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Abstract-The latest mobile WiMAX standard promises to deliver high data rates over extensive areas and to large user densities. More specifically, data rates are expected to exceed those of conventional cellular technologies. The IEEE 802.16e Wi-MAX standard enables the deployment of metropolitan area networks to mobile terminals in non-line-of-sight radio environments. Current concerns include leveraging high data rates, increasing area coverage, and competing with beyond 3G networks. Based on the IEEE 802.16e wirelessMAN-OFDMA (Orthogonal Frequency Division Multiple Access) physical (PHY) layer air-interface, this paper presents a physical layer study of MIMO enabled mobile WiMAX in an urban environment. The radio channels are based on those developed in the European Union IST-WINNER project. Results are given in terms of system throughput and outage probability with and without relays for a range of SISO, MISO and MIMO architectures. Results show that satisfactory performance cannot be achieved in macrocells unless radio relays are used in combination with MIMO-STBC.

The challenge at millimeter-wave frequencies is that the propagation characteristics approximates to that of light. In a non line-of-sight scenario, when even the mobile station (MS) is near the base station, the attenuation may be tens of dBs due to shadowing and obstructions. Increasing the number of base stations reduces such effects but at the expense of cost and complexity. An attractive method to mitigate such shadowing effects is to use dedicated active or passive relay stations. Proposed here is a network infrastructure in the form of a 3D pyramid. It consists of a single access point with four (but not restricted to) active relays operating in parallel in a medium sized room of 400m 2. Simulation is performed in a sophisticated 3D ray tracing tool. Human shadowing densities of 1 person/400m 2 up to 1 person/1m 2 are set to test the robustness of such a system. Results show that comparing to a normal system with just a single access point either mounted on the ceiling or at the same level as a MS; the pyramid relaying system provides superior coverage and capacity.

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