Myoung-Won Lee

Comparison of handover schemes for 3GPP Long Term Evolution and 3GPP2 Ultra Mobile Broadband

As a radio access technology for next generation cellular networks, 3GPP and 3GPP2 are standardizing long term evolution (LTE) and ultra mobile broadband (UMB), respectively. In this paper, we compare the handover schemes of both technologies in three aspects, i.e., interruption time of a user plane, required wireless resources and the overhead for avoiding packet reordering. The comparison results show that UMB achieves shorter interruption time and less overhead for reordering avoidance while LTE incurs less resource waste.

Codebook Based Space Division Multiple Access with Partial Side Information

In this letter, a codebook based multiuser MIMO precoding scheme is proposed for a space-division multiple access (SDMA) system with limited feedback. Focusing on the case of SDMA systems with two transmit antennas, a precoder codebook design is proposed based on the idea that a precoder inducing larger fluctuations in the signal to interference and noise ratio (SINK) at each link can lead to a larger gain in terms of multiuser diversity. It is shown that the proposed multiuser MIMO precoding outperforms existing multiuser MIMO techniques in terms of the average system throughput.

Capacity Analysis of Multiuser Diversity Combined with Dual MIMO Systems

In this letter, the system capacity of multiuser diversity combined with spatial multiplexing schemes is analyzed. An analytic expression is derived for the ergodic system capacity with multiuser scheduling and dual multi-input multi-output (MIMO) systems by using a tight lower bound of the link capacity. The proposed analytic approach is verified through comparisons between analytic and simulated results, and is shown to make fairly precise predictions of the ergodic system capacity and the scheduling gains even when the numbers of antennas and users are small.

Capacity Analysis of Wireless Packet Data Systems with Transmit Diversity in a Correlated Rayleigh Fading Environment

A precise analysis of the capacity of a wireless downlink packet data system with a fair scheduler is presented. We assume the use of a transmit diversity scheme is operating at each link under the assumption of spatially correlated Rayleigh fading. Numerical results show that spatial fading correlation of the channel improves the capacity of multiuser diversity by reducing the space diversity gain of transmit diversity in each link.

System level performance evaluation of spatial multiplexing with per common basis rate control

In this paper, we evaluate the system level perfor- mance of a spatial multiplexing with per common basis rate control (PCBRC) in which the active bases are selected at the receiver from the common unitary basis set known at both receiving and transmitting ends, conveyed to the transmitter using limited feedback, and assembled into a precoding matrix at the transmitter. System level capacity evaluation using spatial channel model (SCM) shows that the proposed PCBRC out- performs multi-mode antenna selection and precoder codebook design methods even with the same or lower feedback rate.