Kyung Seung Ahn

Performance analysis of maximum ratio combining with imperfect channel estimation in the presence of cochannel interferences

In this paper, we analyze the performance of maximum ratio combining (MRC) systems with imperfect channel estimation in the presence of cochannel interference (CCI) with an arbitrary power interference-to-noise ratio (INR). The maximum combining weights are the imperfect estimates of the desired users fading channel coefficients and are assumed to be complex Gaussian distributed. The quantified measure for estimation error is the correlation coefficient between the true fading channel coefficients and their estimates. Exact closedform expressions are derived for the probability density function(pdf) of the signal-to-interference-plus-noise ratio (SINR), as well as performance metrics including outage probability and the average symbol error probability (ASEP) for some modulation formats. Simulation results demonstrate the accuracy of our theoretic analysis.

Shannon Capacity and Symbol Error Rate of Space-Time Block Codes in MIMO Rayleigh Channels With Channel estimation Error

Space-time block coding (STBC) is an attractive solution for improving quality in wireless links. In this paper, we analyze the impact of channel estimation error on the ergodic capacity and symbol error rate (SER) for space-time block coded multiple-input multiple-output (MIMO) systems. We derive a closed-form capacity expression over MIMO Rayleigh channels with channel estimation error. Moreover, we derive an exact closed-form SER for general PAM/PSK/QAM with channel estimation error. We show that, as expected, channel estimation error introduces the capacity loss and diversity gain loss. Furthermore, as the number of transmit and receive antennas increases, the sensitivity of the STBC system to channel estimation error increases. Simulation results demonstrate the accuracy of our analysis.

Performance analysis of MIMO-MRC system in the presence of multiple interferers and noise over rayleigh fading channels

In this paper, we analyze the performance of multiple-input multiple-output (MIMO) wireless communication links with transmit beamforming and maximum ratio combining (MRC), known as MIMO-MRC, in the presence of multiple interferers and noise over Rayleigh fading channels. First, exact closed-form expressions for the signal-to-noise-plus-interference-ratio (SINR) distribution are calculated, along with the outage probability of the SINR, and the moment generating function (MGF) of the SINR. Second, upper bound and approximation of the average symbol error rate (SER) for pulse amplitude modulation (PAM), quadrature amplitude modulation (QAM), and phase shift keying (PSK) with M-ary signaling are evaluated by using the MGF of the SINR. Third, an exact closed-form expression of the average SER for some modulation formats is derived. Finally, the analytical results are confirmed by numerical simulations.

Performance Analysis of MIMO-MRC Systems With Channel Estimation Error in the Presence of Cochannel Interferences

In this letter, we analyze the performance of multiple-input multiple-output (MIMO) wireless communications with transmit beamforming and maximum ratio combining (MRC), known as MIMO-MRC, with channel estimation error in the presence of cochannel interferences (CCIs). The quantified measure for channel estimation error is the correlation coefficient between the true fading channel coefficients and their estimates. Exact closed-form expressions for the statistical distribution of the signal-to-noise-plus-interference ratio (SINR), the outage probability of the SINR, and the average symbol error rate (ASER) for some modulation formats are derived. The analytical results are confirmed by numerical simulations.

Secrecy Performance of Maximum Ratio Diversity With Channel Estimation Error

In this letter, we analyze the performance of maximum-ratio combining (MRC) system with channel estimation error for physical layer security. The quantified measure for channel estimation error is the correlation coefficient between the true fading channel coefficients and their estimates. Exact closed-form expressions for secrecy performance including the statistical distribution of the signal-to-noise ratio (SNR), the secrecy outage probability and the secrecy capacity are derived. The analytical results are confirmed by numerical simulations.

Phase noise suppression algorithm for OFDM-based 60 GHz WLANs

In this paper, we investigate the OFDM-based wireless local area networks (WLANs) operating in the 60 GHz frequency band. The performance of OFDM system is severely degraded by the local oscillator phase noise, which causes both common phase error (CPE) and inter-carrier interference (ICI). We analyze the impact of phase noise on OFDM systems. Moreover, in order to reduce the phase noise problem, we consider the phase noise suppression (PNS) algorithm. Some numerical results are presented to illustrate the effectiveness of the PNS algorithm for OFDM-based 60 GHz WLANs.

Asymptotic Performance and Exact Symbol Error Probability Analysis of Orthogonal STBC in Spatially Correlated Rayleigh MIMO Channel

Space-time block coding is an attractive solution for improving quality in wireless links. In general, the multiple-input multiple-output (MIMO) channel is correlated by an amount that depends on the propagation environment as well as the polarization of the antenna elements and the spacing between them. In this paper, asymptotic performance and exact symbol error probability (SEP) of orthogonal space-time block code (STBC) are considered in spatially correlated Rayleigh fading MIMO channel. We derive the moment generating function (MGF) of effective signal-to-noise ration (SNR) after combining scheme at the receiver. Using the MGF of effective SNR, we calculate the probability density function (pdf) of the effective SNR and derive exact closed-form SEP expressions of PAM/PSK/QAM with M-ary signaling. We prove that the diversity order is given by the product of the rank of the transmit and receive correlation matrix. Moreover, we quantify the loss in coding gain due to the spatial correlation. Simulation results demonstrate that our analysis provides accuracy.

Symbol Error Probability for Space-Time Block Codes Over Spatially Correlated Rayleigh Fading Channels

In general, multi-input multi-output (MIMO) channel is correlated by an amount that depends on the propagation environment as well as the polarization of the antenna elements and the spacing between them. In this paper, an exact error probability of orthogonal space-time block codes is considered in spatially correlated Rayleigh fading channels. We derive a general formula for the symbol error probability (SEP) of orthogonal space-time block codes for general PSK/PAM/QAM over spatially correlated Rayleigh fading channels.

Outage Performance and Average Symbol Error Rate of M-QAM for Maximum Ratio Combining with Multiple Interferers

In this paper, we investigate the performance of maximum ratio combining (MRC) in the presence of multiple cochannel interferences over a flat Rayleigh fading channel. Closed-form expressions of signal-to-interference-plus-noise ratio (SINR), outage probability, and average symbol error rate (SER) of quadrature amplitude modulation (QAM) with M-ary signaling are obtained for unequal-power interference-to-noise ratio (INR). We also provide an upper-bound for the average SER using moment generating function (MGF) of the SINR. Moreover, we quantify the array gain loss between pure MRC (MRC system in the absence of CCI) and MRC system in the presence of CCI. Finally, we verify our analytical results by numerical simulations.

Asymptotic Performance Analysis of Orthogonal Space-Time Block Codes in Spatially Correlated Rician Fading Channel

In this letter, we analyze symbol error probability (SEP) and diversity gain of orthogonal space-time block codes (OSTBCs) in spatially correlated Rician fading channel. We derive the moment generating function (MGF) of an effective signal-to-noise ratio (SNR) at the receiver and use it to derive the SEP for M-PSK modulation. We use this result to show that the diversity gain is achieved by the product of the rank of the transmit and receive correlation matrix, and the loss in array gain is quantified as a function of the spatial correlation and the line of sight (LOS) component.