| Title | A Realization of Determinant Criterion for STTC Design |
| Author | *Tatsuki Fukuda, Shingo Otsu, Yuta Tokunaga, Hua-An Zhao (Graduate School of Science and Technology, Kumamoto University, Japan) |
| Page | pp. 61 - 64 |
| Keyword | wireless communication, MIMO, Space-Time Trellis Codes, distance matrix |
| Abstract | In a MIMO (Multiple-Input Multiple-Output) system, space-time trellis coding (STTC) is one kind of space-time coding technique which can obtain both of high diversity and coding gain. In this paper, we propose a high-speed algorithm to solve the determinant calculations in determinant criterion of STTC. Some experimental results indicate that this algorithm is very available for developing an effective signaling scheme of space-time trellis codes. |
| Title | BER of Fast Frequency Hopping Spread Spectrum Over Flat Rayleigh Fading Channel in Hostile Jammers |
| Author | *Abid Yahya (CEDEC, Universiti Sains Malaysia, Malaysia), Othman Sidek (Director,CEDEC, Universiti Sains Malaysia, Malaysia), Farid Ghani (Universiti Malaysia Perlis, Malaysia) |
| Page | pp. 65 - 68 |
| Keyword | frequency hopping |
| Abstract | This paper demonstrates the execution and performance of frequency hopping spread spectrum system employing noncoherent frequency shift keyed (NCFSK) modulation. Fast frequency hopping is exploited as a diversity technique over flat Rayleigh fading channel with partial band noise jamming and additive white noise Gaussian (AWGN). The potentiality of the aforementioned system has then, ascertained by measuring the probability of error. The simulation results evince that the chance of getting 0 errors falls to about 1 percent. The overall fast frequency hopping (FFH) system has approximately 29 percent chance of producing 35 errors or less. |
| Title | Antenna-Permutation Channel-Vector Quantization for Finite Rate Feedback in Block-Diagonalizing Beamforming Multiuser MIMO-OFDM Systems |
| Author | *Masaaki Fujii (Samsung Yokohama Research Institute Co., Ltd., Japan) |
| Page | pp. 69 - 72 |
| Keyword | multiuser MIMO, OFDM, block-diagonalizing beamforming, finite rate feedback, MLD |
| Abstract | An antenna-permutation (AP) scheme is described for channel vector quantization (CVQ) in block-diagonalizing beamforming (BDBF) multiuser multiple-input and multiple output (MU-MIMO) orthogonal frequency-division multiplexing (OFDM) systems with four receive antennas. The channel vectors for two receive antennas are quantized to a single quantization vector for finite rate feedback by maximum-ratio transmission (MRT). The combinations of two antennas from among the four receive antennas are cyclically permutated for subcarriers. By doing so, BDBF provides severer frequency selectivity. This can be exploited by channel decoding as a larger frequency diversity gain. Simulation results demonstrate that AP-MRT-CVQ with 12-bit quantization achieved average packet error rate performance close to that in the case where perfect channel state information at the transmitter is available. |
| Title | Modified EDCF to Improve the Performance of IEEE 802.11 e Contention-Based Channel Access |
| Author | *Wen-Yen Lin (Vanung University, Taiwan), Jung-Shyr Wu (National Central University, Taiwan) |
| Page | pp. 73 - 76 |
| Keyword | WLAN, EDCF, QoS, 802.11e, Wireless |
| Abstract | In this paper we propose a modified EDCF scheme, M-EDCF, to improve the Quality of Service (QoS) of the IEEE 802.11e wireless network. The IEEE 802.11e standard is presented to support QoS at medium access control level using a priority scheme by differentiating the inter-frame space and the initial window size. In addition to providing relative priorities by adjusting the size of the Contention Window (CW) of each traffic class, our proposed scheme, M-EDCF, also consider the effect of a back_off_timer to avoid unnecessary collisions. Our study shows that in either in heavy or light traffic load our proposed scheme can provide better quality for both high priority and low priority packets than either the AEDCF |
| Title | Synchronized Behavior of FHSS Against External Interference |
| Author | Othman Sidek (Director,CEDEC, Universiti Sains Malaysia, Malaysia), *Abid Yahya (CEDEC, Universiti Sains Malaysia, Malaysia) |
| Page | pp. 77 - 80 |
| Keyword | Frequency hopping spread spectrum, Matched filter, Jammer, Broadband Noise, Narrowband jammer |
| Abstract | This paper demonstrates the execution and performance of frequency hopping spread spectrum (FHSS) in hostile jamming surroundings as correspond to conventional system. The system in this paper is confined to the merest assessments establish on the power ratio between the signal and entire interference. In scheming an antijam FHSS system, the spread bandwidth, , is by and large fixed at the start, and repeatedly with the usable bandwidth. Two rectangular bandpass signals have been diagrammed and the observance matrices are incurred by adding signal to jammer, arranging the jammer amplitude at 6 with matched filter output. From the simulation results it has revealed that plain signal is entirely masked by the jammer and is not noticeably ascertained at the filter output, the FHSS is the one, time constricted by the matched filter, is evident uniquely. |