5,226 research outputs found
Turbo-Detected Unequal Protection MPEG-4 Audio Transceiver Using Convolutional Codes, Trellis Coded Modulation and Space-Time Trellis Coding
No full textA jointly optimised turbo transceiver capable of providing unequal error protection is proposed for employment in an MPEG-4 aided audio transceiver. The transceiver advocated consists of Space-Time Trellis Coding (STTC), Trellis Coded Modulation (TCM) and two different-rate Non-Systematic Convolutional codes (NSCs) used for unequal error protection. A benchmarker scheme combining STTC and a single-class protection NSC is used for comparison with the proposed scheme. The audio performance of the both schemes is evaluated when communicating over uncorrelated Rayleigh fading channels. It was found that the proposed unequal protection turbo-transceiver scheme requires about two dBs lower transmit power than the single-class turbo benchmarker scheme in the context of the MPEG-4 audio transceiver, when aiming for an effective throughput of 2 bits/symbol, while exhibiting a similar decoding complexity
Turbo-detected unequal protection audio and speech transceivers using serially concatenated convolutional codes, trellis coded modulation and space-time trellis coding
No full textThe MPEG-4 TwinVQ audio codec and the AMR-WB speech codec are investigated in the context of a jointly optimised turbo transceiver capable of providing unequal error protection. The transceiver advocated consists of serially concatenated Space-Time Trellis Coding (STTC), Trellis Coded Modulation (TCM) and two different-rate Non-Systematic Convolutional codes (NSCs) used for unequal error protection. A benchmarker scheme combining STTC and a single-class protection NSC is used for comparison with the proposed scheme. The audio and speech performance of both schemes is evaluated, when communicating over uncorrelated Rayleigh fading channels. An value of about 2.5 (3.5)~dB is required for near-unimpaired audio (speech) transmission, which is about 3.07 (4.2)~dB from the capacity of the system
Iteratively Decoded Variable Length Space-Time Coded Modulation
No full textAn Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Nonbinary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discrete-valued source symbols are first encoded into variable-length codewords that are mapped to the spatial and temporal domains. Then the variable-length codewords are interleaved and fed to the precoded modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme contriving source coding, channel coding, modulation and spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is more than 14 dB better than that of the Fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4
Space-time block coded IQ-interleaved joint coding and modulation for AWGN and Rayleigh fading channels
No full textSpace-Time Block Coded (STBC) In-phase/Quadrature-phase (IQ)-interleaved Trellis Coded Modulation (TCM) and Turbo TCM (TTCM) schemes are proposed, which are capable of quadrupling the achievable diversity order of the conventional symbol-interleaved TCM and TTCM schemes, when two transmit antennas are employed. The increased diversity order of the proposed schemes provides significant additional coding gains, when communicating over non-dispersive Rayleigh fading channels, which is achieved without compromising the coding gain attainable over Gaussian channels. Bit-Interleaved Coded Modulation (BICM) as well as Iteratively Decoded BICM (BICM-ID) are also incorporated into the proposed system and their performance is compared to that to TCM and TTCM
Space-Time IQ-interleaved TCM and TTCM for AWGN and Rayleigh Fading Channels
No full textSpace-time block coded inphase-quadrature phase (IQ)-interleaved trellis coded modulation (TCM) and Turbo TCM (TTCM) schemes are proposed, which are capable of quadrupling the diversity order of conventional symbol-interleaved TCM and TTCM schemes. The increased diversity order of the proposed schemes provides significant coding gains, when communicating over non-dispersive Rayleigh fading channels without compromising the coding gain achievable over Gaussian channels
Irregular Convolution and Unity-Rate Coded Network-Coding for Cooperative Multi-User Communications
No full textNear-Capacity Multi-user Network-coding (NCMN) based systems operating in multiple modes and relying on an amalgamated Irregular Convolutional Code, a Unity-Rate Code and M-ary Phase-Shift Keying are proposed. We consider a multiuser network in which the users cooperatively transmit their independent information to a common base station (BS). Extrinsic Information Transfer (EXIT) charts were used for designing the proposed NCMN scheme for the sake of approaching the Discrete-input Continuous-output Memoryless Channel’s (DCMC) capacity. The NCMN systems are capable of simultaneously exploiting the advantages of all the new modes we designed for our system and those of the conventional mode. The design principles presented in this contribution can be extended to a vast range of NCMN based systems using arbitrary channel coding schemes
Slow subcarrier-hopped Space Division Multiple Access OFDM systems
No full textRecently Space Division Multiple Access (SDMA) assisted Multi-Input-Multi-Output (MIMO) OFDM systems invoking Multi-User Detection (MUD) techniques have attracted substantial research interests, which are capable of exploiting both transmitter multiplexing gain and receiver diversity gain. Furthermore, the classic Frequency-Hopping (FH) technique can be effectively amalgamated with SDMA-OFDM systems, resulting in Frequency-Hopped (FH) SDMA-OFDM. In this paper we devise a Turbo Trellis Coded Modulation (TTCM) assisted subcarrier-based FH/SDMA-OFDM scheme, which may be able to fully exploit the attainable frequency diversity, while exhibiting a high Multi-User-Interference (MUI) resistance. In the high-throughput scenario investigated, the proposed Uniform Slow-SubCarrier-Hopped (USSCH) SDMA-OFDM system was capable of achieving 6dB Eb=N0 gain at the BER of 10¡4 over the conventional SDMA-OFDM system, while maintaining a similar complexity
Full-Rate, Full-Diversity Adaptive Space Time Block Coding for Transmission over Rayleigh Fading Channels
No full textA full-rate, full-diversity Adaptive Space Time Block Coding (ASTBC) scheme based on Singular Value Decomposition (SVD) is proposed for transmission over Rayleigh fading channels. The ASTBC-SVD scheme advocated is capable of providing both full-rate and full-diversity for any number of transmit antennas, Nt, provided that the number of receive antennas, Nr, equals to Nt. Furthermore, the ASTBC-SVD scheme may achieve an additional coding gain due to its higher product distance with the aid of the block code employed. In conjunction with SVD, the “water-filling” approach can be employed for adaptively distributing the transmitted power to the various antennas transmit according to the channel conditions, in order to further enhance the attainable performance. Since a codeword constituted by Nt symbols is transmitted in a single time slot by mapping the Nt symbols to the Nt transmit antennas in the spatial domain, the attainable performance of the ASTBC-SVD scheme does not degrade, when the channel impulse response values vary from one time slot to the next. Hence, the proposed ASTBC-SVD scheme is attractive in the context of both uncorrelated and correlated Rayleigh fading channels. The performance of the proposed scheme was evaluated, when communicating over uncorrelated Rayleigh fading channels. Explicitly, an Eb/N0 gain of 2.5 dB was achieved by the proposed ASTBC-SVD scheme against Alamouti’s scheme [1], when employing Nt = Nr = 2 in conjunction with 8PSK
Space-Time Block Coded and IQ-interleaved TCM, TTCM, BICM and BICM-ID Assisted OFDM
No full textSpace-Time Block Coded (STBC) In-phase Quadrature-phase (IQ)-interleaved Coded Modulation (CM) schemes are proposed for Orthogonal Frequency Division Multiplexing (OFDM). Trellis Coded Modulation (TCM), TurboTCM(TTCM), Bit-Interleaved Coded Modulation (BICM) and Iteratively Decoded BICM (BICM-ID) schemes having a similar decoding complexity are employed in conjunction with 16-level Quadrature Amplitude Modulation (16QAM) for yielding an effective throughput of 3 information bits per symbol. The IQ-diversity attained by the proposed schemes provides a significant additional coding gain. It was found that TTCM and BICM-ID assisted STBC-IQ-OFDM were the best schemes in terms of the achievable bit error ratio and frame error ratio, respectively
Burst-by-burst Adaptive Joint-Detection CDMA/H.26L Based Wireless Video Telephony using TTCM and LDPC Codes
No full textA low bit-rate video coding techniques using the H.26L standard codec for robust transmission in mobile multimedia environments are presented. For the sake of achieving error resilience, the source codec has to make provisions for error detection, resynchronization and error concealment. Thus a packetization technique invoking adaptive bit-rate control was used in conjunction with the various modulation scheme employed. In this contribution, we propose a Burst-by-Burst Adaptive Coded Modulation-Aided Joint Detection-Based CDMA (ACM-JD-CDMA) scheme for wireless video telephony and characterise its performance when communicating over the UTRA wideband vehicular fading channels. The coded modulation schemes invoked in our fixed modulation mode based systems are Low Density Parity Check code based Block Coded Modulation (LDPC-BCM) and Turbo Trellis Coded Modulation (TTCM). The performance of LDPC-BCM was evaluated and compared to that of TTCM in the context of the ACM-JD-CDMA system using a practical modem mode switching regime. Both schemes exhibited a similar transmission integrity, although the LDPC arrangement is capable of achieving this at a lower complexity
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