Wahyul Amien Syafei

Implementation of K-Best method for MIMO decoder in WLAN 802.11n

WLAN IEEE 802.11n is recent wireless data communication technology which provides high throughput and high performance. These features are definitely determined by the strength of MIMO decoder. The existing MIMO decoder of WLAN 802.11n is based on linear method, i.e Zero Forcing (ZF) and Minimum Mean Square Error (MMSE). Both of them are low in complexity but poor in performance. In the other hand Maximum Likelihood Detection method demonstrates optimal performance but with very high in complexity. This paper presents our research in developing a high performance low complexity MIMO decoder for WlAN 802.11n by implementing K-Best method. Simulation of WLAN 802.11n 2×2 with QPSK, 16QAM, and 64QAM modulation order is conducted under channel model B of TGn. By target BER of 10-4, the performance and complexity of each decoder are analyzed. The results show that K-Best detector achieves near-MLD performance, only degrade 1 dB, and has much better performance compared to ZF and MMSE with average 12 dB to 8 dB. The complexity ratio of the K-Best to MLD will significantly decrease as the increasement of transmitter antena (Ntx) and modulation order, i.e 46,9 % for QPSK to 5,27 % for 64QAM in Ntx=2.

Performance investigation of high throughput WLAN 802.11n by receiver diversity and antenna spacing

The high throughput WLAN 802.11n exploits Multiple Input Multiple Output antenna to provide high throughput and high performance. It transmits the data into spatial streams to be more robust to multipath fading propagation environment. In this paper the performance of WLAN 802.11n is investigated by combining receiver diversity technique and antenna spacing on both transmitter and receiver. Configuration of 2×2 to 2×8 and 4×4 to 4×8 MIMO antennas with spacing varied every λ/4 between λ/4 to 2λ are investigated under in-door channel model. The more receiver antenna, the probability of signal fading is lessen, the better the performance is. The farther space between antennas, the lower the correlation and interference, the better the performance is with the cost of wider size of hardware.

Sphere based MIMO decoder for high throughput WLAN IEEE802.11n

WLAN 802.11n combines MIMO and OFDM to provide high throughput and performance wireless communications. High quality MIMO decoder is urgently required. The existing WLAN 802.11n devices implement linear method, i.e. Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) as MIMO decoder. Both methods are simple but low in performance. At the other side, non-linear but optimal method Maximum Likelihood (MLD) based MIMO decoder gives superior performance with the cost of very high complexity. This paper is addressed to present Sphere based MIMO decoder which is low in complexity but high in performance dedicated for WLAN 802.11n device. Simulation under in-door channel model shows significant improvement of performance. At BER 10−4, it gives 9 to 15,5 dB better than ZF and MMSE and only 2 to 3 dB worse than MLD based MIMO decoder. The computation complexity is also dramatically reduced especially when the number of involved antenna is increased.

Methods of MIMO decoders for very high throughput WLAN IEEE802.11ac

Exponential growing of wireless multimedia communications has forced the IEEE802.11 workgroup to define new standard of WLAN. It is named a Very High Throughput WLAN IEEE 802.11ac which exploits MIMO-OFDM technology to provide up to 6,9Gbps of throughput. MIMO decoder is the vital part of WLAN 802.11ac. It decodes the received signals to get back the transmitted information. There are many methods can be implemented in MIMO Decoder. The linear methods, such as Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) are simple but low in performance. At the other side, the well-known non-linear method called Maximum Likelihood Detection (MLD) measures the likelihood of the received signal to all symbol candidates. It gives an optimum performance by the cost of very high complexity. Between them, there are some sub-optimal methods, such as K-best, Trellis, and Sphere Detection. These three methods are low in complexity but give performance close to optimum. This paper is adressed to compare the performance and complexity of above methods as MIMO decoders for 8×8 WLAN 802.11ac. Observation is conducted under small room channel model.

Near optimum MIMO decoders for next generation very high throughput WLAN

This paper presents our research in developing high performance but low complexity MIMO decoders for the newest WLAN, i.e. 802.11ac. K-best and Trellis methods are proposed to develop the MIMO decoders. Their performances are observed and compared to MIMO decoders which are based on linear and optimal methods, i.e. ZF, MMSE, and ML. Run test of 2×2 MEMO, 64-QAM, Coding rate 3/4, and 40MHz of bandwidth with target BER 10-6 is conducted under in-door channel model. The proposed near optimum methods demonstrate superior performance compared to the linear ones and the complexity are significantly lower than MLD.

Design of self balancing pitch control in fixed wing unmanned aerial vehicle with fuzzy logic controller

In UAV flight controllers design, the occurrence of errors due to the delay in the system response to the reference signal from the pilot and the lack of stability in flat conditions due to interference or unbalanced mechanical load. When this happens UAV can not be controlled and the flight conditions can not be maintained any more. Fuzzy controller offers a solution for the development of UAVs stability controllers, specialized in the design of the autopilot system that controls the pitch angle of the UAV. This research has been developing a prototype of fixed wing UAV that can be controlled wirelessly and has ability to maintain the balance on the pitch angle of the flat conditions (self-balancing). Run test results show that the applied fuzzy method succesfully controls the pitch angle to maintain a flat condition the developed UAV.

Greetings from the general chair

Welcome to 2014 1st International Conference on Information Technology, Computer, And Electrical Engineering (ICITACEE) held in Semarang, the capital city of Central Java! This conference provides a forum for researchers, academicians, professionals, and students from various engineering backgrounds and also from cross- disciplinary research in the development and the design of Information Technology & Computer, Power System, Circuit & Control, and Communication Systems, as well as the Interdisciplinary topics to interact and to disseminate the latest issues and research.

Very high throughput WLAN system for ultra HD 4K video streaming

We have been developing a very high throughput WLAN system based on IEEE802.11acs criteria. It combines MIMO and OFDM technology to provide throughput over 1 Gbps for 150 feet propagation distance by using 80 MHz of bandiwdth on 5 GHz frequency band. 4 by 5 antennas MIMO is set to get 2nd-order diversity gain to maintain high throughput and performance. Greenfield preamble with novel phase rotation is employed to mitigate the overhead problem while reducing the peak to average power ratio of the signals. Run test to broadcast the ultra high definition video which resolution 4096 × 1714 pixels/frame with 30 frame/second under in-door channel model demonstrates an excellent performance of the developed system.