Seok Ho Cheon

QoS-Oriented Intersystem Handover Between IEEE 802.11b and Overlay Networks

In this paper, we consider the quality-of-service (QoS)-oriented intersystem handover between the IEEE 802.11b network and the overlay network. We propose the handover scheme and algorithm that guarantee to simultaneously meet the three key QoS parameters, that is, the minimum data rate, the maximum data block delay, and the maximum bit error rate, for the arbitrary number of downlink and uplink multiservice connections. In addition to the QoS requirements, our intersystem handover scheme guarantees to keep the call-dropping probability during the handover and the sum of the average number of ping-pong events during the entry to and the exit from the IEEE 802.11b system below the predetermined values. We define the IEEE 802.11b network as the priority network for the mobile station. Thus, we maximize the time during which the mobile station is served by the IEEE 802.11b network while satisfying the QoS requirements in both networks, as well as the maximum call-dropping probability and the maximum average number of ping-pong event constraints. To solve this task, we propose a novel intersystem handover scheme that utilizes the minimum signal-to-noise ratio threshold, entry hysteresis, and exit hysteresis.

Joint Fragment Size and Transmission Rate Optimization for Request-to-Send/Clear-to-send Mechanism of IEEE 802.11b Distributed Coordination Function

In this paper we theoretically perform joint fragment size and transmission rate optimization for request-to-send/clear-to-send mechanism of IEEE 802.11b distributed coordination function considering both collisions due to system load and frame errors due to nonideal channel conditions. We have chosen system throughput maximization as the optimization criteria

WLC17-4: Load-Balancing QoS-Guaranteed Handover in the IEEE 802.16e OFDMA Network

In this paper we propose a load-balancing QoS- guaranteed handover algorithm in the IEEE 802.16e OFDMA network. We describe our system load model for the IEEE 802.16e OFDMA network and propose the optimal and fast handover algorithms. We evaluate our fast handover algorithm using system level simulation of the IEEE 802.16e OFDMA network. Our fast load-balancing handover algorithm eliminates overloading, thus guarantees meeting the QoS requirements of the users. It also provides a considerable throughput gain over the traditional SINR-based handover algorithm.

QoS-Guaranteed Cross-Layer Adaptive Transmission Algorithms with Selective ARQ for the IEEE 802.16 OFDMA System

We consider the IEEE 802.16 OFDMA system with the frequency diversity frame structure. We perform adaptive coding and modulation, allocation of the time-frequency resource and transmit power to the downlink and uplink service flows, scheduled for transmission in the current frame. We also adapt the position of the frame boundary between the uplink and downlink subframes. We propose three heuristic algorithms that minimize the total power transmitted in both downlink and uplink subframes subject to the maximum transmission power constraints and the available time-frequency resource constraint, while satisfying the QoS requirements for all downlink and uplink service flows scheduled for transmission. Our algorithms take into account the MAC and PHY layers processing in case of ARQ. We evaluate the proposed heuristic algorithms by the system level simulation of the IEEE 802.16 network.

Load-Balancing QOS-Guaranteed Handover in the IEEE 802.11 Network

In this paper we propose the load-balancing QoS-guaranteed handover algorithm in the IEEE 802.11 network. We present our system load model in the IEEE 802.11 network and describe the optimal and fast handover algorithms. We evaluate our fast handover algorithm using system level simulation of the IEEE 802.11b network. Our fast load-balancing handover algorithm eliminates the overloading, thus guarantees meeting the QoS requirements of the users. It also provides a considerable throughput gain over the SNR-based handover algorithm

Joint fragment size and transmission rate optimization for basic access mechanism of IEEE 802.11b distributed coordination function

In this paper we theoretically perform joint fragment size and transmission rate optimization for basic access mechanism of IEEE 802.11b distributed coordination function considering both collisions due to system load and frame errors due to non-ideal channel conditions. We have chosen system throughput maximization as the optimization criteria

Optimal Average Number of Data Block Transmissions for the ARQ Mechanism in the IEEE 802.16 OFDMA System

In this paper for the IEEE 802.16 OFDMA system we propose the fast algorithm to find the optimal average number of data block transmissions that minimizes the total downlink and uplink transmission power subject to satisfying QoS requirements. We show that the optimal average number of data block transmissions in the IEEE 802.16 OFDMA system is almost independent of the coding and modulation scheme used, propagation channel model, and data block size. In the IEEE 802.16 OFDMA system the optimal average number of data block transmissions is very close to 1.18

Joint fragment size, transmission rate, and request-to-send/clear-to-send threshold optimization for IEEE 802.11b distributed coordination function

In this paper we theoretically perform joint fragment size, transmission rate, and request-to-send/clear-to-send threshold optimization for IEEE 802.11b distributed coordination function considering both collisions due to system load and frame errors due to non-ideal channel conditions. We have chosen system throughput maximization as the optimization criteria.