A methodology for information and capacity analysis of broadband wireless access systems

In IEEE 802.16 broadband wireless access (BWA) systems, the uplink performance is affected by the size of the contention period in the subframe since the bandwidth request (BR) messages are sent during the period and the bandwidth for each service can be allocated only when the BR messages are accepted. In this paper, we develop a cross-layer analytical model for designing the optimal size of the contention period in IEEE 802.16 BWA systems with various classes of services. The model is validated by Monte Carlo simulation, and the results show that our cross-layer design provides a good scheme for determining the contention period size when the system performance is optimized.

A fair and efficient service flow management architecture for IEEE802.16 broadband wireless access (BWA) systems is proposed for TDD mode. Compared with the traditional fixed bandwidth allocation, the proposed architecture adjusts uplink and downlink bandwidth dynamically to achieve higher throughput for unbalanced traffic. A deficit fair priority queue scheduling algorithm is deployed to serve different types of service flows in both uplink and downlink, which provides more fairness to the system. Simulation results show the proposed architecture can meet the QoS requirement in terms of bandwidth and fairness for all types of traffic.

Relay is considered as a method to ensure capacity and coverage in the broadband wireless access (BWA) system. This paper proposes a type of MAC layer simulator architecture for the relay enhanced BWA networks, and then addresses the issue on the network topology when relay is introduced. Furthermore, downlink co-operative communication in such relay scenario is discussed on. The results show that the proposed relay enhanced BWA system outperforms the single-hop one on spectrum efficiency.

Broadband wireless access (BWA) systems offer a solution for broadband access and high data rate transmission of multimedia services with distinct quality-of-service (QoS) requirements through a wireless medium, IEEE 802.16 standard specifies the PHY and MAC layers for BWA systems. However, in spite of including the possibility for QoS support, the standard does not define how to schedule different types of traffic. This article propose a new MAC protocol for BWA systems that incorporates a traffic scheduling mechanism based on messages and/or stations priorities. An analytical model to evaluate the performance of the proposed protocol is also developed and results obtained for the messages waiting times of different traffic classes are presented.

In order to satisfy the demand of future Broadband Wireless Access (BWA) with high mobility, high data rate and low cost, Tsinghua University proposes a novel BWA system named BRadio with independent intellectual property rights. This paper describes the BRadio system from the aspects of physical layer technologies, Medium Access Control (MAC), networking methods, and services. The physical layer technologies focus on Time domain and Frequency domain United Orthogonal Frequency Division Multiple Access (TFU-OFDMA), Time domain and Frequency domain United Single Carrier Modulation time division multiple Access (TFU-SCMA), Interleave Division Multiple Access (IDMA), and Multiple Input Multiple Output (MIMO). In MAC layer we describe several new functionalities in BRadio system. The networking methods of BRadio are divided into networking independently and networking with the existing networks. BRadio can support various services, among which, the Personal Media Service (PMS) is presented in detail. Relying on the technical superiority of its high data rate, high mobility and low cost, as well as its flexible networking and comprehensive service platform, BRadio has become a potential technical solution for BWA.

Coverage study for broadband wireless systems using link adaptation and diversity combining techniques

In the gigabit millimeter-wave broadband wireless access (Gb MMW BWA) system. Quality of MMW is strongly affected by rainfall hence the MMW link may fall down in the case of heavy rainfall. The making of route detour to avoid that heavy rain zone is expected to improve the quality. For that matter, however, it may be not sufficient to provide the high-traffic demands. Therefore, in this paper, we propose the QoS-based adaptive modulation scheme to compensate for rain attenuation, and thus to improve the spectrum efficiency of system.

For the broadband wireless access system of the railway system, because the trains move forward on the railroad in a fixed direction under a regular path, the mobile stations on the railway trains can only choose the approaching neighboring base stations as unique target base station candidates. This is different from the typical broadband wireless access systems. Using the IEEE 802.16e handover algorithm, a simplified, modified handover procedure is proposed to reduce the memory consumption of paused data buffer during the cell re-selection process and shorten the handover operation time during the handover process.

Single carrier transmission with frequency domain equalization (SC/FDE) provides a serious alternative to orthogonal frequency division multiplexing (OFDM) for broadband wireless access (BWA) systems as well as for W-LAN's. In this work we consider low complexity Turbo-like decision feedback equalization for conventional block wise SC/FDE. The proposed scheme accomplishes the efficiency of ideal decision feedback equalization. Simulation results show a remarkable performance increase for large signal constellations and highly frequency selective multipath channels.

Next generation mobile networks are expected to provide seamless personal mobile communication and quality of service (QoS). Fair, class based service and Lossless handoff are the key issues for providing the QoS. This paper proposes a scheduling mechanism for providing QoS in mobile networks, which exploit IP as a transport technology for transferring data between base stations of Broadband Wireless Access Systems at the radio layer. In order to improve QoS a new scheduling algorithm is performed at both IP and radio layer, which exploit handoff priority scheduling principles and takes into account buffer occupancy and channel conditions. The fairness among the users of different classes is also accounted Performance results obtained by computer simulation show that, by exploiting the new scheduling algorithm, the system is able to provide low handoff packet dropping rate, low packet forwarding rate and low packet delay.

In the last few years, the term “quality of service” has become increasingly synonymous with digital cellular networks and has greatly influenced the way we manage network traffic. The IEEE 802.16 standard is a broadband wireless access system that enables high speed data transfer over large distances. It is one of the standards that meet the IMT-Advanced specifications. It also incorporates a quality of service framework to provide quality of service to both realtime and non-realtime multimedia applications. One of the critical contributions of a QoS framework is efficient scheduling of network traffic. This paper dilates on a two-level scheduling algorithm for base station uplink scheduler to provide quality of service to various classes of traffic. The proposed algorithm ensures efficient and fair multimedia transmission. We also deliberated on a video transmission framework based on the proposed algorithm. The performance of two-level scheduling algorithm has been extensively analyzed through simulations and the results have effectively established the efficacy of the proposed algorithm. The results reveal that the the proposed algorithm is able to fairly and efficiently schedule network traffic while ensuring quality of service for all classes of traffic.

We have built a wireless mesh network testbed, which is tolerant of disaster and aim to resolve a digital divide issue in rural mountain areas. This testbed is located in two areas and has total 22 nodes which are installed on the power poles in these areas. Two areas are connected to a control server at Niigata university with broadband wireless access systems using 5 GHz band via a gate way node at the local-government office, which is located at the center of two areas. Each node has two wireless LAN interfaces with IEEE 802.11b/g and a wireless LAN access point. We measure the throughput and the packet transmission successful ratio of links in our testbed. Moreover, we investigate the technical issues to manage and operate the mesh network in the rural mountain areas.

This paper describes a broadband local access system at 28 GHz. In the United States these systems are generally referred to as Local Multipoint Distribution Service or LMDS. The FCC bandplan is discussed and a proposed utilization of the spectrum is presented. The architecture for an LMDS system is described along with link budgets and capacity estimates.

Bandwidth allocation and admission control scheme based on Nash bargaining solution for WiMAX systems

This paper indicates the space time block code provides transmit diversity in wireless fading channel during the STBC-OFDM system. OFDM is enforced in broadband wireless access systems as the way to beat wireless channel impairments and to enhance and breadth potency. This research is to analyze the performance of non STBC-OFDM system and STBC-OFDM system. The performance has been evaluated for construction modulation (QAM) technique for orthogonal frequency division multiplexing (OFDM) systems using multiple transmit diversity antenna system in the channel. Conjointly the equation of SNR and BER has been derived for 16-QAM for multiple transmit and receive antenna for STBC-OFDM system by considering the have an effect on of Inter-symbol interference (ISI), phase noise and temporal arrangement noise in Raleigh fading channel.