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In the presence of heterogeneous service provider (SP) networks such as wireless local area networks and cellular networks, users have to make a choice. The quality of service provided and the price charged by an SP play a crucial role in this decision process. In this paper, we study the network selection behavior of mobile users. A novel probabilistic framework is presented, with explicit analytical expressions for the transition and steady state network selection probabilities of the users. The proposed framework utilizes the price charged and the utility obtained at the SPs in obtaining the transition probabilities, even in the presence of multi-homing users. Furthermore, network-level parameters such as call blocking probabilities and throughput are obtained in terms of the steady state probabilities. Numerical results indicate that the prices and utilities at the heterogeneous SPs have considerable impact on the overall network performance. [ABSTRACT FROM PUBLISHER]

We consider a space-time block coded system having L time slots and using decision feedback channel estimation with a finite window size. The channel matrix estimate is updated every L time slots by: 1) a least-squares (LS) estimate and 2) a minimum mean-square error (MMSE) estimate. Using a Markov model of the decision process, we analyze the decoding error probability (DEP) of this scheme in Rayleigh fading. The transition probability matrix is obtained by simulation of the decision process for a system using the Alamouti code. From this matrix, the DEP can be computed for any time shift. We find from computations that the DEP increases with increase in the time shift but tends to saturate with time to a steady-state value. It is also observed that both the state and the transition probabilities tend to saturate with the increase in average signal-to-noise ratio per diversity branch. [ABSTRACT FROM AUTHOR]

We analyze the error performance of minimum selection generalized selection combining (MS-GSC), in which the minimum number of diversity branches are selected such that their combined signal-to-noise ratio (SNR) is above a given threshold. A flat Rayleigh fading channel with independent and distinctly distributed branch SNRs is considered. By transforming the ordered instantaneous branch SNRS to their differences, we derive the distribution of the number of selected branches in closed form. We then modify the derivation of this distribution to get the characteristic function (cf.) of the combiner output SNR. This cf. is used to obtain the symbol error probability for different coherent digital modulation schemes. [ABSTRACT FROM AUTHOR]

We consider an antipodal signaling system using wavelet modulation (WM) with scale diversity over a frequency-selective fading channel. The channel introduces a random gain for each scale. These scale gains are estimated by sending a block of pilot symbols before the data. Coherent demodulation is carried out along with maximal-ratio combining using the estimated scale gains. From the characteristic function of the resulting decision variable, we analyze the bit error performance. For the case of large signal-to-noise ratio (SNR), we obtain a closed-form expression for the bit error probability (BEP). It is seen that BEP decreases with increase in the number of pilot symbols. We also find a significant improvement in BEP with increase in the number of scales for a fixed pilot length. It is also found that, when compared with frequency diversity, WM can perform better over a certain range of SNR, with the range decreasing with increase in the number of scales. [ABSTRACT FROM AUTHOR]

We propose cognitive spectrum sharing with generalized selection combining (GSC) at the secondary user (SU) in the presence of multiple primary transceivers with outdated channel information. Our main motivation is to determine the impact of GSC and outdated channel information on the outage probability of cognitive spectrum sharing subject to two practical power constraints: 1) maximum transmit power at the SU transmitter and 2) peak interference temperature at the primary user (PU) receiver. We derive new closed-form expressions for the exact and asymptotic outage probability in Rayleigh fading. Our expressions provide concise representations of the diversity order and the array gain. We confirm that the diversity order of GSC is entirely dependent on the secondary network and is equal to the available number of receiver antennas at the SU. This result is consistent with those of maximal-ratio combining (MRC) and selection combining (SC) in cognitive spectrum sharing. More importantly, our results show that the outage probability decreases with the increasing correlation coefficient of the outdated channel. [ABSTRACT FROM PUBLISHER]