In simulations of the 1/spl times/EV-DO forward link, packet detection is frequently modeled in simulations by measuring the average signal-to-noise ratio received during a packet transmission, and comparing this to a pre-determined threshold to decide whether or not the packet was received in error. In this paper we consider an analytical treatment of such a model, and show that in some important cases it is possible to derive closed-form expressions for the forward link throughput and packet error rate (PER). The analytical approach can reveal improved methods for data rate selection by the access terminal, and be used for performance analysis and system optimization as an alternative to simulation.

We propose an adaptive data rate control method for mobile terminals in 1xEV-DO high data rate wireless networks. The method dynamically adjusts and maintains a signal-to-interference-plus-noise ratio (SINR) threshold and an "effective" data transmission rate for each discrete data rate option. After channel SINR measurement, the mobile terminal uses the SINR thresholds and effective transmission rates for the selection of the data rate option with highest possible throughput. At the same time, packet error rate is maintained at a target value by dynamically adjusting the thresholds according to the pattern of received frame errors. The algorithm allows the mobile terminal to adapt to changing channel conditions and it is very practical since it works based on a closed loop rate control mechanism. Simulations, for a wide range of channel conditions, show that the method maintains a target packet error rate and it results in higher throughput compared to other approaches where a fixed margin is added to AWGN thresholds. We also develop upper bounds on the achievable throughput for high mobile speeds and show that the results of the proposed method is very close to maximum achievable data rate.

One of the main improvements that the 1xEV-DO (IS-856) standard adds to the original HDR proposal is the hybrid automatic repeat request (H-ARQ) mechanism. The H-ARQ scheme combines error correction, error detection, soft packet combining and incremental redundancy. H-ARQ reduces the required forward link SINR and thereby improves overall system capacity, particularly in mobile environments. We present simulation results comparing the aggregate throughput of CDMA HDR systems with and without H-ARQ. We find that H-ARQ gives greatest gain at moderate to high mobile speeds and also at cell-edge locations, where the mean received Ec/Io is small. The addition of H-ARQ more than doubles the aggregate throughput for mobile speeds above 21 km/h.

We address the problem of power control for dedicated control channels (DCCHs) in IS-2000 CDMA networks during intervals of discontinuous transmission (DTX). A receiver must have the ability to distinguish between a bad traffic frame and a stoppage of transmission, if outer loop power control (OLPC) is to operate properly. We propose two new methods to facilitate the detection of a DTX interval. The first method uses measurements of the signal-to-noise ratios of the traffic channel and the power control sub-channel. The second uses explicit signaling between the transmitter and receiver. Simulations are used to assess the performance of the first method.

The quality of fast forward link power control in IS-2000 CDMA systems is examined by comparing it to ideal power control, for a one-path Rayleigh channel model. Closed form expressions are derived that relate average transmitted power and average received signal-to-noise ratio for ideal power control. Simulations are used to compare the power control achievable in a Radio Configuration 3 (RC3) IS-2000 system with that of ideal power control, for the case of a slowly moving (3 kmm) mobile. In this case, IS-2000 power control requires 4 dB more power than ideal power control for 1% frame error rate (FER), and 1.3 dB for an FER of 10%. The narrow margin for improvement at large FER targets makes it unlikely that substantial capacity gain can be achieved from improved power control in networks carrying mostly data traffic, since FER targets are likely to be higher for data than for voice.

The performance of a binary-quantized data-transition tracking loop symbol synchronizer operating in cochannel interference (CCI) and noise is examined for both binary phase-shift keying and quaternary phase-shift keying modulations. The CCI can be included in a previously known Markov chain model without increasing the number of states in the chain, but the cost of computing the transition probabilities increases exponentially with the number of interferers. It is shown that a first-order Markov model and simulation are in close agreement for some important applications. The effect of interferer epoch on the degradation caused by the interference is investigated and the degradations in performance caused by CCI and by Gaussian noise are compared.

This paper compares the performance of two transmit diversity schemes, orthogonal transmit diversity (OTD) and phase sweeping transmit diversity (PSTD), when utilized by the cdma2000 forward link. Each scheme is simulated for one- and two-path Rayleigh fading channels, and for a one-path Rician fading channel with different k-factors. For configurations employing a coding rate of 1/2 , it is shown that PSTD can significantly outperform OTD when the fading is Rayleigh distributed. For configurations using a coding rate of 1/3, the two methods provide similar performance under Rayleigh fading conditions. Under Rician fading conditions, OTD provides gain over PSTD for both code rates. The gain increases for higher k-factors.