Ernest Kurniawan

Antenna selection technique for MIMO-OFDM systems over frequency selective Rayleigh fading channel

A joint transmit and receive antenna selection technique for MIMO-OFDM is presented. By appropriately ordering and tabulating the minimum channel sub-matrixs sub-stream signal to noise ratio in all subcarriers, an optimal antenna subset can be obtained. This procedure can be simplified further by analysing the inter-subcarrier correlation and by exploiting group selection methods. Complexity analyses on the proposed algorithm are presented, and performance improvements achievable are demonstrated through simulation studies.

Incremental Code Relaying Protocol for Cooperative Communications

In this paper, the application of rate-compatible punctured convolutional (RCPC) code into coded cooperation relay system is studied. As opposed to conventional coded cooperation systems, RCPC is attractive for its better spectral efficiency. In addition, the broadcast nature of relay transmission provides a new dimension to the system in the form of implicit feedback channel from relay to source. This allows the source node to justify the quality of information bits at relay node and react accordingly by taking over relays role to transmit the additional parity. At the destination, selection code combining is then performed, which provides a diversity benefit to the underlying RCPC code. The performance of the proposed scheme in terms of the number of correctly decoded bits (goodput), bit error probability, and the required number of slots for message transmission are then analysed. Extension to the case where there are multiple relays to assist the transmission is also discussed.

Sub Optimal Antenna Selection Method for MIMO-OFDM Systems

This paper presents sub optimal method to perform antenna selection in MIMO-OFDM systems. This method allows reduction in the complexity by exploiting inter-subcarrier correlation or through disjoint selection of transmit and receive antennas. Their performances and complexities are then analysed and contrasted with respect to conventional brute force method.

Relaying and Power Control Strategy for 2-Hop Distributed Cooperative Communication

This paper analyses the effect of relay node and the importance of power allocation scheme in cooperative relay networks. It is shown that adding relay node alone is not sufficient to improve system performance. Under a simplest scenario where relay node adopts decode and forward relaying, direct transmission may perform better under certain cases with equal total power constraints. Furthermore, in practical scenario when source node has to transmit its message to relay node before cooperatively transmitting it to destination, the existence of relay node may even degrade system performance. By adopting the right relaying technique and proper power allocation scheme, it is shown that cooperative relay transmission can be made strictly better than direct transmission.

Exploiting Antenna Selection Gain in IEEE 802.16 Broadband Wireless Access Systems

In this paper, enhanced space time coded diversity feature of IEEE 802.16e (amendment of 802.16-2004 standard for combined fixed and mobile broadband wireless access operation in licensed band), under 2048 points orthogonal frequency division multiple access (OFDMA) mode of operation, are evaluated. It is shown that the current transmit diversity matrix does not fully exploit selection gain available, and a modified transmit diversity scheme is then proposed. The performances of the new scheme are evaluated under different channel conditions according to Stanford University Interim (SUI) channel model, and the antenna selection gains achieved are summarised

Performance Analysis of MIMO Enabled Broadband Wireless Access System for Mobile Multimedia Applications

This paper presents performance comparisons between different multi antenna configurations of broadband wireless access systems based on IEEE 802.16e (amendment of 802.16-2004 standard for combined fixed and mobile broadband wireless access operation in licensed band), specifically on the 2048 points orthogonal frequency division multiple access (OFDMA) physical specification. The system is extensively simulated for different channel conditions and for different user parameters. Results of the experimental studies are then summarized

Error concealment scheme for MPEG-AAC

MPEG-AAC is the state-of-the-art in audio compression technology. Promising CD quality at 64 kbps, AAC is the leading option for low bandwidth audio streaming applications. In spite of the support from channel coding and the error resilience features of AAC itself, handling erroneous transmission requires the decoder to be equipped with error concealment scheme to cater for missing packets. However, complexity is limited by the real time requirement in this application. We present in this paper a novel scheme of error concealment, specifically for AAC. This scheme exploits the time domain aliasing cancellation property of MDCT based codec and the block-switching feature of AAC. Preliminary simulations show significant improvement in both error performance and subjective quality testing compared to general method of concealment. The scheme does not introduce major computational load, and hence suitable for real time low power decoder

Performance Analysis of Distributed Space Time Coding: A Geometric Approach

This paper evaluates the performance of distributed space time coding in generic ad-hoc network scenario. The condition where multiple nodes (confined within a certain geographical area) wanting to exchange information to one another is considered. Effect of different system parameters such as total number of nodes, path loss exponent, node density, and error threshold, toward overall system performance are analysed.

Successive Dirty Paper Coding: New Relaying Scheme for Cooperative Networks

The present paper proposes a new relaying scheme called successive dirty paper coding. Theoretical achievable rate of the scheme is derived and its performance is compared to other existing relaying schemes in terms of their outage probability. It is shown via numerical studies and supported by simulation analysis that the proposed scheme is able to achieve higher bandwidth efficiency by reusing relay slots to transmit new messages. An improvement of up to M-fold, where M is the average number of relay stages in every transmission, compared to traditional non-cooperative relaying is observed.

Heuristic Antenna Selection Algorithm for Multiuser Multi-Antenna Downlink

In this paper, antenna selection algorithm for mul- tiuser downlink systems where each terminal is equipped with multiple antennas is proposed. As opposed to point to point systems, the broadcast nature of the transmission complicates the selection process as the selection criteria must take into consideration performances of all users collectively. Moreover, computational complexity required needs to be kept as low as possible for practical reason. Exploiting duality between broadcast and multiple access channel, the proposed scheme provides a heuristic approach to selection process in order to maximise the sum-rate capacity of the system, and it is shown that a close to optimal performance can be attained at a considerably lower complexity.