Dong Seog Han

Channel estimation based on path separation for DVB-T in long delay situations

A least square (LS) channel estimation with pilots uses interpolation to obtain the channel information for the positions of data subcarriers in orthogonal frequency division multiplexing (OFDM) systems. However, the interpolation introduces estimation errors in long delay channels that usually happen in single frequency networks (SFNs). In this paper, we propose an algorithm that estimates the accurate channel information by separating channel paths. The performance is compared with conventional algorithms for DVB-T in SFN conditions1.

Improvement of connectivity between infrastructure and consumer devices for infotainment services

The robust reception of network parameters is a very important issue for the successful deployment of mobile infotainment services, particularly in fast-moving environments. An infrastructure broadcasts service access-related messages to consumer devices. These access messages critically affect the connectivity between the consumer devices and service providers. This paper proposes an algorithm to increase the connectivity by collaborating consumer devices to share access information messages. The consumer device that receives the access message retransmits the message by attached it to its beacon message. This is performed only when there are neighboring consumer devices that did not receive the message. This paper also proposes an extended beacon message for this purpose. The proposed algorithm was evaluated with computer simulations.

Bidirectional equalizer arbitrated by Viterbi decoder path metrics

A bidirectional decision feedback equalizer (DFE) is proposed with the arbitration of the Viterbi decoder. The proposed DFE uses the minimum path metric between Viterbi decoders for the forward and reverse DFEs in the arbitration process. It has over 2 dB SNR gain against the conventional bidirectional DFE and the single DFE.

Performance of vehicular-to-infrastructure communication systems based on IEEE 802.11a

In this paper, the performance of vehicle to infrastructure (V2I) communications is evaluated based on the IEEE 802.11a protocol at 5.8GHz for ubiquitous transportation sensor networks. The end-to-end

Performance Analysis for Priority-Based Broadcast in Vehicular Networks

Transportation safety is one of the most important applications of vehicular ad hoc networks which is based on IEEE 802.11p. When a vehicle is in an emergency situation, a safety-related message is transmitted to the neighboring vehicles and infrastructures. Vehicles and infrastructures exchange periodic messages on vehicle position, traffic information, and so forth to provide various services. When the traffic load is very high, the emergency message cannot be delivered immediately. To overcome this situation, a priority-based transmission scheme is considered to guarantee the transmission of the emergency message. In this paper, the performance of vehicular communication networks is analyzed in two perspectives. Firstly, an analytical Markov chain model for vehicle-to-vehicle (V2V) ad hoc communication networks is proposed for broadcasting messages with priority based on the IEEE 802.11p wireless access for vehicular environments (WAVE) standard. Secondly, an analytic queuing model for vehicular communication networks is proposed to evaluate the network performance to deal with safety and nonsafety messages.

Channel estimation with pilot signal design for terrestrial UDTV using MISO technology

A time-domain channel estimation algorithm is proposed for ultrahigh-definition television (UDTV) with multi-input single-output (MISO) systems. The proposed algorithm can estimate a long channel exactly by arranging the impulsive signals in the time-domain through the pilot design in the frequency-domain.

Improved WiMedia system supporting MIMO for wireless HD STB and mobile device

We propose a multi-band (MB) — orthogonal frequency division multiplexing (OFDM) ultra wideband (UWB) system for the wireless transmission of high-definition (HD) video signals from a set-top box to HD monitors. The system supports both single and multiple antennas by improving WiMedia. The proposed system with multiple antennas having a diversity order of four can support a data rate of at least 1 Gbps with reduced complexity. The proposed WiMedia system with multiple-input multiple-output (MIMO) technology is very robust against to the shadow fading.

Navigating through dynamic indoor environments using WIFI for smartphones

In recent days with a huge mass deployment of wireless networks, smartphones and various related services, different navigation techniques have been developed for indoor environments. Leveraging on these wireless networks, this paper proposes an indoor navigation model for a smartphone using WIFI. While a number of methods have been developed using received signal strength (RSS) based fingerprinting; only seldom approaches consider the dynamicity of the indoor environments. To tackle this limitation, we propose a positioning algorithm based on RSSI - fingerprinting and Manhattan distance which addresses navigation in a rapidly changing indoor environment. The model described is one of the efficient methods in terms of memory and battery consumption.

A Fast Suboptimal Algorithm for Detection of 16-QAM Signaling in MIMO Channels

We develop a computationally efficient approximation of the maximum likelihood (ML) detector for 16 quadrature amplitude modulation (16-QAM) in multiple-input multiple-output (MIMO) systems. The detector is based on solving a convex relaxation of the ML problem by an affine-scaling cyclic Barzila-Borwein method for box constrained optimization. Simulation results in a random MIMO system show that this proposed approach outperforms the conventional decorrelator detector and is similar to the semidefinite relaxation (SDR) detector. However, we should note that the complexity of the proposed approach is less than that of those detectors. In the case of 8 antennas and 4 users, about 99% fewer computations are required than the SDR and ML detectors.

Indoor navigation using WiFi for smartphones: An improved Kalman filter based approach

This paper proposes an indoor navigation technique for a smartphone using WiFi. An improved Kalman filter (IKF) is proposed to navigate in dynamic indoor environments with the fingerprinting technique. The results indicate that the IKF shows improved accuracy when compared to the conventional Kalman filter in a real-time scenario.