In this paper, a multiple-input-multiple-output (MIMO) extension for a third-generation (3G) wireless system is described. The integration of MIMO concepts within the existing UMTS standard and the associated space-time RAKE receiver are explained. An analysis is followed by a description of an actual experimental MIMO transmitter and receiver architecture, both realized on digital signal processors (DSPs) and FPGAs within a precommercial OneBTS base station. It uses four transmit and four receive antennas to achieve downlink data rates up to 1 Mb/s per user with a spreading factor of 32 and the UMTS chip rate of 3.84 MHz. Furthermore, different MIMO detectors are evaluated, comparing their performance and complexity. System performance is evaluated through simulations and indoor over-the-air measurements. Capacity and bit-error rate measurement results are presented.

We consider an image transmission system consisting of set partitioning in hierarchical trees (SPIHT) wavelet-based source coding, and list Viterbi algorithm (LVA) channel coding using rate compatible punctured convolutional (RCPC) codes. Our goal is to minimize bandwidth usage while maintaining received image quality. We introduce an outage criterion for image transmission. A received image is considered to be in outage if its pixel values are not identical to the image transmitted. In order to reduce correlation in fading, an enhanced block interleaving scheme employing a subblock structure is proposed. Using RCPC codes, we devise a variable rate channel coding system based on the current channel state information. Combining enhanced interleaving and variable rate channel coding, we construct a method to select the highest rate RCPC code that satisfies the image outage criterion, thus balancing the requirements of high bandwidth efficiency and high image quality.

This paper proposes a packetized direct sequence code division multiple access (DS-CDMA) multimedia wireless communication system that allows for seamless interfacing to asynchronous transfer mode (ATM) broadband networks. The issue of reverse link power control is examined in the context of an indoor environment characterized by a slowly Rayleigh fading channel. Three algorithms are discussed: open loop, channel estimation, and closed loop power control. It is shown that closed loop power control with channel estimation achieves the best performance. The system capacity with perfect power control is calculated. The effect of power control imperfection on the capacity and received signal statistics is studied based on computer simulation. It is shown that actual cell capacity using a two-bit power control command is approximately 40% greater than that using a one-bit power control command at the expense of twice the feedback overhead.

This paper proposes a packetized direct sequence code division multiple access (DS-CDMA) system model that supports integrated voice and data traffic in a slowly Rayleigh fading environment and allows for seamless interfacing to an asynchronous transfer mode (ATM) broadband network. Forward error correction (FEC) coding and an automatic retransmission request (ARQ) protocol are applied to data packets. A queueing model is used for servicing data transmission requests. The reverse link power control utilizes a closed loop algorithm with channel estimation. A one-bit power control command is used for delay insensitive data packets and a two-bit command for delay sensitive voice packets. The cell capacity for data users is analyzed and is extended to include voice users by assigning a fixed number of DS-CDMA channels for data traffic and using all the remaining resources for voice traffic. It is shown that there is a linear relation between the capacity for data users and that for voice users.