Generalized Low-Density Parity-Check Coding Aided Multilevel Codes

Classic Low-Density Parity-Check (LDPC) codes have recently been used as component codes in Multilevel Coding (MLC) due to their impressive BER performance as well as owing to their flexible coding rates. In this paper, we proposed a Multilevel Coding invoking Generalized Low-Density Parity-Check (GLDPC) component codes, which is capable of outperforming the classic LDPC component codes at a reduced decoding latency, when communicating over AWGN and uncorrelated Rayleigh fading channels

Serially Concatenated Luby Transform Coding and Bit-Interleaved Coded Modulation Using Iterative Decoding for the Wireless Internet

In Bit-Interleaved Coded Modulation (BICM) the coding and modulation schemes were jointly optimized for the sake of attaining the best possible performance when communicating over fading wireless communication channels. The iterative decoding scheme of BICM (BICM-ID) invoking an appropriate bit-to-symbol mapping strategy enhances its achievable performance in both AWGN and Rayleigh channels. BICM-ID may be conveniently combined with Luby Transform (LT) codes, which were designed for handling packetized wireless Internet data traffic in erasure channels without retransmitting the corrupted packets. By jointly designing a serially concatenated LT-BICM-ID code, an infinitesimally low Bit Error Rate (BER) is achieved for Signal to Noise Ratios (SNR) in excess of 7.5dB over wireless Internet type erasure channels contaminated by AWGN

Three-Dimensional EXIT Chart Analysis of Iterative Detection Aided Coded Modulation Schemes

The iterative convergence of iteratively detected coded modulation schemes having different block lengths, decoding complexity and an unequal error protection capability is studied, when communicating over AWGNchannels using 8PSK modulation. More specifically, the coded modulation schemes investigated include Multilevel Coding (MLC), Trellis Coded Modulation (TCM), Turbo Trellis Coded Modulation (TTCM), Bit-Interleaved Coded Modulation (BICM) as well as Bit-Interleaved Coded Modulation employing Iterative Decoding (BICM-ID). A novel three dimensional EXIT chart was introduced for studying the iterative convergence behaviour of the Multistage Decoding (MSD) scheme used in MLC

Multilevel Generalised Low-Density Parity-Check Codes

Multilevel coding invoking generalised low-density parity-check component codes is proposed, which is capable of outperforming the classic low-density parity check component codes at a reduced decoding latency

Downlink Steered Space-Time Spreading Assisted Generalised Multicarrier DS-CDMA Using Sphere-Packing-Aided Multilevel Coding

This paper presents a novel generalised Multi-Carrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system invoking smart antennas for improving the achievable performance in the downlink, as well as employing multi-dimensional Sphere Packing (SP) modulation for increasing the achievable diversity product. In this contribution, the MC DS-CDMA transmitter considered employs multiple Antenna Arrays (AA) and each of the AAs consists of several antenna elements. Furthermore, the proposed system employs both time- and frequency- (TF) domain spreading for extending the achievable capacity, when combined with a novel user-grouping technique for reducing the effects of Multiuser Interference (MUI). Moreover, in order to further enhance the system’s performance, we invoke a MultiLevel Coding (MLC) scheme, whose component codes are determined using the so-called equivalent capacity based constituent-code rate-calculation procedure invoking a 4-dimensional bit-to-SP-symbol mapping scheme. Our results demonstrate an approximately 3.8 dB Eb/N0 gain over an identical throughput scheme dispensing with SP modulation at a BER of 10?5

Equivalent-Capacity-Based Design of Space-Time Block-Coded Sphere-Packing-Aided Multilevel Coding

A multilevel coding (MLC) scheme invoking sphere packing (SP) modulation combined with space time block coding (STBC) is designed. The coding rates of each of the MLC component codes are determined using the so-called equivalent capacity based constituent-code rate-calculation procedure invoking a 4-dimensional (4D) sphere packing bit-to-symbol mapping scheme. Four different-rate Low-Density Parity Check (LDPC) constituent-codes are used by the MLC scheme. The performance of the resultant equivalent capacity based design is characterized using simulation results. Our results demonstrate an approximately 3.5dB gain over an identical scheme dispensing with SP modulation. Furthermore although a similar performance gain is attained by both the proposed MLC scheme and its benchmarker, which uses a single-class LDPC code, the MLC scheme is preferred, since it benefits from the new classic philosophy of using low-memory, low-complexity component codes as well as providing an unequal error protection capability

Luby Transform Coding Aided Bit-Interleaved Coded Modulation for the Wireless Internet

Bit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Transform (LT) coding. The resultant joint design of the physical and data link layer substantially improves the attainable Bit Error Rate (BER) performance. A Cyclic Redundancy Check (CRC) combined with a novel Log-Likelihood Ratio (LLR) based packet reliability estimation method is proposed for the sake of detecting and disposing of erroneous packets. Subsequently, bit-by-bit LT decoding is proposed, which facilitates a further BER improvement at a lower number of BICM-ID iterations. Finally, we revisit the pseudo random generator function used for designing the LT generator matrix

Precoder-Aided Iterative Detection Assisted Multilevel Coding and Three-Dimensional EXIT-Chart Analysis

A novel three-dimensional (3D) EXIT chart is developed for investigating the iterative behaviour of Multilevel Coding (MLC) invoking Multistage Decoding (MSD). The extrinsic information transfer characteristics of both the symbol-to-bit demapper used and those of the differentprotection constituent decoders suggest that potential improvements can be achieved by appropriately designing the demapper. The proposed 3D EXIT chart is then invoked for studying the precoder-aided multilevel coding scheme employing both MSD and Parallel Independent Decoding (PID) for communicating over AWGN and uncorrelated Rayleigh fading channels with the aid of 8PSK modulation. At BER=10?5, the precoder was capable of enhancing the achievable Eb/N0 performance by 0.5dB to 2.5dB over AWGN and Rayleigh channels, respectively

Assessing statistical significance of periodogram peaks

The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is used routinely in many branches of astronomy to search for periodicities in observational data. The problem of assessing statistical significance of candidate periodicities for different periodograms is considered. Based on results in extreme value theory, improved analytic estimations of false alarm probabilities are given. They include an upper limit to the false alarm probability (or a lower limit to the significance). These estimations are tested numerically in order to establish regions of their practical applicability.Comment: 7 pages, 6 figures, 1 table; To be published in MNRA

Marketing System of Non-Timber Forest Products:-The Case of Palmyra Palm in North-Eastern Nigeria

This study investigated the marketing system of Palmyra Palm products in North-eastern Nigeria to; identify its marketable products, channels of distribution and roles of market participants, and also assess its marketing facilities in North-eastern Nigeria. Data were generated through market surveys and interviews on 203 respondents selected randomly from Adamawa, Bauchi and Yobe markets. The generated data were analysed using descriptive statistics where appropriate. Marketing system focusing market organization was analyzed qualitatively by observing the marketing channels, roles of market participants and marketing facilities. The results revealed that exchange and ownership of title to products occurred at the local markets (54.0%), farmers' homes (37.7%), and farmers' farms (6.2%), and inter-states' markets (2.1%). The marketing channel of Palmyra palm was highly decentralised and thus the marketing system was expected to be operationally efficient. However, because of poor road network, high transportation cost and poor marketing facilities, the marketing system was adjudged operationally inefficient. Market participants introduced flaws in the marketing system; farm-gate middlemen dominated marketing operations, commissioned buying agents over-depended on wholesalers for capital, and there was collusion in price determination. Marketing facilities namely market places, storage, processing, transportation and packaging were crude and inadequate, while credit facilities were virtually absent. To address these inadequacies, the study recommended provision of improved marketing facilities and communication gadgets, formation of consumer co-operative organizations to check the excesses of the middlemen in the market and more research into the marketing of Non-timber forest resources.&#160