Capacity of systems using single modulation type can be calculated in a semi-deterministic fashion. However, for systems with adaptive modulation and coding, the capacity is also dependent on the distribution of modul...
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Capacity of systems using single modulation type can be calculated in a semi-deterministic fashion. However, for systems with adaptive modulation and coding, the capacity is also dependent on the distribution of modulations and traffic beneath these distributions. In order to utilise the network resources effectively, the areas with higher traffic should be covered with higher order modulation that can provide higher throughput levels. In this work, an optimization metric is proposed for utilization of the systems with adaptive modulations. The proposed metric, by making use of the coverage areas of specific modulations and the traffic demand beneath them; will be an important tool in the optimization procedures of systems that support multi-level modulations such as 3G and 4G.
3GPP LTE is the evolution of UMTS which will make possible to deliver next generation high quality multimedia services according to the users' expectations. The flexibility of the downlink OFDM radio interface wit...
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ISBN:
(纸本)9781424451227
3GPP LTE is the evolution of UMTS which will make possible to deliver next generation high quality multimedia services according to the users' expectations. The flexibility of the downlink OFDM radio interface with Adaptive modulation and coding (AMC), MIMO and H-ARQ plays a crucial role in achieving the low latency and high spectral efficiency promised by the new radio access standard. This paper presents a LTE DL link level simulator whose main purpose is to generate suitable look-up tables to interface with a system level simulator. In this context, the Exponential Effective SIR (EESIR) metric is a link abstraction model that is used to properly characterize multistate channels. The reference BLER curves in AWGN channel and the parameters of the EESIR model are given for the complete list of CQI's specified for LTE DL. The obtained results also include curves of mean link level throughput for different AMC formats and MIMO configurations.
In this contribution, an adaptive underwater acoustic modem with high bandwidth and power efficiency is proposed. Key features include interleave-division multiplexing (IDM) in time and frequency domain (and optionall...
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In this contribution, an adaptive underwater acoustic modem with high bandwidth and power efficiency is proposed. Key features include interleave-division multiplexing (IDM) in time and frequency domain (and optionally in the spatial domain) in conjunction with generalized (non-orthogonal) multi-carrier (MC) transmission. IDM is a special form of superposition coded modulation. At the receiver side, joint intersymbol interference (ISI) and adjacent channel interference (ACI) cancellation is performed, in addition to iterative decoding. Adaptation (with respect to variable data rates, variable signal power, variable signal bandwidth, variable range, variable channel conditions, variable service requirements, etc.) is supported to an extend, which is currently unknown in the area of underwater communications. The communication signal can be used for navigation/positioning purposes without modification at the transmitter side. The system design is easily applicable in underwater networks, and extendable to an arbitrary number of transducers (MIMO processing). The modem is implemented by means of software-defined radio. A wide range of potential applications is targeted.
In this paper, performance of binary pulse position modulation-time hopping (BPPM-TH) and the binary pulse amplitude modulation-direct sequence (BPAM-DS) ultra wide band (UWB) systems with a double binary turbo code i...
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In this paper, performance of binary pulse position modulation-time hopping (BPPM-TH) and the binary pulse amplitude modulation-direct sequence (BPAM-DS) ultra wide band (UWB) systems with a double binary turbo code is analyzed and simulated in an indoor wireless channel. The indoor wireless channel is modeled as a modified Saleh and Valenzuela (SV) channel. The performance is evaluated in terms of bit error probability (BER). From the simulation results, it is seen that double binary turbo coding offers considerable coding gain with reasonable encoding complexity. It is also demonstrated that the performance of the UWB system can be substantially improved by increasing the number of iterations.
Receivers for horizontally encoded LTE based MIMO-OFDM systems are considered in this paper. Adaptive modulation and coding (AMC) is used as well as precoding. The linear minimum mean square error (LMMSE), successive ...
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ISBN:
(纸本)9781424458257
Receivers for horizontally encoded LTE based MIMO-OFDM systems are considered in this paper. Adaptive modulation and coding (AMC) is used as well as precoding. The linear minimum mean square error (LMMSE), successive interference cancellation (SIC) and K-best list sphere detectors (LSD) are compared. The receivers were designed and implemented for 2×2 and 4×4 antenna systems and meet the decoding rate requirement in LTE, i.e, 210 Mb/s in 2×2 and 405 Mb/s in 4×4 antenna systems. The results show that the performance of the receivers is similar in low SNR but the performance difference increases when a higher rank transmission is used. The K-best LSD has the highest performance and complexity. A simpler receiver could be used in the low SNRs to save power and a more complex receiver in the high SNRs when a higher goodput is needed.
This paper proposes a near-capacity yet simple bit-interleaved coded modulation with iterative decoding (BICM-ID) scheme by employing a multi-dimensional (multi-D) mapping technique in a multi-D constellation carved f...
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This paper proposes a near-capacity yet simple bit-interleaved coded modulation with iterative decoding (BICM-ID) scheme by employing a multi-dimensional (multi-D) mapping technique in a multi-D constellation carved from a rotated lattice. Using extrinsic information transfer (EXIT) charts, it is shown that the proposed technique fits well with simple convolutional codes in terms of the area property, for which turbo pinch-off can happen at a low E b /N 0 value. In particular, both EXIT chart analysis and simulation results indicate that by using just a simple convolutional code together with a 4-D mapping, a turbo pinch-off and a bit error rate (BER) close to 10 -6 happen at a signal-to-noise ratio (SNR) that is even lower than the BICM constraint capacity limit with a uniform input. The proposed BICM-ID scheme can be considered as an attractive alternative to other bandwidth-efficient coded modulation techniques using powerful turbo-like codes such as turbo or low-density parity-check (LDPC) codes over a Rayleigh fading channel.
A kind of signal processing method combing autocorrelation detection and FM harmonic detection technology is presented for the radio ranging system based on pseudo-random binary-phase code and linear frequency combine...
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A kind of signal processing method combing autocorrelation detection and FM harmonic detection technology is presented for the radio ranging system based on pseudo-random binary-phase code and linear frequency combined modulation. The mathematic model of ranging system is studied. The virtual simulation model for ranging system is established and the ranging property is analyzed. The simulation results of ranging resolution are consonant with the calculation values. The results are addressed that the ranging method has excellent ranging precision.
In this paper we considered jointly optimised source and channel decoding, while employing serially concatenated and iteratively decoded Short Block Codes (SBC) combined with a Unity Rate Code (URC) and multi-dimensio...
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In this paper we considered jointly optimised source and channel decoding, while employing serially concatenated and iteratively decoded Short Block Codes (SBC) combined with a Unity Rate Code (URC) and multi-dimensional Sphere Packing (SP) modulation. The resultant coded signal is transmitted over non-coherently detected Multiple-Input Multiple-Output (MIMO) Differential Space-Time Spreading (DSTS) designed for near capacity joint source-channel decoding (JSCD). The performance of the system was evaluated by considering interactive video telephony using the H.264/AVC source codec. The source coded parameters generated by the state-of-the-art H.264/AVC video codec typically contain limited natural residual redundancy. Therefore, to improve the error robustness of iterative sourcechannel decoding (ISCD), SBCs are incorporated to impose artificial redundancy on the source coded parameters. The natural residual redundancy after source coding and the artificial redundancy due to SBC coding is iteratively exploited in a turbo process to improve the overall Bit Error Ratio (BER) and objective video quality performance quantified in terms of the Peak Signal to Noise Ratio (PSNR). The convergence behaviour of the advocated MIMO transceiver is investigated with the aid of Extrinsic Information Transfer (EXIT) charts. The proposed system exhibits an E b /N 0 gain of about 22 dB at the PSNR degradation point of 2 dB in comparison to the benchmarker scheme carrying out DSTS aided SP-demodulation as well as iterative source and channel decoding, when using I system = 5 system iterations, while communicating over correlated narrowband Rayleigh fading channels.
An enhanced adaptive scheme based on threshold method with a reduced complexity that combine adaptive modulation and coding with diversity combining is presented for throughput maximization in broadband code division ...
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An enhanced adaptive scheme based on threshold method with a reduced complexity that combine adaptive modulation and coding with diversity combining is presented for throughput maximization in broadband code division multiple access (CDMA) satellite networks. The proposed algorithm is a modify, enhanced, and more robust version of the existing algorithms for adaptive transmission rate and modulation in CDMA networks. The rate compatible punctured turbo-coded (RCPT), which has been found to give improved throughput performance in a direct sequence (DS) CDMA is exploited. A semi-analytical process and simulations were carried out. It is found that there are significant improvement in the average throughput and the bit-error performance. The proposed algorithm using adaptive coding and modulation (instead of variable spreading gain) outperforms other systems such as Selective Power Control with Active Link Protection (SPC-ALP) algorithm proposed for adaptive transmission rate and power control in CDMA networks.
Quantization index modulation (QIM) is a commonly used data hiding technique where a single bit is embedded per coefficient. Here, we propose the use of double embedding in the QIM framework where a single coefficient...
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Quantization index modulation (QIM) is a commonly used data hiding technique where a single bit is embedded per coefficient. Here, we propose the use of double embedding in the QIM framework where a single coefficient is modified twice, using two quantizers, to embed two bits. The motivation behind substituting single embedding with double embedding in the QIM framework for a certain steganographic scheme is to increase its hiding rate without significantly increasing the embedding distortion and the stego scheme's detectability against steganalysis. We empirically determine the best way to couple the double embedding framework with a repeat accumulate code based error correction scheme. For moderate noise levels, the use of double embedding is seen to be significantly advantageous over single embedding.
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