Efficient soft bit estimation for joint iterative multiple-input multiple-output detection

Ahmed, Saleem,Sooyoung Kim IET 2015 IET COMMUNICATIONS Vol.9 No.17

<P>In this study, the authors propose a joint iterative detection and decoding (JIDD) method for a turbo coded multiple-input multiple-output (MIMO) system, with a linear order of complexity. Accurate estimation of soft information should be conditioned for excellent performance of the JIDD, but it usually requires an exponential order of complexity. They propose a method which improves the performance of soft interference cancellation minimum mean-squared error (SIC-MMSE) method by increasing the reliability of the soft information utilised for interference cancellation. The proposed method utilises a posteriori probabilities from the MIMO detector as well as a priori probabilities from the turbo decoder, and perform soft minimum mean-squared error filtering for symbol level detection. With this approach, soft information is fully fed into the symbol detection process, and thus the reliability of soft symbol is increased. In addition, they can separate out the bit-level soft estimation process by using a simple linear method. Simulation results show that the proposed method provides substantial complexity reduction, with a bit error rate performance comparable to the conventional SIC-MMSE methods.</P>

Link scheduling schemes with on-off interference map for device-to-device communications

Jin-Whan Kang,Hussain, Ayaz,Sang-Hyo Kim IET 2015 IET COMMUNICATIONS Vol.9 No.3

<P>New distributed link scheduling schemes based on a recently proposed device-to-device (D2D) communication technology, FlashLinQ are studied. FlashLinQ is an orthogonal frequency division multiplexing-based synchronous D2D communication system, which achieves a high data rate at longer communication ranges over a licensed spectrum. In this method, some links are selected for data traffic for efficient frequency reuse to avoid interference in D2D links. Where every link is assigned a scheduling priority, so in TX (transmitter) and RX (receiver) yielding, the links which are highly interfered by higher priority links give up communication. However, this technique causes inefficiency in the resource reuse from the cascade yielding problem because link scheduling is performed individually by its RX and TX nodes. To deal with this problem, the authors propose two new link scheduling schemes based on a binary matrix called on-off interference map (I-Map), which indicates strong interference between links. In these schemes, each TX generates a binary I-Map matrix with the collective information from TX and RX blocks. With the common I-Map matrix that displays inter-link interference between D2D links, the proposed schemes achieve better performance as compared to the conventional distributed FlashLinQ scheduling scheme.</P>

Small-area and high-inductance semi-stacked spiral inductor with high Q factor

Ukaegbu, I. A.,Choi, K-S,Hidayov, O.,Sangirov, J.,Lee, T-W,Park, H-H IET 2012 IET microwaves, antennas & propagation Vol.6 No.8

<P>In this study, the authors describe the characterisation of spiral inductors and the design of a novel semi-stacked spiral inductor based on low-temperature co-fired ceramics (LTCC). Owing to its semi-stacked nature, the authors obtained a peak quality factor (<I>Q</I><SUB>max</SUB>) of 43.3 and an effective inductance <I>L</I><SUB>eff</SUB> of 14.41 nH. The authors LTCC spiral inductor occupies a smaller area when compared with conventional LTCC planar inductors of similar number of turns.</P>

Efficient list-sphere detection scheme for joint iterative multiple-input multiple-output detection

Ahmed, Saleem,Sooyoung Kim IET 2014 IET COMMUNICATIONS Vol.8 No.18

<P>List-sphere detection (LSD) is a sub-optimal multiple-input multiple-output (MIMO) detection scheme which searches candidate symbol vectors that lie within a sphere of a given radius. This study presents an efficient LSD based method for a joint iterative MIMO detection scheme. The proposed method utilises a channel condition in order to define the list size. During the search process, the radius is adaptively updated to reduce the computational complexity. Owing to the list size and corresponding radius are adaptively determined by the channel condition, the authors can operate the detector at the most appropriate complexity to produce the required performance. Simulation results show that the proposed methods provide substantial complexity reduction without bit error rate performance degradation.</P>

Cardiac disorder classification by heart sound signals using murmur likelihood and hidden markov model state likelihood

Kwak, C.,Kwon, O-W IET 2012 IET signal processing Vol.6 No.4

<P>This study proposes a new algorithm for cardiac disorder classification by heart sound signals. The algorithm consists of three steps: segmentation, likelihood computation and classification. In the segmentation step, the authors convert heart sound signals into mel-frequency cepstral coefficient features and then partition input signals into S1/S2 intervals by using a hidden Markov model (HMM). In the likelihood computation step, using only a period of heart sound signals, the authors compute the HMM `state` likelihood and murmur likelihood. The `state` likelihood is computed for each state of HMM-based cardiac disorder models, and the murmur likelihood is obtained by probabilistically modelling the energies of band-pass filtered signals for the heart pulse and murmur classes. In the classification step, the authors decided the final cardiac disorder by combining the state likelihood and the murmur likelihood by using a support vector machine. In computer experiments, the authors show that the proposed algorithm greatly improve classification accuracy by effectively reducing the classification errors for the cardiac disorder categories where the temporal murmur position plays an important role in detecting disorders.</P>

Finite-time reliable ℒ2 − ℒ ∞ /ℋ ∞ control for Takagi-Sugeno fuzzy systems with actuator faults

Park, Ju H.,Shen, Hao,Wu, Zheng-Guang IET 2014 IET CONTROL THEORY AND APPLICATIONS Vol.8 No.9

<P>This study deals with the problem of finite-time reliable L2 - L-infinity/H-infinity control for non-linear systems with actuator faults through Takagi-Sugeno fuzzy model approach. The actuator failure model under consideration is assumed to be governed by a homogenous Markov chain. The focus is on the design of a fuzzy Markov switching fault-tolerant controller such that the resulting closed-loop system is stochastically finite-time bounded with a mixed L2 - L-infinity/H-infinity performance level over a finite-time interval. Some sufficient conditions for the solvability of the above problem are given in terms of linear matrix inequalities by introducing a new mixed L2 - L-infinity/H-infinity performance function. Finally, a quarter-vehicle suspension model is employed to demonstrate the effectiveness of our proposed approach.</P>

Signal detection technique for asynchronous filtered multi-tone modulation-based mesh systems

Seung-Min Shin,Joo-Hyung Choi,Chang-Hwan Park,Won-Young Yang,Yong-Soo Cho IET 2015 IET COMMUNICATIONS Vol.9 No.5

<P>In this study, the authors propose a signal detection technique of successive interference cancellation to reduce the effect of inter-symbol interference (ISI), which is caused by the time difference of arrivals among distributed nodes in an asynchronous wireless mesh network based on filtered multi-tone modulation. The proposed signal detection technique uses partial matrices of a transmission gain matrix to mitigate the ISI effect from the adjacent symbols. Under the assumption of perfect symbol time offset and channel estimation at each node, it is shown by simulation that the proposed technique can improve the bit error rate performance with lower complexity compared with the conventional technique.</P>

Latency bounded and energy efficient MAC for wireless sensor networks

Kim, E-J,Shon, T.,Park, J. J. H.,Kang, C-H IET 2012 IET COMMUNICATIONS Vol.6 No.14

<P>This study presents the design and performance evaluation of a latency bounded and medium access control (MAC) scheme (abbreviated to LB-MAC) for wireless sensor networks that require time-critical communication. LB-MAC provides the predictability for an end-to-sink data delivery time through the time division multiple access (TDMA) multi-channel transmission frame assignment considering the routing path of a tree network. In addition, it uses the traffic-based slot assignment mechanism at every transmission frame to achieve energy efficiency. The feasibility and effectiveness of LB-MAC is demonstrated through extensive simulation based comparisons with prior research.</P>

Output tracking control with enhanced damping of internal dynamics and its output boundedness for static synchronous compensator system

Lee, Y. O.,Han, Y.,Chung, C. C. IET 2012 IET control theory & applications Vol.6 No.10

<P>This study investigates an important and challenging problem in non-linear systems: achieving output tracking control with a tolerable error bound as well as providing enhanced damping control of the internal dynamics. This problem is solved by using a damping controller in an input-output linearised static synchronous compensator system. The controllability and observability analyses direct the authors how to determine the damping controller gain. The proposed controller provides improved damping for lightly damped internal dynamics with degraded but tolerable output tracking performance. Finding a parameter-dependent Lyapunov function for the zero dynamics of error dynamics proves the stability of the damped internal dynamics in the time-invariant and time-varying systems. Stability of the closed-loop system is established by designing a composite Lyapunov function and it ensures that the tracking error of the output, in the approximated input-output linearised system, remains within a specified bound. Through stability analysis, the damping controller and the desired reference trajectory providing uniform boundedness of tracking error in output can be designed.</P>

Multi-core platform for an efficient H.264 and VC-1 video decoding based on macroblock row-level parallelism

Lee, J.-Y,Lee, J.-J,Park, S M IET 2010 IET circuits, devices & systems Vol.4 No.2

<P>In order for the video decoding processing such as H.264 and VC-1 to be effective in multi-core environments, several kinds of parallelisms must be utilised. Here, a novel parallelisation methodology, macroblock row-level parallelism (MBRLP), of video decoding is presented. The ETRI multimedia processing core (EMC) and the ETRI multi-core platform (EMP) are proposed for adopting MBRLP. In terms of the scalability and utilisation of processing cores, MBRLP has advantages over other parallelisation strategies such as frame, slice and macroblock (MB)-level parallelism. The scalability can be easily achieved by just increasing the number of processing cores and applying homogeneous software design/optimisation techniques to each EMC. Instead of employing a dynamic MB-level scheduler, a hybrid approach is used, which is a two-stage functional pipelining combined with MBRLP. The hybrid approach of combining MBRLP and de-blocking pipelining can relieve the synchronisation and inter-processor communication overheads incurred by multicore decoding systems as well as run-time scheduler's overheads. As a result, the proposed parallelisation method and architectures can boost the performance with the efficiency of 83%. The proposed architecture consisting of six EMC clusters has the capability to process Dl (720 × 480) 30 fps real-time decoding at around 200 MHz. The same concept can be applied to full-HD (1920 × 1088) video decoding in this work. It can be found that as the number of processing cores increase, the performance improvement is enhanced almost linearly. The EMP consisting of four EMC clusters (eight cores), memories and other peripherals are prototyped on Xilinx Virtex4 XC4VL200 FPGA which is operating at 60 MHz.</P>