In this thesis we investigate the performance of spatial reuse in wireless networks. More specifically, we investigate the performance of location-based spatial reuse built upon the identification of links in the network that form Collision-Free Sets (CFSs). We develop algorithms that efficiently find such CFSs. The main focus of this thesis is the application of our CFS-based algorithms to emerging WiMAX (Worldwide Interoperability for Microwave Access) networks. However, we will also apply our CFS-based algorithms to smaller scale networks, as well as to the issue of QoS routing. This thesis makes several contributions. We first show how CFSs can be found within polynomial time in small scale wireless networks. We then probe how CFSs can be used to enhance network efficiency when location is available. We also explore how CFS determination is affected by location error, determining what level of location error renders the use of CFSs ineffective. In this context, we discuss the density of access points required to ensure CFS-based spatial reuse remains effective. We then focus on the use of CFSs in emerging multihop WiMAX networks, showing in detail how enhanced spatial reuse is delivered. The spatial reuse gains are probed both in the presence of realistic channel conditions and realistic location errors. Within the context of the IEEE 802.16 standard we show how CFSs can enhance, by factors of two, the VoIP capacity of multihop WiMAX networks. We also discuss how our CFS algorithms can be applied to other ongoing efforts aimed at improving VoIP capacity in WiMAX networks. Finally, an application of our CFS algorithms in the context of QoS routing is studied. Specifically, we develop a two-hop QoS routing protocol that guarantees QoS specifications by securing higher bandwidth for the chosen routes.

By envisioning that the future broadband access networks have to support many bandwidth consuming applications, such as VoIP, IPTV, VoD, and HDTV, the integration of WiMAX and EPON networks have been taken as one of the most promising network architecture due to numerous advantages in terms of cost-effectiveness, massive-bandwidth provisioning, Ethernet-based technology, reliable transmissions, and QoS guarantee. Under the EPON-WiMAX integration, the development of a scheduling algorithm that could be channel-aware and queue-aware will be a great plus on top of the numerous merits and flexibility in such an integrated architecture. In this thesis, a novel two-level scheduling algorithm for the uplink transmission are proposed by using the principle of proportional fairness for the transmissions from SSs over the WiMAX channels, while a centralized algorithm at the OLT for the EPON uplink from different WiMAX-ONUs. The scheduler at the OLT receives a Report message from each WiMAX-ONU, which contains the average channel condition per cell, queues length, and head-of-line (HOL) delay for rtPS traffic. The EPON data frame is then scheduled based on these Report messages. Numerical results show that the proposed scheme could satisfy the end-to-end real-time QoS requirements. In addition, the centralized scheduler at the OLT can achieve high throughput in presence of traffic load variation.

In recent years, mobile hotspots have been getting much attention of the researchers. They are implemented on moving platforms. Research interests in mobile hotspots are motivated by the demand of seamless mobility. The IEEE 802.16e or mobile WiMAX opens a new door of possibility of mobile broadband. It provides extended mobility support and larger cell coverage. In this thesis we propose a simple link adaptation (LA) algorithm for the mobile hotspots, which are supported by (mobile) WiMAX network. The role of link adaptation (LA) is very important because it controls the physical layer throughput. Therefore, all the higher layers are affected by LA. The main function of an LA algorithm is to select an appropriate burst profile. We consider downlink scenarios of WiMAX supported mobile hotspot. We formulate a discrete value optimization problem for LA, whose objective is throughput maximization. We choose forward error correction block rate (FBER) as constraint. The proposed LA algorithm comes as solution of the optimization problem. The proposed algorithm adapt with MAC layer performance. We develop a downlink channel estimation technique, propose an intra subchannel power allocation strategy, and propose an adaptive automatic repeat request (ARQ) mechanism as part of LA technique. We estimate SNR using channel estimation and intra subchannel power allocation. Then the estimated SNR is adjusted based on velocity of mobile hotspot. Adjusted SNR is used to select optimum burst profile. The performances of the proposed LA algorithm are evaluated through numerical results obtained from link level simulations. According to numerical results, the proposed LA algorithm is able to maintain a certain level quality of service (QoS).

By envisioning that the future broadband access networks have to support many bandwidth consuming applications, such as VoIP, IPTV, VoD, and HDTV, the integration of WiMAX and EPON networks have been taken as one of the most promising network architecture due to numerous advantages in terms of cost-effectiveness, massive-bandwidth provisioning, Ethernet-based technology, reliable transmissions, and QoS guarantee. Under the EPON-WiMAX integration, the development of a scheduling algorithm that could be channel-aware and queue-aware will be a great plus on top of the numerous merits and flexibility in such an integrated architecture. In this thesis, a novel two-level scheduling algorithm for the uplink transmission are proposed by using the principle of proportional fairness for the transmissions from SSs over the WiMAX channels, while a centralized algorithm at the OLT for the EPON uplink from different WiMAX-ONUs. The scheduler at the OLT receives a Report message from each WiMAX-ONU, which contains the average channel condition per cell, queues length, and head-of-line (HOL) delay for rtPS traffic. The EPON data frame is then scheduled based on these Report messages. Numerical results show that the proposed scheme could satisfy the end-to-end real-time QoS requirements. In addition, the centralized scheduler at the OLT can achieve high throughput in presence of traffic load variation.

In recent years, mobile hotspots have been getting much attention of the researchers. They are implemented on moving platforms. Research interests in mobile hotspots are motivated by the demand of seamless mobility. The IEEE 802.16e or mobile WiMAX opens a new door of possibility of mobile broadband. It provides extended mobility support and larger cell coverage. In this thesis we propose a simple link adaptation (LA) algorithm for the mobile hotspots, which are supported by (mobile) WiMAX network. The role of link adaptation (LA) is very important because it controls the physical layer throughput. Therefore, all the higher layers are affected by LA. The main function of an LA algorithm is to select an appropriate burst profile. We consider downlink scenarios of WiMAX supported mobile hotspot. We formulate a discrete value optimization problem for LA, whose objective is throughput maximization. We choose forward error correction block rate (FBER) as constraint. The proposed LA algorithm comes as solution of the optimization problem. The proposed algorithm adapt with MAC layer performance. We develop a downlink channel estimation technique, propose an intra subchannel power allocation strategy, and propose an adaptive automatic repeat request (ARQ) mechanism as part of LA technique. We estimate SNR using channel estimation and intra subchannel power allocation. Then the estimated SNR is adjusted based on velocity of mobile hotspot. Adjusted SNR is used to select optimum burst profile. The performances of the proposed LA algorithm are evaluated through numerical results obtained from link level simulations. According to numerical results, the proposed LA algorithm is able to maintain a certain level quality of service (QoS).

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Abstract Competition is the leading role for traditional concept, telecommunication industry also take competition as the thinking aspect in early days. In the time of digit convergence, competition is not only found in local but in global and technology is not belonged to single company any more. The thinking of competition has not coped with the market in the future and should take the thinking of co-opetition for the strategy development. The technology of 3rd Generation mobile communication can bring telecommunication industry new opportunities by providing customers the multiple services with higher speed such as data transmission, mobile business and multimedia A/V. This research discusses the strategy management of the industry for mobile communication in the time of digit convergence by studies of competitive strategy, value-chain of industry, co-opetition theory and analysis of industry status. After summarizing the related documents, literatures and the result of interviewing the specialists in this field, we have some conclusions listed as below: 1.To have the synergy, the technology between mobile wideband and wireless wideband must operate complementarily. 2.To adapt the uncertainty of digit convergence, the service providers of mobile communication should develop co-opetition strategy. 3.Should actively take the predomination for the technology standard of the industry. 4.The thinking of building the network for mobile communication should focus on the total solution of long-term evolution for network equipments. 5.The strategy of differential service is the essential strategy for the tendency of integrating fixed mobile convergence.

Many different wireless technologies have increased the demand of accessing Internet resources through wireless networks. One of the most popular applications is watching multimedia streaming over wireless. However, when a user is roaming in a heterogeneous network, he needs to acquire adequate bandwidth from different wireless access points. In this Thesis, we propose a Mobile-IP based vertical handoff scheme in a heterogeneous WiMAX and WLAN. When a mobile node is in the overlapped area of WiMAX and WLAN, it may have to execute the vertical handoff based on the received average signal strength, the transmitting queue length of network interface, and the available network bandwidth. Our goal is to reduce the influences of RTP-based video streaming when the network is congested and when a mobile node executes the vertical handoff in the heterogeneous network. We implement the Dynamic Mobile-IP based vertical handoff on Linux platform by modifying handoff decisions between WiMAX and WLAN. The above-mentioned performance parameters are implemented as modules on Linux platform. At last, we prove that our scheme can effectively improve packet loss ratio and system processing ratio. As a result, the frame mosaic phenomenon and frame slow-playing phenomenon in RTP-based video streaming can be significantly improved.

In this thesis, we consider a network environment which consists of wired Internet and a wireless broadband network (WiMAX); data from wired or wireless network are all conveyed through WiMAX links to its destination. In order to promise the quality of real-time traffic and allow more transmission opportunity for other traffic types, we propose an Adaptive Bandwidth Allocation (ABA) algorithm for BS to adequately allocate bandwidth. Our ABA algorithm would first reserve required minimum bandwidth for high-priority traffic, such as video streaming. By allocating minimum bandwidth to real-time traffic, the delay time constraint can be satisfied. Other traffic types, such as non-real-time, which have no real-time requirement, may gain extra bandwidth to improve their throughput. For best-effort traffic, the remaining bandwidth can be used to avoid any possible starvation. We build four-dimension Markov chains to evaluate the performance of the proposed ABA algorithm. In the analytical model, we first divide transmission on WiMAX into upload and download phases, and analyze the ABA performance by using Poisson process to generate traffic. At last, by comparing to a previous work, we observe the impacts of different traffic parameters on WiMAX network performance in terms of average delay time, average throughput, and average packet-drop ratio.

WiMAX is a new mobile technology which provides high bandwidth and VoIP service. Therefore, WiMAX will bring effects to 3G telecom market. It is important that 3G telecom how to face WiMAX effects and WiMAX telecom how to enter the telecom market. Because WiMAX does not operate popularly and literatures usually only compare technology between WiMAX and 3G, this research discusses pricing strategy of the WiMAX and 3G. This study discusses WiMAX and 3G based on MEC Model and Customer Differentiation Matrix, and uses price and platform of the MEC Model and customer valuation and customer need of the Customer Differentiation Matrix to discuss strategic position. This research uses case study to interview executive managers of the WiMAX and 3G telecoms. According to interview results and secondary data, this study concludes telecom strategic positions. These results: (1) voice service will become mass market; (2) mobile value-added service will become important strategy; (3) WiMAX telecom will enter telecom market quickly; (4) WiMAX is not only a competitive role but also a complementary role; (5) mobile telecom will become personalized service. This conclusion discusses WiMAX and 3G positions according to marketing strategy. The telecom market will create new pricing strategy due to market competition after WiMAX enters telecom market.