This chapter presents a concept and the related performance evaluation for a wireless broadband system based on fixed relay stations acting as wireless bridges. The system is equally well-suited for both dense populated areas and wide-area coverage as an overlay to cellular radio systems. A short introduction is given to the general topic of fixed relaying. The proposed extension to a Medium Access Control-frame based access protocol like IEEE802.1 I e, 802.15.3, 802.16a and HIPERLAN2 is outlined. A possible deployment scenario is introduced and the simulative traffic performance in a Manhattan-like dense urban environment and a wide-area open-space environment is presented. It is established that the fixed relaying concept is well suited to substantially contribute to provide high capacity cellular broadband radio coverage in future (NG) cellular wireless broadband systems.

This work presents a concept and the related analysis of the traffic performance for a wireless broadband system based on fixed relay stations acting as wireless bridges. The analysis focuses on the important performance indicators end-to-end throughput and delay, taking into account the effects of an automated repeat request protocol. An extension to a MAC frame based access protocol like IEEE 802.11e, 802.15.3, 802.16a, and HIPERLAN2 is outlined and taken as basis for the calculations.The system is intended for both dense populated areas as an overlay to cellular radio systems and to provide wide-area broadband coverage. The two possible deployment scenarios for both dense urban and wide-area environments are introduced. Analytical and validating simulation results are shown, proving the suitability of the proposed concept for both of the mentioned scenarios.It is established that the fixed relaying concept is well suited to substantially contribute to provide high capacity cellular broadband radio coverage in next generation (NG) cellular wireless broadband systems.

This contribution highlights the possibilities and service characteristics for a cost and time efficient roll out for public wireless local area networks providing wide coverage in urban areas. The HiperLAN/2 (H/2) multi hop concept is based on intermediate relay stations. This eliminates the need for intensive cabling, reducing the costs. The H/2 multi hop concept introduces a new element called forwarding mobile terminal (FMT) to the H/2 world. The FMT is a modified H/2 mobile terminal which only needs different software, but no additional transceiver. In city scenarios the forwarding concept allows a fast roll-out while limiting the cabling cost and providing a reasonable user service in a large service area.

A concept is presented that introduces a new element called forwarding mobile terminal (FMT) to the HIPERLAN/2 (H/2) world. The FMT is designed to provide users in uncovered areas with access to the fixed Internet by providing an intermediate hop. The FMT is introduced in a way that it is backward compatible to existing H/2 equipment. The FMT is a modified H/2 mobile terminal which needs different software, but no additional transceiver. The concept is evolved for the H/2 link layers and signalling flows, furthermore future possible enhancements are presented.

A new approach to extend the communication range of standard HiperLAN/2 (H/2) cells is presented. The basic idea is to use a relay in the time domain that supports terminals outside the range of a H/2 access point. The concept presented employs a novel MAC sub-frame structure generated by a new H/2 element called Forward Mobile Terminal (FMT) that serves out-of-range terminals. We present an analysis of the impact of FMTs on the achieved Quality of Service (QoS) for the H/2 system. Further, the possible service area extension is analysed.

Wireless local area networks (WLANs) designed as wireless ATM systems to extend the services of fixed ATM networks to mobile users appear best suited to provide a guaranteed quality of service (QoS) for wireless IP networks. HiperLAN/2 is an ETSI/BRAN standard providing convergence layers for both IP and ATM classes of service. Besides a description of HiperLAN/2 and its Home Environment Extension, the performance for IP traffic flows is presented from analysis and from simulating a prototype implementation. Co-existence with the IEEE 802.11a WLAN is discussed and the ability of HiperLAN/2 to guarantee QoS even when coexisting is analyzed. Ad hoc networking of HiperLAN/2 is analyzed and two possible extensions of the system are introduced and their performance evaluated, namely, adaptive antennas and wireless base stations.

A concept is presented which introduces a new element called forwarding mobile terminal (FMT) to the HIPERLAN/2 (H/2) world. The FMT is designed to provide users in uncovered areas with access to a fixed network by providing an intermediate hop. The FMT is introduced in a way that it is backward compatible with existing H/2 equipment. The FMT is a modified H/2 mobile terminal which needs different software, but no additional transceiver. The concept is evolved for the H/2 link layers and analysed in its implication on the quality of service provided to the users.

In this paper the cellular aspects of a concept will be investigated that introduces a new element called forwarding mobile terminal (FMT) to the HiperLAN/2 (H/2) world. The FMT is designed to extend the area of an H/2 access point and provide users in uncovered areas with access to the fixed Internet by providing an intermediate hop. The FMT is a modified H/2 mobile terminal which only needs different software, but no additional transceiver. The contribution shows the behaviour of the above concept in different cellular environments regarding the interference situation and the effects onto the users. The concept is especially advantageous for environments where high attenuation by walls is expected. In city scenarios the forwarding concept allows a fast system roll-out while limiting the cabling cost and providing a reasonable user service in a large service area.

The BMBF founded project COVERAGE investigates broadband access to the IP core-net in public or semipublic hot spot scenarios for mobile users. The basis for our investigations are OFDM-systems (Orthogonal Frequency Division Multiplex) like H/2 (HiperLAN/2) or IEEE802.11a which provide data-rates up to 54 Mbit/s. Main topic of COVERAGE are multihop networks as a means to increase the access area of H/2 radio cells. Unfortunately the performance of multihop networks with respect to throughput decreases rapidly with the number of so called EPs (Extension Point) as intermediate hop devices. One reason is the protocol overhead of H/2. For single APs this protocol overhead can be accepted, while in a multihop network this overhead is required once for each additional EP. Here we propose a suitable combination of a DLC protocol with sector antennas and SFN (Single Frequency Network) concepts, which reduces the overall protocol overhead.

The interconnection of a wireless ATM (WATM) system with the fixed B-ISDN is a demanding task in order to bring B-ISDN services to mobile users. In this paper we present the network protocols as developed in the ACTS SAMBA project and realised in its demonstrator. The procedures for mobility, radio resource management and access to the B-ISDN will be discussed in detail. A protocol for network handover required in addition for large WATM systems will be presented and analysed

This paper provides a comprehensive overview of the development of performance critical communication systems such as HiperLAN/2(H/2), the corresponding timing concepts for H/2 Mobile Terminal (MT) and Access Point (AP) protocols and the protocol implementation in a hard real time system. Moreover, the paper introduces some concepts to optimize the processing power sharing among real time and non real time tasks.