This paper introduces an error resilient implementation of the matching pursuits algorithm for video coding. The video bitstream is transmitted using the simulated Bluetooth air interface standard, which recommends ARQ as a means of overcoming channel errors in data packets. This may be unsuitable for real time and broadcast applications. Therefore, a modi3ed receiver is proposed in this paper, which does not request a retransmission of erroneous packets, but instead passes them to the video decoder to exploit error resilience. This strategy is shown to be superior to a standard compliant system if ARQ cannot be applied. This work confirms that wireless communication standards should support a transparent mode for video applications.

Coded Orthogonal Frequency Division Multiplexing (COFDM) is currently specified in all three of the world's 5 GHz wireless LAN standards (Hiperlan/2, IEEE 802.11a and MMAC HiSWANa). This technology was chosen due to its robustness at high data rates in a frequency selective multipath channel. Each standard operates using adaptive sub-band Quadrate Amplitude Modulation (QAM) and offers a maximum data rate of 54 Mbits/s over a 20 MHz channel. This paper describes a real-time DSP implementation of an asynchronous OFDM based high speed WLAN system. The software reconfigurable OFDM based platform is developed around the Texas Instruments fixed point TMS320C6201 DSP. The physical layer DSP performance is evaluated and compared for an indoor channel against floating point C++ based simulations. Data throughput and complexity estimates are generated from the resulting hardware platform. Finally, a video based communications application is developed to operate over the demonstrator. Results indicate that the fixed point DSP solution can operate within 0.5 dB of the floating point simulation in an AWGN channel. For the indoor fading channel, an implementation loss of around 2.5 dB was observed.

ABSTRACT

In this paper, the average Area Spectral Efficiency (ASE) in bits/Sec/Hz/Km2 of a variable transmission rate, high capacity cellular communication system is studied in a correlated shadowed environment. The effect on average ASE of the normalised reuse distance, shadowing variance, correlation between radio signals, coverage radius and cell sectorization is investigated by computer simulations. It is shown mathematically that the average ASE of an interference limited mobile radio channel increases with the increased shadowing variance. Downlink simulation results indicate that, the increase in shadowing correlation between the desired and the sum of the undesired signals reduces the average ASE whereas mutual correlation between individual interfering signals increases the average ASE. The variation of cell size on average ASE is also investigated. The results suggest small cell sizes in heavily shadowed areas are well suited for highspeed variable data rate transmissions.

-This paper begins by highlighting key features of the Bluetooth baseband standard. Software simulated results for the transmission of symmetric asynchronous data link (ACL) packets are used to discuss bit rate capabilities of various timebounded and non-time bounded Bluetooth enabled consumer electronic devices. The investigation considers Bluetooth data medium (DM) and data high (DH) packet types. To meet the bit rate needs of future consumer electronic devices, BPSK, QPSK and 16-QAM are proposed as possible enhancements to the current GFSK modulation. The relative merits and demerits of using coherent modulation and linear receive architectures versus non-linear differential detection are discussed. Although adding considerably to the unit cost, the former is shown to significantly improve radio sensitivity. Results indicate that although the use of QAM modulation facilitates higher data rates, PSK schemes are more likely candidates for a low cost, high data rate Bluetooth extension due to the fact that they have less demanding hardware requirements.