Uk Jang

CoMP-CSB for ICI Nulling with User Selection

The capacity of downlink multiple-input multiple-output (MIMO) cellular networks is significantly limited by inter-cell interference (ICI), particularly at cell boundaries. Recently, two types of coordinated multiple point transmission (CoMP) technologies, joint processing and transmission (JPT) and coordinated scheduling and beamforming (CSB), were proposed. These technologies are intended for the latest cellular communication standard in order to improve the performance of cell-edge users who suffer from significant ICI. In this paper, we propose an ICI cancellation technique based on a user selection algorithm for CoMP-CSB. Under partial channel state information (CSI) and no data sharing condition, each base station (BS) concentrates more on the direction of interference to the adjacent cells users, during the user selection process. Unlike prior concepts for a single-cell environment, in which each BS generates a precoding matrix for selected users to be served, the proposed technique considers the effects of interference to users located in adjacent cells. Although there are obvious trade-offs between ICI mitigation and the number of simultaneous scheduled users in terms of system capacity, the simulation results demonstrate that our proposed algorithm achieves higher sector throughput and is more robust against ICI if the system is limited by interference. Furthermore, through simulation we are able to obtain the preferred option for the coordination distance (R) and the number of degrees of freedom for ICI nulling (ξ).

Optimal Carrier Loading Control for the Enhancement of Visual Quality over OFDMA Cellular Networks

A recent dynamic increase in demand for wireless multimedia services has greatly accelerated the research on dynamic channel adaptation of high quality video applications. In this paper, we explore a theoretical approach to cross-layer optimization between multimedia and wireless networks by means of a quality criterion termed ldquovisual throughputrdquo for downlink video transmission using a layered coding algorithm. We obtain the optimal loading ratio of orthogonal frequency division multiple access (OFDMA) subcarriers through an optimization problem balancing the tradeoff relationship between inter-cell interference (ICI) and channel throughput. Through numerical link capacity analysis, we show that the upper bounds of the visual throughput gain at the cell boundary is obtained at about 27%.

Transmit Beamforming Based Inter-Cell Interference Alignment and User Selection with CoMP

Recently, two types of coordinated multiple point transmission (CoMP) technologies - joint processing and transmission (JPT) and coordinated scheduling and beamforming(CSB) - have been proposed to the latest cellular communication standard named as a Network MIMO, to improve the performance of cell-edge users who suffer strong ICI. In this paper, we investigate an ICI cancelation employing a user selection algorithm associated with CoMP-CSB, which is more practically used for cellular networks. Under the partial channel state information (CSI) and no data sharing condition, each base station (BS)concentrates more on the direction of the interference to users located at the adjacent cells during the user selection process.

Downlink Transmit Beamforming for Inter-Cell Interference Mitigation with BS Cooperation

The capacity of downlink multiple-input multiple-output (MIMO) cellular network is significantly limited by inter-cell interference (ICI), especially at the cell boundary. In this paper, we propose an ICI cancelation employing a user selection algorithm associated with CoMP-CSB, which is more practically used for cellular networks. Under the partial channel state information (CSI) and no data sharing condition, each base station (BS) concentrates more on the direction of the interference to users located at the adjacent cells during the user selection process. Although it is obvious that there are trade-offs between the ICI mitigation and the number of simultaneous scheduled users in terms of system capacity, the simulation results show that our proposed algorithm achieves higher sector throughput and is more robust against the ICI when the system is limited by interference.

Optimal power allocation for minimizing visual distortion over MIMO communication systems

A recent dynamic increase in demand for wireless multimedia services has greatly accelerated the research on cross layer optimization techniques for transmitting multimedia data over wireless channel. In this paper, we explore a novel theoretical approach for joint optimization between the rate distortion (RD) of H.264/AVC video and the link-capacity of MIMO parallel subchannels. We obtain the optimal power level of subchannels through an optimization problem to minimize total visual distortion. In the simulation results, compared to the water filling (WF) method, the proposed scheme provides better results in aspects of visual quality in the face of sum rate loss.

ROI-based Video Transmission using Cooperative Diversity over Wireless Ad-hoc Networks

Cooperative diversity is a cooperative technique which exploits user diversity by decoding the combined signal of the relayed signal and the direct signal in wireless multi-hop networks. Using the cooperation, the performance of the network system can be improved because cooperative diversity which is very strong against the fading channels can be achieved. In this paper, we propose the technique that provides the enhanced visual quality of the reconstructed video using the cooperative diversity with the FMO which is the error resilience tool of H.264/AVC standardization over wireless networks. The eye-tracker can detect the gaze point of user and transmit the gaze information to the nodes. After receiving the gaze information of user, each node performs ROI encoding according to the received gaze information. After encoding, video sources are divided into ROI and Non-ROI. Through the simulation results, the better visual quality of the reconstructed video is achieved when ROI and Non-ROI are transmitted through different channels.