Optimal rate control in wireless networks with fading channels

Abstract

A dynarnic programming optimization method is used to obtain the optimal rate control policy in a wireless network with fading channel. In a wireless network it is assumed that the base station is capable of transceiving data packets at two rates, either Rh or RI (Rh > R1). An optimal policy is derived which jointly minimizes the transmission delay and the number of rate switchings in the network. Numerical results indicate that by sacrificing only 1% of transmission quality in terms of the average delay one can achieve more than 50% reduction in switching load of the network. Our analytical as well as numerical results confirm that the optimal policy is a threshold policy.

Jointly optimized bit-rate/delay control policy for wireless packet networks with fading channels

“…Since a stationary Markov process has the property of time-invariant transition probabilities, the transition probability is independent of the time index and can be written as (1) If we assume that the transitions only happen between adjacent states, we obtain (2) In a typical multipath propagation environment, the received signal envelope has the Rayleigh distribution. With additive Gaussian noise, the received instantaneous SNR is distributed exponentially with probability density function (PDF) (3) where is the average SNR. An FSMC model can be built to represent the time-varying behavior of the Rayleigh fading channel.…”

“…One of the major issues in wireless data networks is the bit-rate control problem [2], [3]. This is especially important in the downlink, since in a wireless data network most of the traffic flow is from the base station to mobiles, e.g., an Internet connection or a multimedia (voice/image/data) connection.…”

Hierarchical SIR and rate control on the forward link for CDMA data users under delay and error constraints

“…} be the vector that minimizes the required X i for user i (see equation (8)) , subject to the constraint that P RER i = ǫ 0 . Suppose the system is not underloaded, i.e., there exists some user j, such that R * j < R max .…”

“…After the 2-level algorithm converges, the mobile will use the resulting SIR targets as the targets for the power control algorithm in the next data segment. The mobile calculates the minimum required average SIR per bit X * i from equation (8) and sends it to the base station for rate determination. The base station chooses the values of…”

“…Though most of the work in the literature has primarily considered the reverse link, the results can be extended to the forward link. Forward link specific SIR and rate control can be found in [7,8] where some computation needs to be performed at the base station. A detailed description of the data rate adaption procedures used in practical systems such as in [1,9] can be found in [10].…”