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Proceedings ArticleDOI

Performance study of an optical backbone MAC interconnecting WiMAX base stations over a city/county area

TL;DR: This paper proposes optical backbone connectivity operating at 2.5 Gbps for inter networking several WiMAX BSs located in various location of large cities/county and proposes a novel hybrid- MAC protocol that caters to the QoS needs for real time service with negligible jitter and provides minimum delay for non-real time data traffic of WiMAX.
Abstract: WiMAX standard's medium access control (MAC) protocol supports QoS for real time traffic. Single WiMAX can cover 10 Kms with broad band support of around 22 Mbps in downlink and 6 Mbps in uplink [7]. Multiple WiMAX base stations (BSs) are needed to cover a thickly populated city or county with large diameter (i.e., above 20 kms, which is very common). To maintain QoS for inter WiMAX BSs traffic, it is important to have a supportive MAC protocol on interconnecting network (referred as backbone). In this paper we propose optical backbone connectivity operating at 2.5 Gbps for inter networking several WiMAX BSs located in various location of large cities/county. We propose a novel hybrid- MAC protocol that caters to the QoS needs for real time service with negligible jitter and provides minimum delay for non-real time data traffic of WiMAX. The backbone delay for best effort traffic has been analyzed under various circumstances of real time as well as non-real time traffic. Furthermore, the results reveal that with reasonable load on the backbone there is hardly any impact on packet delay for even Best Effort services.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors proposed and investigated the standard WiMAX access in high speed railway (HSR) using radio over fiber (RoF) link and analyzed the effect of the Doppler frequency shift over HSR.
Abstract: In this investigation, we propose and investigate the standard WiMAX access in high speed railway (HSR) using radio over fiber (RoF) link. We also discuss the theory of mobile WiMAX at a target speed of 300 km/hr in simulation. We also analyze the effect of the Doppler frequency shift over HSR. The effective transmission fiber length in the WiMAX-RoF system was limited due to the time-division-duplex (TDD) protocol in the practical WiMAX. Thus, we also demonstrate the transmission limitation and performance of the standard WiMAX access in RoF link. The performances of throughput and packet loss at different fiber lengths are also investigated and discussed. Furthermore, a WiMAX-RoF field trial is also demonstrated based on a simple two RAUs RoF architecture. It was tested and measured in the SongShan tunnel of the Taiwan high speed railway (THSR).

50 citations

Proceedings ArticleDOI
28 Apr 2009
TL;DR: Results show that the effective RoF transmission fiber length can be limited due to the time division duplex (TDD) framing in the connection using standard WiMAX signal generated by a commercial WiMAX bias station.
Abstract: WiMAX is considered for the last mile wireless connectivity to provide flexible broadband services to end users. And Radio over Fiber (RoF) system has attracted industry and research interest to extend the wireless cell coverage and reduce the cost by using the distributed remote antenna units (RAUs). Here, the performance of WiMAX RoF system will be characterized. Results show that the effective RoF transmission fiber length can be limited due to the time division duplex (TDD) framing in the connection using standard WiMAX signal generated by a commercial WiMAX bias station. WiMAX RoF performances of throughput and packet-loss at different link lengths are investigated and analyzed. Besides, a robust TDD switch architecture used in each RAU will be proposed for the WiMAX RoF system.

5 citations

Journal ArticleDOI
TL;DR: In this article, the transmission limitations and performances of the standard WiMAX signal for radio over fiber (RoF) systems were investigated and the throughputs and packet-losses at different flber lengths were analyzed.
Abstract: Radio over Fiber (RoF) system has attracted much industry and research interest to extend the wireless cell coverage and reduce the cost by using the distributed remote antenna units (RAUs). However, the efiective transmission flber length in the RoF systems would be limited due to the time division duplex (TDD) mode used in the practical WiMAX access. Here, we study the transmission limitations and performances of the standard WiMAX signal for RoF systems. The throughputs and packet-losses at difierent flber lengths are also investigated and analyzed. Besides, in order to increase the emitting power of the RAUs, a robust TDD switching mechanism is proposed in each RAU for RoF system.

4 citations

Journal ArticleDOI
TL;DR: The upper bound of the tolerant delay of services in wireless access network is investigated, by mapping core network onto a cost-variable directed graph, where the cost is construed as the average service delay of theows traveling in core network that depends on the current load.
Abstract: With the explosive growth of wireless applications, the subscribers’ requirements of QoS (Quality of Service) are increasing as well. In this paper, the upper bound of the tolerant delay of services in wireless access network is investigated, by mapping core network onto a cost-variable directed graph, where the cost is construed as the average service delay of the flows traveling in core network that depends on the current load. A multicommodity minimal cost flow mathematics problem is then derived and solved by Price-directive Decomposition and Lagrangian Relaxation. Simulations are carried out in two typical core networks and some valuable conclusions are gained.

Cites background from "Performance study of an optical bac..."

  • ...[4] proposes a novel hybrid MAC (Medium Access Control) protocol to satisfy the QoS needs for real-time services and analyzes the minimal delay for non-real-time data traffic in the backbone of WiMAX (World Interoperability for Microwave Access)....

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  • ...[3] and [4] are always carried out not only depending on the protocols and equipments in real networks but also by using professional softwares, while Ref....

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References
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Journal ArticleDOI
TL;DR: This article presents the realistic attainable throughput and performance of expected WiMax compatible systems based on the 802.16d standard approved in June 2004 and suggests future enhancements to the standard that could at least quadruple the achievable data rate.
Abstract: The IEEE 802.16 family of standards and its associated industry consortium, WiMax, promise to deliver high data rates over large areas to a large number of users in the near future. This exciting addition to current broadband options such as DSL, cable, and WiFi promises to rapidly provide broadband access to locations in the world's rural and developing areas where broadband is currently unavailable, as well as competing for urban market share. WiMax's competitiveness in the marketplace largely depends on the actual data rates and ranges that are achieved, but this has been difficult to judge due to the large number of possible options and competing marketing claims. This article first provides a tutorial overview of 802.16. Then, based on extensive recent studies, this article presents the realistic attainable throughput and performance of expected WiMax compatible systems based on the 802.16d standard approved in June 2004 (now named 802.16-2004). We also suggest future enhancements to the standard that could at least quadruple the achievable data rate, while also increasing the robustness and coverage, with only moderate complexity increases

764 citations


Additional excerpts

  • ...16e networks is already well studied [4-5]....

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Journal ArticleDOI
TL;DR: This article focuses on mechanisms that are available in an 802.16 system to support quality of service (QoS) and whose effectiveness is evaluated through simulation.
Abstract: During the last few years, users ail over the world have become more and more accustomed to the availability of broadband access. This has boosted the use of a wide variety both of established and recent multimedia applications. However, there are cases where it is too expensive for network providers to serve a community of users. This is typically the case in rural and suburban areas, where there is slow deployment (or no deployment at all) of traditional wired technologies for broadband access (e.g., cable modems, xDSL). In those cases, the most promising opportunity rests with broadband wireless access technologies, such as the IEEE 802.16, also known as WiMAX. One of the features of the MAC layer of 802.16 is that it is designed to differentiate service among traffic categories with different multimedia requirements. This article focuses on mechanisms that are available in an 802.16 system to support quality of service (QoS) and whose effectiveness is evaluated through simulation

442 citations


Additional excerpts

  • ...16e networks is already well studied [4-5]....

    [...]

Proceedings ArticleDOI
07 May 2006
TL;DR: A central coordinating device combines the central base station of IEEE 802.16 with the hybrid coordinator of 802.11e and is thus referred to as base station hybrid coordinator and is evaluated in this paper.
Abstract: The coexistence and interworking of IEEE 802.16 and IEEE 802.11 is an acute problem. The frame-based medium access of 802.16 requires rigorous protection against interference from wireless local area networks in order to operate properly. The 802.11e enhancements of the medium access control of 802.11 introduce the capability to support QoS. These enhancements define a central entity as main element: The Hybrid Coordinator. It realizes a contention free, centrally controlled medium access and introduces QoS limitations to the contention based access of 802.11e. In this paper, a central coordinating device combines the central base station of 802.16 with the hybrid coordinator of 802.11e and is thus referred to as Base Station Hybrid Coordinator. The Base Station Hybrid Coordinator is capable to operate in an 802.16 and an 802.11(e) protocol mode in the same frequency band. The realization of the interworking between these two standards is discussed and evaluated in this paper.

44 citations

Proceedings ArticleDOI
16 May 2005
TL;DR: It is found that the presence of data traffic does not reduce the number of video-conference calls that can be supported when EDCA is used; this is not the case with DCF, and the performance of both data applications considered is slightly improved by the use of EDCA.
Abstract: In this paper we study the ability of an IEEE 802.11g WLAN to support video-conferencing and data applications. We evaluate the number of simultaneous video-conference calls that can be supported, subject to user perception-based quality requirements, and compare the performance of two MAC protocols: the default distributed coordination function (DCF) protocol and the enhanced distributed channel access (EDCA) protocol. We also assess the effect of the presence of data traffic generated by Web browsing and file transfer applications and the physical size of the network on the number of video conference calls that can be supported. The analysis of the network is carried out by means of simulation; great care is taken to accurately represent the applications and the network, requiring several modifications and additions to the widely-used ns-2 network simulator. At the application layer, traffic is generated using realistic models or real traces, and user perception-based quality metrics (for example, the mean opinion score for voice) are used to assess the network's performance. Within the network, we use accurate representations of the MAC protocols, and use a wireless channel model which incorporates the effect of frequency-selective fading. We find that the presence of data traffic does not reduce the number of video-conference calls that can be supported when EDCA is used; this is not the case with DCF, Furthermore, the performance of both data applications considered is slightly improved by the use of EDCA.

19 citations


"Performance study of an optical bac..." refers methods in this paper

  • ...The encoded bit stream is packetized in RTS packets along with frame header subject to a maximum RTS packet size of 1600 bytes (8 slots) [3]....

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Journal ArticleDOI
TL;DR: The analysis of linked-cluster networks with single-wavelength and wavelength-division multiplexed (WDM) optical backbones, providing interconnection between several clusters, reveals that the probability of intercluster communications has significant impact on the backbone throughput as well as on the end-to-end throughput of the entire network.

4 citations


"Performance study of an optical bac..." refers methods in this paper

  • ...Copper or, wireless networks employ variants of CSMA strategy to avoid collisions, but CSMA based techniques are impractical to implement in optical domain since a packet duration is much smaller compared to propagation delay [1-2]....

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