Abstract-The simulation results are generated using a fully compliant 802.16e simulator and cover important aspects such as link adaptation, packet error rate and throughput. The theory is supported by experimental data captured in an urban microcell environment using a mobile WiMAX basestation. Predicted results are compared with measured data taken from a number of vehicular drive tests. Analysis shows that mobile WiMAX is able to achieve a street-level range of 300-2100m depending on the permitted EIRP level.
This paper presents a performance evaluation of a WiMAX system (802.16-2004) employing directional antennas in highly mobile applications. A WiMAX physical layer simulator is used together with an appropriate mobile channel model to perform the analysis. Results show that mobile performance is significantly improved when directional antennas are utilised at the mobile end of the link. These antennas reduce the resulting Doppler spread, which in turn increases the channel's coherence time. In a time varying channel, irreducible errors occur as a result of an aging channel estimate. The structure of the channel estimation pilots has a strong impact on performance. Analysis reveals that results are relatively insensitive to the shape of the Power Doppler Profile, but strongly related to the value of the Doppler spread.
Abstract-Demand for broadband services continues to grow. Conventional high-speed broadband solutions are based on wired-access technologies, such as digital subscriber line (DSL). This type of solution is difficult to deploy in remote areas, and furthermore it lacks support for terminal mobility. Broadband Wireless Access (BWA) offers a flexible and cost-effective solution to these problems. The WiMAX standard has emerged to harmonize the wide variety of different BWA technologies. The most recent WiMAX standard (802.16e) supports broadband applications to mobile terminals and laptops. This paper analyses the performance of a mobile WiMAX system operating in an urban microcell. As an extension to the basic SISO mode, a number of 2x2 MIMO extensions are analysed. Simulated packet error rate and throughput results are presented for each linkspeed. The paper highlights the trade-off between peak error-free throughput and robust operation at low SNR.
Abstract-This paper presents experimental results from a series of IEEE 802.11g studies to investigate the performance of vehicular to roadside wireless communications. In particular, two high-gain omni-directional antennas were used at the roadside access point, while high-gain omni-directional and directional antennas were compared for use on the vehicle. By employing high-gain antennas at both ends of the wireless link, the range of the WLAN network was dramatically improved. Moreover, the use of directional antennas in highly mobile applications allows communication at higher vehicle speeds (by reducing the Doppler spread) and longer ranges (by reducing delay spread and increasing the received power level). Results show that mobile performance is significantly improved, especially when directional antennas are utilised at the receiving end of the link. As a result, the amount of data that can be exchanged between a moving vehicle and a roadside access point is considerably increased. The use of WDS (Wireless Distribution System) is also investigated in this paper. The reported measurements form part of a larger campaign to compare WiFi, WiMAX and HSPA technologies for vehicular communications.
Abstract-In this paper, mobile WiMAX trials are analysed to investigate the vehicular down-link performance for a number of on-car antenna configurations. The directionality and optimum polarization of the vehicular antennas are shown to improve both the range and throughput of the system. These improvements are attributed to the additional directive gain, and the reduced multi-input multi-output spatial correlation that results from orthogonal polarization. The mobile-WiMAX trials cover an urban vehicular scenario using a 2x2 MIMO system configuration. Results show that the throughput can be doubled for a wide range of received SNR levels (via STBC or SM) when a pair of directional dual polarized antennas are used at the vehicle (compared to omni-directional devices).
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