286 research outputs found
Burst-by-Burst Adaptive Turbo-Coded Radial Basis Function-Assisted Decision Feedback Equalization
No full textThe performance of the proposed radial basis function (RBF) assisted turbo-coded adaptive modulation scheme is characterized in a wideband channel scenario. We commence by introducing the novel concept of the Jacobian RBF equalizer, which is a reduced-complexity version of the conventional RBF equalizer. Specifically, the Jacobian logarithmic RBF equalizer generates its output in the logarithmic domain and hence it can be used to provide soft outputs for the turbo-channel decoder. We propose using the average magnitude of the log-likelihood ratio (LLR) of the bits in the received transmission burst before channel decoding as the channel quality measure for controlling the mode-switching regime of our adaptive scheme
Space-Time Trellis and Space-Time Block Coding Versus Adaptive Modulation and Coding Aided OFDM for Wideband Channels
No full textAbstract—The achievable performance of channel coded spacetime trellis (STT) codes and space-time block (STB) codes transmitted over wideband channels is studied in the context of schemes having an effective throughput of 2 bits/symbol (BPS) and 3 BPS. At high implementational complexities, the best performance was typically provided by Alamouti’s unity-rate G2 code in both the 2-BPS and 3-BPS scenarios. However, if a low complexity implementation is sought, the 3-BPS 8PSK space-time trellis code outperfoms the G2 code. The G2 space-time block code is also combined with symbol-by-symbol adaptive orthogonal frequency division multiplex (AOFDM) modems and turbo convolutional channel codecs for enhancing the system’s performance. It was concluded that upon exploiting the diversity effect of the G2 space-time block code, the channel-induced fading effects are mitigated, and therefore, the benefits of adaptive modulation erode. In other words, once the time- and frequency-domain fades of the wideband channel have been counteracted by the diversity-aided G2 code, the benefits of adaptive modulation erode, and hence, it is sufficient to employ fixed-mode modems. Therefore, the low-complexity approach of mitigating the effects of fading can be viewed as employing a single-transmitter, single-receiver-based AOFDM modem. By contrast, it is sufficient to employ fixed-mode OFDM modems when the added complexity of a two-transmitter G2 scheme is affordable
Turbo-Coded Adaptive Modulation Versus Space-Time Trellis Codes for Transmission over Dispersive Channels
No full textDecision feedback equalizer (DFE)-aided turbocoded wideband adaptive quadrature amplitude modulation (AQAM) is proposed, which is capable of combating the temporal channel quality variation of fading channels. A procedure is suggested for determining the AQAM switching thresholds and the specific turbo-coding rates capable of maintaining the target bit-error rate while aiming for achieving a highly effective bits per symbol throughput. As a design alternative, we also employ multiple-input/multiple-output DFE-aided space–time trellis codes, which benefit from transmit diversity and hence reduce the temporal channel quality fluctuations. The performance of both systems is characterized and compared when communicating over the COST 207 typical urban wideband fading channel. It was found that the turbo-coded AQAM scheme outperforms the two-transmitter space–time trellis coded system employing two receivers; although, its performance is inferior to the space–time trellis coded arrangement employing three receivers. Index Terms—Coded adaptive modulation, dispersive channels, space–time trellis codes
Systematic redundant residue number system codes: analytical upper bound and iterative decoding performance over AWGN and Rayleigh channels
No full textThe novel family of redundant residue number system (RRNS) codes is studied. RRNS codes constitute maximum–minimum distance block codes, exhibiting identical distance properties to Reed–Solomon codes. Binary to RRNS symbol-mapping methods are proposed, in order to implement both systematic and nonsystematic RRNS codes. Furthermore, the upper-bound performance of systematic RRNS codes is investigated, when maximum-likelihood (ML) soft decoding is invoked. The classic Chase algorithm achieving near-ML soft decoding is introduced for the first time for RRNS codes, in order to decrease the complexity of the ML soft decoding. Furthermore, the modified Chase algorithm is employed to accept soft inputs, as well as to provide soft outputs, assisting in the turbo decoding of RRNS codes by using the soft-input/soft-output Chase algorithm. Index Terms—Redundant residue number system (RRNS), residue number system (RNS), turbo detection
A Burst-by-Burst Adaptive Joint-Detection Based CDMA Speech Transceiver
No full textA burst-by-burst adaptive speech transceiver is proposed, which can drop its source coding rate and speech quality under transceiver control in order to invoke a more error resilient modem mode amongst less favourable channel conditions. The novel, high-quality, Adaptive Multi-Rate (AMR) speech codec [5], operated at bit rates of 4.75 and 10.2 kbps and combined with sourcesensitivity-matched Redundant Residue Number Systems (RRNS) based channel codes. Burst-by-burst adaptive Joint-Detection based Code-Division Multiple Access (JDCDMA) is used for transmitting the dual-rate bitstream generated by the AMR speech codec
Everettia safriei Liew & Schilthuizen & Vermeulen 2009, SP. NOV.
No full textEVERETTIA SAFRIEI SP. NOV. Types: MALAYSIA: State of Sabah: Ranau District. Southern part of Kinabalu Park. At 2300 m alt. along Kotal’s route from Bukit Babi to the eastern ridge of Mount Kinabalu (6°3 ′ N, 116°36 ′ E). Collected by T.- S. Liew, J. Lapidin, Safrie, and Jasilin. 24.iv.2005, holotype, BOR/MOL 5307, Figure 12D; six paratypes, three in BMNH 20080631 and three in SP 13063. Etymology: This species is named after Safrie Hatimin, staff member at Kinabalu Park, who dedicatedly assisted the first author during the intensive malacological survey on Mount Kinabalu in 2005. Material examined: SABAH – Mount Kinabalu: BOR/ MOL 2671, southern slope, 3330 m alt., x.2003; BOR/ MOL 2672, southern slope, 3330 m alt., x.2003; BOR/MOL 2682, southern slope, 3080 m alt., x.2003; BOR/MOL 2683, southern slope, 3080 m alt., x.2003; BOR/MOL 2687, southern slope, 3080 m alt., x.2003; BOR/MOL 5302, southern slope, 3024 m alt., ix.2005; BOR/MOL 5306, southern slope, 3089 m alt., xii.2004; BOR/MOL 5303, eastern slope, 3264 m alt., vi.2005; BOR/MOL 5304, eastern slope, 3352 m alt., vi.2005; BOR/MOL 5305, eastern slope, 3432 m alt., vi.2005; BOR/MOL 5308, eastern slope, 3416 m alt., vi.2005; BOR/MOL 5309, eastern slope, 2924 m alt., iv.2005; BOR/MOL 5310, eastern slope, 3336 m alt., vi.2005. Diagnostic characteristics: The numerous, irregular, very fine, and discontinuous spiral threads on the upper surface of the shell differentiate this species from individuals of Everettia dominiki with similar shell shape and size. Description: Shell (Figs 10C, 12D): small, rather thin, greenish brown, moderately elevated, outer whorls rounded. Periphery rounded; spire almost flat. Above the periphery, protoconch smooth (sometimes with inconspicuous, densely placed spiral threads); shell with distinct oblique wrinkling; there are very fine, irregular and discontinuous spiral threads above the wrinkling. Below the periphery, shell is almost smooth. Height up to 4.8 mm; width up to 8.3 mm; diameter of the first three whorls 0.75–0.8, 0.55–0.60, and 0.95–1.00 mm, respectively; number of whorls up to five and one-quarter; height aperture up to 3.6 mm; width aperture up to 4.5 mm. Genitalia (Fig. 13C): maximum length from genital opening to the end of dart-sac (before the visible gland tubules) up to 4.5 mm. The penis, dart-sac, and vagina with very thin transparent walls. P, V, GO, BC, and DS arranged around the short genital atrium, with limited space between the openings of each of the genital structures. BC short, about half of total DS length. Animal (Fig. 8D): the head of animal head is uniformly black. The mantle is brownish and in the last half whorl has sparse irregular black and bright markings. Distribution and habitat: Upper montane primary and coniferous forest, 2700–3500 m alt. Sabah: Mount Kinabalu (eastern and southern ridges only), endemic (Fig. 9A). Remarks: This species occurs sympatrically with E. safriei, to which it is also phylogenetically close. However, both species maintain their distinct and unique shell characteristics.Published as part of Liew, Thor-Seng, Schilthuizen, Menno & Vermeulen, Jaap Jan, 2009, Systematic revision of the genus Everettia Godwin-Austen, 1891 (Mollusca: Gastropoda: Dyakiidae) in Sabah, northern Borneo, pp. 515-550 in Zoological Journal of the Linnean Society 157 (3) on page 540, DOI: 10.1111/j.1096-3642.2009.00526.x, http://zenodo.org/record/544302
Turbo Equalization of Convolutional Coded and Concatenated Space Time Trellis Coded Systems using Radial Basis Function Aided Equalizers
No full textIn this contribution a reduced-complexity radial basis function (RBF) aided neural-network based turbo equalization (TEQ) scheme is proposed for employment in a serially concatenated convolutional coded and systematic space time trellis coded (CC-SSTTC) arrangement. A two-path Rayleigh fading channel having a normalised Doppler frequency of 3.3615 x l0E-05 was used. The BER performance of the RBF-CC-SSTTC(4,4) scheme employing a transmission burst consisting of 100 symbols using a space-time-trellis (STT) interleaver of at least 400 symbols and eight turbo equalization iterations was found to be similar to that of the CC-SSTTC system using a trellis-based TEQ, which attains the optimum performance. However, the Jacobian RBF based TEQ provided a complexity reduction factor of 14
Everettia dominiki Liew & Schilthuizen & Vermeulen 2009, SP. NOV.
No full textEVERETTIA DOMINIKI SP. NOV. <p> <i>Types:</i> MALAYSIA: State of Sabah: Kota Marudu District. North-eastern part of Kinabalu Park. At 1600 m alt. along the trail from Serinsim Substation to Mount Nombuyukon No (6°15 <i>′</i> N, 116°40 <i>′</i> E). Collected by T.- S. Liew. Date: 9.xi.2005, holotype, BOR/ MOL 5360, Figure 12C; six paratypes, three in BMNH 20080635 and three in SP 13067.</p> <p> <i>Etymology:</i> This species is named after Dominik Tinggoh, staff member at Kinabalu Park, who dedicatedly assisted the first author during the intensive malacological survey on Mount Kinabalu in 2005.</p> <p> <i>Material examined:</i> SABAH – Mount Kinabalu: BOR/ MOL 1314, southern slope, 1450 m alt., vi.2002; BOR/ MOL 2691, southern slope, 2865 m alt., x.2003; BOR/MOL 2697, southern slope, 2267 m alt., x.2003; BOR/MOL 2698, southern slope, 2460 m alt., x.2003; BOR/MOL 5380, southern slope, 2112 m alt., iv.2005; BOR/MOL 5381, southern slope, 2404 m alt., iv.2005; BOR/MOL 5383, southern slope, 2096 m alt., ix.2005; BOR/MOL 5385, southern slope, 2628 m alt., iv.2005; BOR/MOL 5386, southern slope, 2288 m alt., iv.2005; BOR/MOL 5388, southern slope, 2308 m alt., xii.2004; BOR/MOL 5390, southern slope, 2526 m alt., xii.2004; BOR/MOL 5392, southern slope, 2552 m alt., ix.2005; BOR/MOL 5396, southern slope, iv.2006; BOR/MOL 5399, southern slope, 3154 m alt., i.2005; BOR/MOL 5400, southern slope, 2896 m alt., ix.2005; BOR/MOL 5401, southern slope, 3024 m alt., ix.2005; BOR/MOL 5402, southern slope, 2896 m alt., xii.2004; BOR/MOL 5403, southern slope, 3088 m alt., ix.2005; BOR/MOL 5405, southern slope, 2528 m alt., iv.2005; BOR/ MOL 5408, southern slope, 1948 m alt., iv.2005; BOR/ MOL 5410, southern slope, 2092 m alt., iv.2005; BOR/MOL 5412, southern slope, 2040 m alt., iv.2005; BOR/MOL 5413, southern slope, 2120 m alt., iv.2005; BOR/MOL 5414, southern slope, 2120 m alt., iv.2005; BOR/MOL 5417, southern slope, 1784 m alt., ix.2005; BOR/MOL 5419, southern slope, 2484 m alt., xii.2004; BOR/MOL 5398, western slope, 2640 m alt., ix.2005; BOR/MOL 5409, western slope, 1968 m alt., ix.2005; BOR/MOL 5422, western slope, 2576 m alt., ix.2005; BOR/MOL 5387, eastern slope, 2812 m alt., iv.2005; BOR/MOL 5389, eastern slope, 2676 m alt., iv.2005; BOR/MOL 5391, eastern slope, 2132 m alt., iv.2005; BOR/MOL 5404, eastern slope, 1992 m alt., iv.2005; BOR/MOL 5411, eastern slope, 1952 m alt., iv.2005; BOR/MOL 5387, eastern slope, 2812 m alt., iv.2005; BOR/MOL 5415, eastern slope, 2300 m alt., iv.2005; BOR/ MOL 5416, eastern slope, 3112 m alt., iv.2005; BOR/ MOL 5418, eastern slope, 2992 m alt., iv.2005; BOR/MOL 5420, eastern slope, 3064 m alt., iv.2005; BOR/MOL 5421, eastern slope, 2188 m alt., iv.2005; BMNH 20080208, southern slope, Mesilau, vi.1967; BMNH 20080209, southern slope, Mesilau, vi.1967. Mount Tambuyukon: BOR/MOL 5383, eastern slope, 2288 m alt., ix.2005; BOR/MOL 5384, eastern slope, 2080 m alt., ix.2005; BOR/MOL 5395, eastern slope, ix.2005; BOR/MOL 5397, eastern slope, 1584 m alt., ix.2005; BOR/MOL 5406, eastern slope, 1952 m alt., ix.2005; BOR/MOL 5407, eastern slope, 3260 m alt., ix.2005.</p> <p> <i>Diagnostic characteristics:</i> Shell surface with dense and regularly radial ribs.</p> <p> <i>Description:</i> Shell (Figs 3F, 12C): medium-sized, rather thin, brownish, spire moderately to highly elevated, outer whorls shouldered below the suture. Periphery rounded. Above the periphery, shell silky with fine, dense, and regular radial corrugation, <i>c.</i> 20 wrinkles per mm. Below the periphery, shell has corrugation that extends from above the periphery and dense shallow spiral grooves, but some individuals with only faded spiral grooves on the bottom surface of the shell or entirely without these. Height up to 8.3 mm; width up to 10.1 mm; diameter of the first three whorls 0.7, 0.9, and 1.2 mm, respectively; number of whorls up to four and a half; height aperture up to 4.7 mm; width aperture up to 5.5 mm. Genitalia (Fig. 13B): maximum length from genital opening to the end of dart-sac (before the visible gland tubules) up to 7 mm. The penis and dart-sac have thin muscular walls but vagina has a very thin transparent wall. P, V, GO, BC, and DS arranged around the short genital atrium, with limited space between the opening of each of the genital structures. BC long, almost as long as DS. Animal (Fig. 8C): black bands on either side of the tentacles, which are separated by a white band that occupies the space between the eye tentacles and extends backward to the end of the mantle and downward to the foot fringe. However, in a few rare cases the animal’s head is uniformly black. Other parts of the animal are almost entirely black. Some blackish smears and bright markings are irregularly arranged on the brownish mantle. The mantle in the last half whorl is covered by sparse, irregular black and bright markings.</p> <p> <i>Distribution and habitat:</i> Montane primary forest 1500–3300 m (common). Sabah: Mount Kinabalu (endemic?) (Fig. 9C).</p> <p> <i>Remarks:</i> The two morphs of this species – with and without spiral grooves on the underside of the shell, occur sympatrically but the one with these spiral grooves can mainly be found between 2000–2500 m. However, genetic data do not support the monophyly of these two morphs.</p>Published as part of <i>Liew, Thor-Seng, Schilthuizen, Menno & Vermeulen, Jaap Jan, 2009, Systematic revision of the genus Everettia Godwin-Austen, 1891 (Mollusca: Gastropoda: Dyakiidae) in Sabah, northern Borneo, pp. 515-550 in Zoological Journal of the Linnean Society 157 (3)</i> on pages 542-543, DOI: 10.1111/j.1096-3642.2009.00526.x, <a href="http://zenodo.org/record/5443023">http://zenodo.org/record/5443023</a>
Reduced Complexity In-phase/Quadrature-phase Turbo Equalisation Using Radial Basis Functions
No full textA novel reduced complexity Radial Basis Function (RBF) neural network based equaliser, referred to as the In-phase/Quadrature-phase RBF Equaliser (I/Q-RBF-EQ), is proposed. The I/Q-RBF-EQ is employed in the context of turbo equalisation (TEQ) assisted by iterative channel estimation. The performance of the I/Q-RBF-TEQ is characterized in a noise limited environment over an equally weighted, symbol-spaced three-path Rayleigh fading channel. The I/Q-RBF-TEQ achieved the same performance as the conventional turbo equaliser, while achieving a complexity reduction by a factor of 1.5 and 109.6 for 4-QAM and 16-QAM, respectively
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