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In this paper, the system capacity of IEEE 802.16j systems operating in transparent mode is investigated under varying numbers of relays and associated transmit power. The study is based on an extended variant of an analytical model defined in previous work and used to determine the throughput gain that can be achieved under a max-min fairness cons...
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... Like the Genc V. et al. [16] present an analytical modal that tries to enhance end-to-end throughput under maxmin fairness constraint. Further by Genc V. et al. [17] extends the same model by incorporating the variable number of relays and transmits power; results show that about 55% to 125% of the throughput gain can be achieved subject to spatial reuse. But the MAXMIN algorithm has an issue that it may increase the throughput of some subscribers but starved the rest of the nodes. ...
Worldwide Interoperability for Microwave Access network accepts the challenge of last mile wireless access for internet. IEEE 802.16 standard, commercially known as WiMAX provide wireless broadband experience to the end subscribers and challenges many wired solutions like Digital Subscriber Line (DSL) and cable internet. Wireless network has many inherent issues like coverage holes; capacity optimization and mobility are few of them. Adding relays to multi-hop WiMAX IEEE 802.16j network present an effective solution to address them to some extent but this amendment does not elaborate any algorithm regarding the relay selection and narrate no performance guarantees. In this work, we proposed linear model that fairly allocates wireless resources among subscribers in 802.16j network. A relay selection algorithm is also presented to optimally select nodes with higher signal-to-noise ratio as relay station for nodes with lower signal-to-noise ratio objectively maximize overall network capacity. This scheme further extends network coverage area and improves network availability. We also did extensive performance evaluation of the proposed linear model. Results show that optimal relays selection scheme do provide a substantial increase of up to 66% in overall network capacity in the fixed WiMAX network. This improvement is substantial at places where network condition is not optimal. Investigating the problem further leads to the conclusion that the relay selection criterion is the key to achieve maximum network capacity.
... Like the Genc V. et al. [16] present an analytical modal that tries to enhance end-to-end throughput under maxmin fairness constraint. Further by Genc V. et al. [17] extends the same model by incorporating the variable number of relays and transmits power; results show that about 55% to 125% of the throughput gain can be achieved subject to spatial reuse. But the MAXMIN algorithm has an issue that it may increase the throughput of some subscribers but starved the rest of the nodes. ...
... The T-RSs (Genc et al., 2009;Upase and Hunukumbure, July 2008) only forward controls information generated by the MMR-BS, and hence they do not extend the coverage area of the BS. However, T-RS is used to enhance the system capacity in terms of throughput within the BS coverage area. ...
... So, the intermediate and the access RSs are not required to transmit control information by themselves. Although the SSs are inside the coverage range of the MMR-BS but by using multiple hops with the aid of RSs higher throughput is achieved (Genc et al., 2009). Thus, the goal of this type of relaying is to enhance network capacity in terms of throughput. ...
Mobile Multi-hop Relay (MMR) WiMAX network uses Relay stations (RSs) to extend the cell coverage, and enhances the link quality and the throughput. In MMR WiMAX networks, the number of hops between the Subscriber stations (SSs) and the Base station (BS) is allowed to be more than two hops when Non transparent RS (NT-RS) is used. However, this requires modification to the frame structure of NT-RS to reduce the delay of relaying the data packets across multiple hops. Therefore, this paper presents a new NT-RS frame structure aimed to decrease the multi-hop relaying delay in order to improve the performance of the data transmission over MMR WiMAX network. The proposed frame structure serves the sub-ordinate SSs as well as NT-RSs in the access zones, while using the relay zones to communicate with its super-ordinate stations. The performance of the proposed frame structure is tested through a simulation work. The results showed that,the forwarding delay is reduced, and hence the link layer and the Transmission control protocol (TCP) throughput are improved significantly.
... However, their work does not mention on the types of traffic generated by the SS. In [11], the system capacity of IEEE 802.16j network using transparent RS have been investigate. In their studies, they evaluate the throughput gains by varying number of RS and relate it with power transmit by the RS. ...
In this paper, we have investigated the use of transparent relay station to improve the throughput of the IEEE 802.16j Mobile Multi-hop Relay (MMR) WiMAX network. Simulations are performed using OPNET Modeler, and only VoIP application is considered. The result shows transparent relay station does improve the throughput of WiMAX network with some coverage extension.
... Otros trabajos como en [5], en el cual se presenta el análisis de la interferencia entre celdas, para determinar la capacidad del UL y DL, en [6] el trabajo realizado está centrado en el análisis analítico de la capacidad del UL además de una simulación en la cual la ganancia que se presenta en estos tipos de sistemas es de hasta un 40%, en [7] se realiza un estudio del comportamiento de estos sistemas de acuerdo a la variación del número de RSs con su potencia de transmisión asociada sobre el DL para determinar la capacidad del sistema en el modo transparente, para lo cual se formula el modelo del sistema empleando un algoritmo desarrollado para Matlab ® . ...
... Experimentalmente se llegó a determinar que el incremento en porcentaje del throughput del sistema es de alrededor del 14%, empleando un total de 6 T-RSs, denotándose una gran diferencia con otros trabajos desarrollados, como en [6] y [7], los cuales presentan que el incremento en porcentaje del throughput es inferior al 6%. ...
This paper studies system uplink capacity in transparent mode with mobile nodes and fixed relays stations in conformance with IEEE 802.16j. The study shows different simulation scenarios for evaluating uplink capacity in a Mobile Multihop Relay (MMR), with varying numbers and different positioning of relay stations in a transparent mode (T-RS), moreover, two environments are considered, an urban and a rural environment. The results show that IEEE 802.16j must be implemented in an urban environment instead of rural environment. The main conclusions determined in this work are the increase of throughput in relationship with the position of the T-RS and the effective number of T-RS that permit the maximum system increase is using 6 T-RS presenting an improvement of 14% of the system capacity.
... The studies of [14], [15] consider using spatial reuse to improve network throughput under the relay architecture. The idea is to first let each MSS select its 'best' path to reach the BS and then check whether some links can be transmitted simultaneously to improve network throughput. ...
... In this way, not only the MSSs' uplink requests can be met but also their energy can be conserved. Simulation results show that when there are 8 RSs and 20 MSSs, the proposed scheme can save up to 80% of MSSs' energy compared to the schemes in [14], [15]. ...
... In addition, to offer multiplexing rate and diversity gain, the 802.16m standard exploits the multicell MIMO to eliminate dominant intercell interferences. However, more technical issues [11] PMP [12] PMP [13] PMP [14], [15] relay [16] relay [17] mesh [18] mesh need to be addressed, such as the synchronization issue, how to report the channel state information, and how to get the pre-coding information from the backhaul network. These issues make the WiMAX scheduling problem more challenging and interesting. ...
WiMAX is developed to support large-scale wireless broadband access. Defined in a series of IEEE 802.16 standards, three architectures of WiMAX networks are proposed to adapt to various environments. The point-to-multipoint architecture is used to manage a few number of devices, where each device is able to directly communicate with the central base station. The relay architecture deploys some special stations to act as intermediary between devices and the base station, where devices can choose whether or not to communicate with the base station through these intermediary. The mesh architecture is deployed to cover a large area, where all devices/stations are organized in an ad hoc fashion. Different challenges are arisen under different network architectures, leading the WiMAX scheduling problem to attract lots of research focus. In this chapter, we discuss the scheduling problems and their solutions under the three architectures of WiMAX networks, which covers the issues of how to improve network throughput, how to guarantee quality of service, and how to reduce energy consumption of devices. The comparison of these scheduling solutions is also given in the chapter. Index Terms—IEEE 802.16, mesh, OFDM/OFDMA, point-to-multipoint, relay, resource management, WiMAX.
... The work [14] adopts a Markov decision process for admission control and a chance-constrained assignment scheme to place the minimum RSs while maximizing their transmission rates. Refer- ence [5] applies the minimal coloring solution to maximize the downlink capacity while reducing the difference among MSs' data rates. However, the above studies focus on enhancing network capacity but do not consider saving MSs' energy. ...
... mW (milliwatt) FFT: fast Fourier transform range of the BS to get the best performance gain [5] and the number of RSs is ranged from 0 to 32. MSs are randomly deployed inside the BS's coverage and the number of MSs is ranged from 10 to 60. ...
... MSs are randomly deployed inside the BS's coverage and the number of MSs is ranged from 10 to 60. We compare our heuristic against the minimal-coloring (MC) scheme [5] and the modified solution of MCK problem (sMCKP) [21]. The MC scheme considers spatial reuse while the sMCKP scheme addresses the energy consumption of MSs. ...
The IEEE 802.16j standard is defined to enhance WiMAX networks with relay capacity. Under the transparent mode, existing studies only target improving network throughput by increasing the transmission rates of mobile stations (MSs) and maximizing concurrent transmissions. However, using a higher transmission rate or allowing more concurrent transmissions could harm MSs in terms of their energy consumption, especially when they are battery-powered. In this paper, we consider the energy-conserved resource allocation problem in the uplink direction of an IEEE 802.16j network under the transparent mode. This problem asks how to arrange the frame usage with satisfying MSs’ demands as the constraint and minimizing their total energy consumption as the objective. We prove this problem to be NP-complete and develop two energy-efficient heuristics, called demand-first allocation (DFA) and energy-first allocation (EFA) schemes. These heuristics employ a gradient-like search method to approximate the optimal solution. Specifically, DFA tries to satisfy MSs’ demands first by using as less frame space as possible. Then, with the remaining frame space, DFA tries to save MSs’ energy by lowering their transmission rates or adjusting their transmission paths. Viewed from a different perspective, EFA first allocates the frame space to MSs to consume the least energy. Since the total allocation may exceed the frame space, EFA then exploits spatial reuse and rate adjustment to pack all demands into one frame. Simulation results show that our heuristics can approximate the ideal performance bounds and save up to 90% of MSs’ energy as compared to existing results.
... In [11], the authors characterized the optimal relay location to minimize the outage probability, and then proposed a nearestneighbor relay assignment scheme where the nearest neighbor to the source is assigned as a relay station. In [12], the authors investigated the system capacity under the varying number of RSs and associated transmit power. The results show that the gain varies from less than 5% to 55% by increasing the number of RSs. ...
Cooperative communications are adopted as a promising solution to achieve high data rate over large areas in the future 4G wireless system, and the relay station (RS) is the key concept in cooperative communications. However, most existing works in this area focus only on optimal RS selections. In addition, there are only few works consider another crucial issue: how many relay stations we need to place. Only when the number of relay stations is defined, the relay station selection can perform well. In this paper we exploit the Erceg B path loss model to create a formula which describes the impact of varying number of RS on end-to-end channel capacity. In addition to mathematical analysis on the feasibility of the formula, we also examine its performance through a set of simulations. Simulation results verify that the capacity gain of our proposed scheme is promising.
... In [4], the system capacity of IEEE 802.16j transparent mode was investigated for different number of RSs and transmission power. The study found that an overall throughput gain of 125% and 55% can be obtained with and without spatial reuse respectively compared to 802.16e system. ...
In this paper, two formulations for planning base station (BS) and Relay Station (RS) locations are proposed: a rather complex 0-1 integer programming model which can be used to determine which set of locations should be selected from a given set of BS and RS locations and a simpler decomposition approach which focuses first on the BS location problem followed by the RS location determination. The two approaches are compared and the results show that the simpler decomposition approach can find solutions using significantly less resources which are very minimally lower in quality than that found by the more complex formulation. Hence, the decomposition approach can be used to solve larger 802.16j network planning problems.
... The aggregate system throughput in the omnidirectional case and the sectorised case are determined under max-min fairness in which approximately equal performance is delivered to all subscribers, in scenarios with and without spatial reuse. The study is a development of previous work [3][4] and two contributions are made in this work. First, inter-cell interference is included into the analytical model [3] and the graph based model [4] used to determine the performance of multicell transparent relay mode 802.16j system under different frequency reuses and antenna types at the BS. ...
... The study is a development of previous work [3][4] and two contributions are made in this work. First, inter-cell interference is included into the analytical model [3] and the graph based model [4] used to determine the performance of multicell transparent relay mode 802.16j system under different frequency reuses and antenna types at the BS. Secondly, guidelines are provided on the system design in order to maximise the gain that can be achieved through transparent relays. ...
... Under some specific assumptions on the system configuration, the work in [4] answers some initial question on the achievable throughput gain with single cell transparent mode 802.16j systems. The paper shows that through the deployment of transparent relays 55% and 125% gain can be achieved in the downlink (DL) over 802.16e systems without and with spatial reuse, respectively. ...
In this paper, the system capacity of a multi-cell IEEE 802.16j system operating in transparent mode is investigated. A previous published analytical model is used and incorporates interference from neighbouring cells. The model can be used to determine downlink performance under max-min fairness constraints for both sectored and omnidirectional systems with different amounts of relays. The study provides guidelines on the design of 802.16j systems operating in transparent mode specifically, how to maximise throughput for such systems. It is shown that inter-cell interference from relays is limited in a suburban environment and that relays can deliver significant gains over single hop systems: gains of 30% and 60% can be achieved without and with spatial reuse in an omnidirectional system while 15% and 25% in a sectorised system.
