Yuk Ching Chow

Threshold Controlling Scheme for Adaptive Modulation and Coding System

Adaptive modulation and coding scheme (AMC) is an effective way to achieve high data rate communication. In AMC system, the key issue is to determine the switching rule for different modulation and coding scheme (MCS). In this paper, adaptive threshold controlling scheme for AMC is proposed. The proposed scheme controls switching thresholds according to target block error rate. Simulation results have shown that the throughput performance of the proposed scheme is very close to the performance, which obtained by the optimum SIR thresholds.

Threshold controlling scheme for adaptive modulation and coding system

Adaptive modulation and coding scheme (AMC) is an effective way to achieve high data rate communication. In AMC system, the key issue is to determine the switching rule for different modulation and coding scheme (MCS). In this paper, adaptive threshold controlling scheme for AMC is proposed. The proposed scheme controls switching thresholds according to target block error rate. Simulation results have shown that the throughput performance of the proposed scheme is very close to the performance, which obtained by the optimum SIR thresholds.

Common channel interference cancellation for a spread spectrum system

This paper has mainly focussed on evaluating the potential performance improvements that accrue from cancelling the common pilot channels interference in terms of bit error rate performance for downlink applications. The impact of different cancellation strategies - sequential (SIC) and parallel (PIC) - has been presented for various data rates and channel profiles. With the investigative analysis appertaining to the FDD element of the UTRAN specified by 3GPP, the performance of the interference cancellation unit is primarily based on the elimination of the cross-correlation of the spreading codes over time dispersive wireless conditions. With a sound channel estimate, the results are shown to achieve near interference free performance, highlighting the potentiality of these interference cancellation schemes. Their versatility and robustness against channel estimation errors is further demonstrated by a relative performance comparison for a diversified range of data rates, pilot-to-data power ratios and channel conditions.

Performance enhancement analysis for a DS-CDMA system

This paper has addressed the impact of different interference cancellation algorithms - sequential interference cancellation (SIC) and parallel interference cancellation (PIC) - for various data rates and channel profiles that mainly focuses on the evaluation of the performance improvements that accrue from cancelling the common pilot channels interference in terms of bit error rate performance for downlink applications of a CDMA system. With these advanced signal processing strategies pertaining to the frequency division duplexing (FDD) element of the UMTS terrestrial radio access network (UTRAN) specified by 3GPP, apriori knowledge of the cross-correlation properties of the spreading codes for interfering common signalling channels is utilised in reducing interference under time dispersive wireless channel conditions. Performance analysis, with its dependency on the quality of the channel estimate, emphasises the potentiality of these interference cancellation schemes and their robustness against channel estimation errors.

Error-bound formulation for multichannel reception of M-DPSK and pilot-aided M-PSK over Rayleigh-fading channels with postdetection combining

Upper bounds for symbol-error probability are developed for multichannel reception of M-ary phase-shift keying (M-PSK) over frequency-flat Rayleigh-fading channels. Differential coherent demodulation of differentially encoded M-PSK (M-DPSK), pilot-tone aided coherent demodulation of M-PSK (PTA M-CPSK) and pilot-symbol aided coherent demodulation of M-PSK (PSA M-CPSK) are considered in the formulation. The bounds enable the investigation of the effects of fading correlation and unequal average power level between channels using postdetection diversity reception with maximal-ratio combining. Error-performance degradation due to imperfect demodulation effects, such as Doppler spread in M-DPSK schemes, noisy reference signals in PTA M-CPSK, and PSA M-CPSK schemes can be taken into account in the formulation. Exact bit-error probabilities for both binary and quaternary phase-shift keying are also derived.