Information raining has been shown to address the problem of delivering Internet access to high-speed rail passengers. However, a wireline repeater or heterogeneous wireless relay design complicates implementation. Recent developments in extending mobile multihop relaying to the IEEE 802.16e standard have made it feasible to deploy an information raining using a common radio and physical layer. Two automatic repeat request techniques and two network coding techniques are proposed. An upper and lower bound on delay is established for a single fully network coded relay system operating in static signal to noise ratio conditions. Simulations involving a physical layer model demonstrate that network coding schemes can attain the maximum downlink capacity.

Information raining has been shown to address the problem of delivering Internet access to high-speed rail passengers. However, a wireline repeater or heterogeneous wireless relay design complicates implementation. Recent developments in extending mobile multihop relaying to the IEEE 802.16e standard have made it feasible to deploy an information raining using a common radio and physical layer. Two automatic repeat request techniques and two network coding techniques are proposed. An upper and lower bound on delay is established for a single fully network coded relay system operating in static signal to noise ratio conditions. Simulations involving a physical layer model demonstrate that network coding schemes can attain the maximum downlink capacity.

IEEE 802.16相關標準已經發展出像是已經成熟的802.16d、支援移動性的802.16e還有支援Multihop Relay (MR)的802.16j。802.16j的特點就是多了可以轉傳資料的Relay Station (RS)，藉由RS可以擴大網路覆蓋範圍(coverage extension)並提升系統傳輸效能(throughput enhancement)，不過也因此使得802.16j的topology不同於以往，變成類似Tree的架構，傳輸路徑也不再是單純的single hop，有可能變成two hop甚至multihop的方式，也因此產生了新的多重路徑(multipath)問題：BS和MS中間的路徑不再唯一，因此路徑也需適時的配合改變，否則可能會嚴重的影響效能。 本文以連線的QoS（Quality of Service）要求為標準，依照系統中delay需求順序建立連線BS與RS間的連線，最後建構出系統的tree topology並依此進行傳送。目的在讓高QoS連線與BS間的Hop數降低，達到降低delay並穩定jitter的目標，並提供congestion control。最後利用NS-2網路模擬器對不同的網路環境進行模擬，測試所產生的效能並進行評估，以驗證此方法的實際可行性。

In IEEE 802.16j MMR (Mobile Multi-hop Relay) networks, bandwidth is divided into two zones, access zone to mobile stations and relay zone to relay stations. To satisfy the requirements of Quality of Services (QoS) for different types of traffic between access zone and relay zone, we propose Bandwidth-Negotiation Scheduling (BNS) for BS and RS to adequately allocate bandwidth. For the purpose of satisfying higher-priority rtPS traffic, BNS can negotiate bandwidth between two zones if the allocated bandwidth is insufficient to meet its QoS requirement. Besides, BNS can satisfy bandwidth requirement for nrtPS as much as possible and it will also do negotiation to allocate at least minimum bandwidth if resource is not sufficient. At last, BNS may reduce the allocated bandwidth for nrtPS if PLR (Packet Loss Ratio) of BE is too high. Therefore, the starvation probability of BE can be decreased by earning this extra bandwidth from nrtPS. In short, the proposed BNS can adjust the boundary between access zone and relay zone dynamically and it can improve bandwidth utilization effectively. Through Markov-chain model, we evaluated the performance of BNS and compared its performance to a mechanism with fixed-boundary. Analytical results have shown that BNS can decrease the probability of exceeding delay constraint for rtPS, increase the throughput, and decrease the PLR for nrtPS when rtPS delay constraint is increased. Moreover, BNS can significantly reduce the possibility of starvation for BE traffic.

IEEE 802.16標準中有所謂Mobile Multi-hop Relay（MMR）的概念，然而基地台覆蓋範圍不足及遮蔽效應等問題尚待解決，因此在IEEE 802.16j標準中提出Relay Station（RS）以提升網路傳輸量並增進無線通訊品質。在MMR中由於多了中繼傳輸站來傳遞資料，因此需要有較多的連線頻道，此外也不能保證所有頻道都處於良好狀態，所以會有很高的機率造成資料傳送失敗。混和自動重傳要求（Hybrid Automatic Repeat reQuest, HARQ）的提出便是用來保證資料傳遞成功的機制。HARQ在IEEE 802.16-2004就已被提出，然而我們發現該HARQ機制在802.16j中是不具效率的，而且也並無法確保QoS（Quality of Service）的要求。在本論文中我們改善Chen[4]所提出的Dynamic Pre-allocation HARQ（DP-HARQ）機制，藉由考慮slot分配不足及封包發生非連續錯誤時造成延遲時間增加等問題，並加入具服務品質感知（QoS aware）的機制，以降低整體延遲時間（delay）並能有效提高吞吐量（throughput）。最後，我們以具二個hop以上的模擬環境，證明我們所提出的方法優於802.16j的HARQ機制及Chen[4]的方法。 / Mobile Multihop Relay (MMR) had already been defined in IEEE 802.16 network. The major purpose of MMR is to efficiently extend the coverage of a base station and to solve the shadow fading problem. The Relay Station (RS) defined in IEEE 802.16j is thus proposed to fulfill these goals. Because of the MMR Relay Station, we need more channels to transmit packets. However we cannot guarantee that all chaneels are in good condtion, there might be a high probability of failure transmission. The Hybrid Automatically Repeat reQuest (HARQ) mechanism is therefor proposed to ensure the successful transmission. The HARQ proposed in IEEE 802.16-2004 is not sufficient in 802.16j. Besides it can not help to meet QoS (Quality of Service) requirements. In this reserch we improve Chen’s [4] Dynamic Pre-allocation HARQ (DP-HARQ) mechanism by considering some problems like lack of slot allocation and packet transmission failure with non-continuous error, etc. We add the QoS aware mechanism to reduce the overall delay time and improve the throughput effectively. Finally, we simulate three hops environment and show that our method outperforms both the standard IEEE 802.16j the HARQ mechanism and Chen’s [4] method.

<p>We are very thirsty in terms of everything to fulfil our needs in a sophisticated way, and this leads me choose the so called master thesis titled “Multihop Concept in Cellular Systems”.</p><p>This thesis introduces an approach towards the integration of relaying or multihop scheme in the next generation of cellular networks. In a multihop cellular architecture, the users send their data to the base station via relay station or with direct communication to the base station. These relay stations can either be the nomadic, fixed at specific location or users’ mobile station (i.e. mobile relay station). The main objective of this paper is to compare the difference between the relaying network architecture with different channel bandwidth as well as their performance gain. For this we integrate the relay station into conventional cellular networks using IEEE 802.16j (One of the standard introduced relay station concept in WiMAX) OFDMA (Orthogonal Frequency Division Multiple Access is a transmission technique that is based on many orthogonal subchannels (set of carriers) that transmits simultaneously). The results show that under certain conditions the throughput and coverage of the system has been increased with the introduction of the relay station in to cellular base station zone.</p>

IEEE 802.16e ¡]also known as Mobile WiMAX¡^ is currently the international MAC ¡]medium access control¡^ standard for wireless metropolitan area networks. To enhance the network throughput and extend the coverage of base station, IEEE then defined the 802.16j standard. Clearly, one of the popular applications for WiMAX is the multicast service. On the other hand, the design of power saving technologies is important since mobile stations are often powered by batteries. In this thesis, we study the maximum energy-efficient multicast scheduling ¡]MEMS¡^ problem for an IEEE 802.16j network with transparent mode. Specifically, the base station should determine how to schedule the multicast data in a multicast superframe such that the multicast energy efficiency of network is maximal. We first prove that the MEMS problem is NP-complete. Then on the basis of SMBC-AMC, we propose its variant, called SMBC-relay, to solve this problem. However, in SMBC-relay, the base station may send the same multicast data several times, wasting the scarce bandwidth. Hence we we propose a genetic algorithm-based multicast scheduling algorithm, called GAMS. One of the key features of GAMS is that the base station can control when to terminate the algorithm by stopping the evolution at any time. Simulation results show that GAMS significantly outperforms SMBC-relay in terms of multicast energy efficiency.

WiMAX is one of the rising communications technology which enables last mile broadband mobile wireless Internet connectivity. IEEE Std 802.16-2009 is the last accepted standard which targets mobile and fixed wireless broadband access. The standard defines two types of stations which are base and mobile stations. A base station has a wired connection to backhaul network and gives broadband wireless service to mobile stations. IEEE 802.16j standard which is an amendment to IEEE 802.16, introduces Multihop Relaying for increasing coverage and throughput. Deployment of relay stations, where the backbone network does not exist, is a cost effective solution. Two modes of operations are defined for relay station: transparent mode and non-transparent mode. Relays in transparent mode, are deployed for improving signal quality, so that mobile stations can use relay link for increasing throughput. In non-transparent mode, relays can send management packets, so that mobile stations, which are not in the direct reach of a base station, can connect to network through relay stations. In domain specific networks main data traffic is caused by the communication between subscribers in same region. In this thesis shortcut routing scheme is proposed as sending packets to destination directly through relay station for data traffic between two subscribers with a common relay. With shortcut routing, network throughput is increased by preventing links at higher layer in topology from becoming bottleneck. Moreover, by traversing fewer hops, latency decreases. We also propose traffic aware path selection method, where a path will more.

We are very thirsty in terms of everything to fulfil our needs in a sophisticated way, and this leads me choose the so called master thesis titled “Multihop Concept in Cellular Systems”. This thesis introduces an approach towards the integration of relaying or multihop scheme in the next generation of cellular networks. In a multihop cellular architecture, the users send their data to the base station via relay station or with direct communication to the base station. These relay stations can either be the nomadic, fixed at specific location or users’ mobile station (i.e. mobile relay station). The main objective of this paper is to compare the difference between the relaying network architecture with different channel bandwidth as well as their performance gain. For this we integrate the relay station into conventional cellular networks using IEEE 802.16j (One of the standard introduced relay station concept in WiMAX) OFDMA (Orthogonal Frequency Division Multiple Access is a transmission technique that is based on many orthogonal subchannels (set of carriers) that transmits simultaneously). The results show that under certain conditions the throughput and coverage of the system has been increased with the introduction of the relay station in to cellular base station zone.

Wireless multi-hop relay systems are the newest amendment to the IEEE 802.16 standard for local and metropolitan area networks, else known as WiMAX. Relay systems come in different flavours, based on their capabilities and have the potential to offer many advantages over the single-hop technology. Upcoming broadband wireless technologies, that utilize multi-hop relays, need good network planning and design in order to achieve their full potential. There are two main types of multi-hop relay stations: transparent, which are not able to transmit control information and non-transparent, which have the capability to transmit such information. This study focuses mainly on non-transparent relay stations due to their complexity and ability to operate in a more than two hop environment. Currently, the latest IEEE amendment provides two different frame structures − single and multi-frame − for utilization in multi-hop relay networks, to allocate bandwidth. The purpose of this thesis is to evaluate the two proposed frame structures, in various network scenarios in terms of delay, throughput, rate, and user capacity. In addition, we will discuss some of the issues that need to be considered to cost effectively plan and design a multi-hop relay network. The evaluation methodology that we utilize is in accordance with the Multi-hop Relay System Evaluation Methodology developed by the IEEE 802.16 Broadband Wireless Access Working Group. To evaluate the above frame structures we developed an evaluation model for use in the network simulator 2 (ns2) from University of California Berkeley, by modifying the light WiMAX (LWX) add-on from Taiwan University. Unlike the original LWX module, which supports only transparent relay configurations, our module supports both multi-frame and single frame structures, as well as non-transparent multi-hop relay environments. To our knowledge there is no previous work, which analyzes the performance of the single frame and multi-frame system in multi-hope relay environments using the guidelines from the latest amendment to the standard (IEEE 802.16j-2009). Moreover, there is no publicly available software that will enable the study of such performance. The resulting source code of our work has been made publicly available and can be obtained from our website. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-09-09 23:55:00.995