in actual outdoor scenarios. In this paper, we will present a time, cost, and manpower efficient measurement approach to evaluate the throughput achieved by such systems. Summer/winter, large distance outdoor-toindoor/outdoor,...
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