Yoo-Seung Song

A practical approach for channel problem detection and adaptation in tactical radio systems

Soldier-based tactical radio systems in the battlefield have tendencies to be severely affected by various phenomenon such as signal jamming and environment deterioration. This is because many types of wireless handheld and manpack devices carried by soldiers may not have efficient algorithms or the hardware for adapting the device to these conditions. Taking on the advantage that most of these devices use software-defined radios but do not fully utilize its functionalities, we present channel quality estimation and channel adaptation algorithms that can solve the problems of these devices. We utilize simple and practical channel problem detection methods by constantly monitoring the channel quality parameters such as signal-to-interference-noise ratio and clear channel assessment value while inducing low overhead. Furthermore, we propose efficient channel adaptation methods that can quickly sense and avoid deteriorated channel conditions. Via the experimental studies, we implement our proposed scheme on actual testbeds and show that it can improve the performance and mission-criticality of the tactical networks.

Digital automatic gain control and DC offset cancellation for IEEE 802.11n Wireless LANs

In this paper, the proposed AGC circuit is designed to adjust the strength of the received signal to a near constant optimum power level within the dynamic range of various signal processing components in the received signal path. Moreover, it can be used to dynamically control the gain of the received signal with residual DC offset and large variations caused by multi-path fading with time and frequency offset in order to ensure timely gain control for the received signal and provide reliable transmission with stable gain.

Adaptive wireless mesh networks architecture based on IEEE 802.11s for public surveillance

We propose and demonstrate an adaptive wireless mesh network architecture for public surveillance and monitoring. The proposed architecture is based on IEEE 802.11s WLAN mesh network, which is enhanced to provide adaptation depending on the environment of the network. We first introduce the implementation architecture of the adaptive mesh, and then describe the demonstration of the network on the wireless mesh camera sensor testbed.

Multi-Gigabit MAC Structure Design for IMT-Advanced Wireless Nomadic Access

In this paper, a new IMT-Advanced wireless communication system employing the proposed MAC frame structures was implemented and demonstrated. The proposed MAC frame structures are designed to provide Gbps data service under the nomadic environment. The implemented system provided near 1.8Gbps MAC throughput. It is shown that the implemented system with the proposed MAC frame structures can meet IMT-Advanced wireless access requirements and it is one of the promising solutions for the future multi-gigabit wireless communication systems.

MAC implementation for IMT-advanced multi-gigabit nomadic systems

In this paper, high performance MAC is designed and implemented to support multi-gigabit nomadic access systems. New algorithms and Control channels are introduced for low MAC latency and high MAC throughput. The new multi-gigabit nomadic/local area wireless access, called NoLA, is implemented using the proposed MAC. NoLA demonstrated the multi-gigabit service with full HD video streams where the proposed high performance MAC supports the 84 full HD video streams in real time. The implemented NoLA system shows near 1.8 Gbps MAC throughput, which can meet the requirements of the gigabit IMT-advanced wireless nomadic access. It is proved that the proposed high performance MAC used in NoLA can be one of the promising solutions for the future multi-gigabit wireless communication systems.

Multi-Gbps MAC Design and Real-Time Experiment for IMT-Advanced Wireless Nomadic Access

In this paper, high performance MAC is designed and implemented to support multi-gigabit physical layer. New algorithms and Control channels are introduced for low MAC latency and high MAC throughput. The new multi-gigabit nomadic/local area wireless access, called NoLA, is implemented using the proposed MAC. NoLA demonstrated the multi-gigabit service with full HD video streams where the proposed high performance MAC supports the 84 full HD video streams in real time. The implemented NoLA system shows near 1.8Gbps MAC throughput, which can meet the requirements of the gigabit IMT-Advanced wireless nomadic access. It is proved that the proposed high performance MAC used in NoLA can be one of the promising solutions for the future multi-gigabit wireless communication systems.