Young-Hyun Jeon

Performance Analysis of Location-Based Loading Control for Downlink FH-OFDMA Systems

A strategy for avoiding the ICI (Inter Cell Interference) termed LBLC (Location-Based Loading Control) for downlink FH-OFDMA (Frequency Hopping Orthogonal Frequency Division Multiple Access) systems over multi-cell environments with a frequency reuse factor of 1 is described. To mitigate the effect of the ICI, a closed form of outage probability is derived and is utilized as a criterion for obtaining an optimal set of loading parameters. For a given target QoS (Quality of Service), region partitioning is performed and a carrier loading ratio at each region is obtained. An optimal set of loading parameters according to each region can be obtained from the simulations. In addition, the feasibility of the LBLC technique is demonstrated.

WLC32-6: A Cell Search Technique based on Known Postfix for OFDM Cellular Systems

A cell search technique utilizing a known postfix for OFDM (orthogonal frequency division multiplexing) cellular systems is described. The known postfix is generated in the time domain by inserting pilots in the frequency domain and plays the role of the cyclic prefix in general OFDM systems. Since it demonstrates good correlation properties, it can be facilitated to synchronize each symbol with an identified postfix. In this paper, two different known postfixes are allocated to each cell. One is used for cell identification and symbol synchronization, which is designed to be different among neighboring cells. The other is used for frame synchronization and is the same for all cells. In the simulation, the cell search is accomplished with a probability greater than 10-3 at -27 dB in a vehicular channel. Even at -30 dB, the cell search probability is greater than 10-2 in a pedestrian channel as well as 10-3 in the AWGN (additive white Gaussian noise) channel.

Weighted MMSE Precoder Designs for Sum-Utility Maximization in Multi-User SWIPT Network-MIMO With Per-BS Power Constraints

Simultaneous wireless information and power transfer (SWIPT) is a promising technique to transfer information and energy signals at the same time and frequency utilizing the multi-input multi-output (MIMO) beamforming. In this correspondence, the SWIPT MIMO technique is realized in the multicell cooperative transmission environment, namely, network-MIMO where the signals from different base-stations (BSs) to all the mobile users can be jointly designed based on the perfect knowledge of the downlink channels and transmit messages. To develop an efficient precoding matrix, we adopt the weighted minimum mean squared error criterion that can be generally applied to the sum-utility maximization of each receivers information rate. In the SWIPT network-MIMO, a number of constraints arise including the power constraint at each BS, namely, the per-BS power constraints and the energy constraint at the energy harvesting users, which makes the problem challenging. A main contribution of the paper is to propose a simple bisection-based algorithm that finds a solution. The efficiency of the proposed algorithm is verified via computer simulation results.

Performance gain analysis of dynamic carrier allocation using order statistics

It is well known that the diversity gain attained by DCA (Dynamic Channel Allocation) is generally very high over OFDM (Orthogonal Frequency Division Multiplexing)-based broadband networks. This paper introduces a numerical approach for measuring the performance gain afforded by DCA. In the mathematical analysis, the property of order statistics is adopted to derive the upper bound of the expected throughput via the use of DCA. In the simulation, it was possible to achieve a gain of 5 dB by exploiting multi-user and spectral diversities when the number of users is 16 and the total number of subcarriers is 256.

Known Postfix Based Cell Search Technique for OFDM Cellular Systems

A cell search technique utilizing a known postfix for OFDM (orthogonal frequency division multiplexing) cellular systems is described. The known postfix is generated in the time domain by inserting pilots in the frequency domain and plays the role of the cyclic prefix in general OFDM systems. Since it demonstrates good correlation properties, it can be facilitated to synchronize each symbol with an identified postfix. In this paper, two different known postfixes are allocated to each cell. One is used for cell identification and symbol synchronization, which is designed to be different among neighboring cells. The other is used for frame synchronization and is the same for all cells. In the simulation, the cell search is accomplished with a probability greater than 10 -3 at -27 dB in a vehicular channel. Even at -30 dB, the cell search probability is greater than 10 -2 in a pedestrian channel as well as 10 -3 in the AWGN (additive white gaussian noise) channel.