Soon Young Yoon

Iterative Joint Detection and Decoding for MIMO-OFDM Wireless Communications

In this paper, we propose a simplified iterative joint detection and decoding (IJDD) scheme for MIMO-OFDM communications, which reduces the extremely high computational complexity of conventional iterative joint detection and decoding receiver with negligible performance degradation. For the MIMO detection, we propose a simplified maximum likelihood detection (MLD), which reduce the complexity of conventional MLD. The performance and computational complexity of the proposed scheme are compared with those of minimum mean squared error-ordered successive interference cancellation (MMSE-OSIC) receiver and maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD), which is known as to show near ML performance. Simulation results show that the proposed scheme outperforms the QRM-MLD with the half of computational complexity at a 1 Gbps data rate with 4 times 4 MIMO configuration, 16 QAM, the low-density parity-check (LDPC) code of 5/6 code rate and 90 MHz bandwidth.

Mobile data service QoE analytics and optimization

Quality of Experience (QoE) has emerged as the key performance metric to evaluate end-user service quality perception. We propose a system for video and web QoE assessment in LTE networks that we call QoE Analytics system. We build the proposed system and run it on a LTE network and successfully estimates QoE metrics per UE in real-time by inspecting user plane data on S1 interface without any QoE report from UEs. QoE metrics measured by QoE Analytics are verified to be in close match to actual UE observations such as initial playout delay, rebuffering percentage and rebuffering duration for video applications and download time for web traffic. Optimization of eNB scheduler performance based on this real-time QoE Analytics feedback is demonstrated by video QoE-aware scheduler and a significant improvement in QoE metrics is observed in congested situation.

A weighted parallel interference cancellation detector for convolutionally coded CDMA systems

A weighted parallel interference cancellation (PIC) detector with symbol-by-symbol weight determination is proposed for convolutionally coded code division multiple access (CDMA) systems. The proposed weighted PIC detector performs jointly post decoding PIC and weighted PIC. A soft-output Viterbi algorithm (SOVA) is employed as the decoder for the post-decoding PIC and generates the information bit log-likelihood ratio (LLR). The bit LLR is translated into symbol LLR, and the weight for weighted PIC is determined based on the statistical characteristics of the symbol LLR. Simulation results show that the proposed weighted PIC detector outperforms the weighted PIC detectors taking empirical weights under the interference-limited environments.

Forward link performance of medium access control for IS-2000

IS-2000, which is one of the major third generation cellular mobile radio transmission technologies, supports two classes of operation modes for packet data service: P1 and P2. This paper presents the forward link performance of P2 operation compared to that of P1. The advantage of P2 over P1 can be stated in several points of view. First, P2 can provide better effective rate and more available bandwidth than P1. Second, P2 can support more simultaneous subscribers than P1. These advantages are shown through simulations with WWW traffic modeling.