Towards Fully Optimized BICM Transceivers

Experimental measurements have shown that the noise in many communication channels is non-Gaussian. Bit interleaved coded modulation (BICM) is very popular for spectrally efficient transmission. Recent results have shown that the performance of BICM using convolutional codes in non-fading channels can be significantly improved if the coded bits are not interleaved at all. This particular BICM design is called BICM trivial (BICM-T). In this paper, we analyze the performance of a generalized BICM-T design for communication over Gaussian mixture noise (GMN) channels. The results disclose that for an optimal bit error rate (BER) performance, the use of an interleaver in BICM for GMN channels depends upon the strength of the impulsive noise components in the Gaussian mixture. The results presented for 16-QAM show that the BICM-T can result in gains up to 1.5 dB for a target BER of 10 -6 if the impulsive noise in the Gaussian mixture is below a certain threshold level. The simulation results verify the tightness of developed union bound (UB) on BER performance.

Recently, the differential detection scheme has attracted considerable attention as a demodulated scheme for digital mobile communications because of its robustness in the frequency nonselective fading channel. A problem of the differential detection scheme is that its bit error rate (BER) performance in the additive white Gaussian noise (AWGN) channel is inferior to that of the coherent detection scheme. To solve this problem, many methods to improve BER performance of the differential detection in the AWGN channel have been proposed. However, those methods require complex signal processings.This paper proposes a novel differential detection scheme as a simpler improvement method which estimates the differential phase of the transmitted signal by a sequence estimation scheme using the Viterbi algorithm. The proposed scheme is simplified in a manner such that its signal processing is composed of only additions and subtractions on the phase information of the received signal. Results of computer simulation show that BER performance of the proposed scheme is close to that of the ideal coherent detection in the AWGN channel. In addition, the trellis diagram of the Viterbi algorithm can be reduced without performance degradation introducing the signal processing similar to the Scarece State Transition (SST) type Viterbi decoding. The proposed scheme also is useful in the case of the fast Rician fading channel and the slow Rayleigh fading channel.

Hierarchical constellations offer a different degree of protection to the transmitted messages according to their relative importance. As such they found interesting application in digital video broadcasting systems as well as wireless multimedia services. Although a great deal of attention has been devoted in the literature to the study of the bit error rate (BER) performance of uniform phase shift keyed (PSK) constellations, very few results were published on the BER performance of hierarchical PSK constellations. We obtain exact and generic expressions in M for the BER of the generalized hierarchical M-PSK constellations over additive white Gaussian noise (AWGN) and fading channels. For the AWGN case, these expressions are in the form of a weighted sum of Pawula (1982) F-functions and are solely dependent on the constellation size M, the carrier-to-noise ratio, and a constellation parameter which controls the relative message importance. Because of their generic nature, these new expressions readily allow numerical evaluation for various cases of practical interest.

The combination of multiple-input multiple-output (MIMO) and bit-interleaved coded modulation (BICM)/BICM with iterative demapping (BICM-ID) is one of the key technologies to meet the high-transmission-rate requirement of the next generation broadcasting systems. However, conventional low-density parity check (LDPC) coded MIMO BICM schemes always show poor performance with iterative demapping, and vice versa. In this paper, a subset of spatially coupled codes, finite-length spatially coupled (SC-) quasi-cyclic (QC-) LDPC code, is proposed and the universality of spatially coupled codes is utilized to achieve a good tradeoff between MIMO BICM and BICM-ID schemes. Due to the specific code structure of SC-QC-LDPC, the tool of multi-edge type density evolution (MET-DE) is employed for the performance analysis and code optimization. As an example, a finite-length SC-QC-LDPC code is optimized in binary-input additive white Gaussian noise channel, and then bit error rate simulations are carried out to verify the universality of the designed code in MIMO BICM and BICM-ID schemes.

This paper investigates linear precoding for bit-interleaved coded modulation (BICM) on additive white Gaussian noise (AWGN) channels. Concatenating a linear precoder as an inner encoder with an outer (convolutional) encoder produces a powerful code with a limited decoding complexity. Linear precoders are examined and optimized for two scenarios: using (i) a noniterative decoding strategy and (ii) an iterative decoding strategy under a perfect feedback assumption. The precoder design is based on an information-theoretical approach, on the one hand, and a pair-wise error probability (PEP) analysis, on the other hand. Both approaches render convenient precoder design rules. For a binary phase-shift keying (BPSK) signal set, the optimal precoders that result from these rules are also derived. Numerical results confirm the analytical findings and simulations illustrate the effectiveness of the approach.

The optical ZCZ code, which is a set of pairs of binary and biphase sequences with zero correlation zone, can provide code division multiple access (CDMA) communication system without co-channel interference. The M-ary amplitude shift keying spread spectrum (M-ary/ASK-SS) system using this code can detect a desired sequence without interference of undesired sequences. We have proposed the compact construction of a matched filter bank for this code, which is called the compact-type matched filter bank. However, M-ary/ASK-SS system using this filter bank might go down the bit error rate (BER) performance because input-output characteristics of this filter bank for this code with zero correlation zone 4n - 2 are nonlinear characteristics. In this paper, we clarify that BER performance in the M-ary/ASK-SS system over the additive white Gaussian noise (AWGN) channels is not influenced by nonlinear characteristics of this filter bank by the theoretical formula of BER characteristics and the computer simulation. The BER performance in the ASK-SS system using compact-type matched filter under the AWGN environment go down compared to that using direct-type matched filter as expected. But the BER performance in the M-ary/ASK-SS system using this compact-type matched filter bank under the AWGN environment is almost equal compared to that using parallel-type matched filter bank. In fact, this compact-type matched filter bank is effective in the M-ary/ASK-SS system.

Data rate increase in global navigation satellite systems (GNSS) is necessary to provide new features (e.g. precise positioning, security code authentication (SCA) key management). In addition, the data transmission reliability in urban environments can be improved using an induced increase of temporal diversity; the latter being obtained by retransmitting data bits thanks to the data rate improvement. The code shift keying (CSK) modulation is a solution for augmenting data rates of direct-sequence spread-spectrum (DSSS) signals. In addition, last developed GNSS signals make use of modern channel codes in order to further improve the reliability of GNSS data recovery. Hence, this article aims at proposing new binary low-density parity-check (LDPC) codes constructed for the CSK modulation in a bit-interleaved coded modulation (BICM) context. Codes achieving good error rate performance for both BICM and BICM with iterative demapping/decoding (BICM-ID) are presented. The code construction methodology is detailed and the good performance achieved by the constructed codes is assessed in additive white Gaussian noise (AWGN) channel.

The Orthogonal Frequency Division Multiplexing (OFDM) is also known as multicarrier technology. Wideband digital communications in the recent past have increasingly utilized OFDM. It can withstand difficult channel circumstances, efficiently utilize spectrum resources, decrease ISI, and operate at a high data rate, among many other benefits. It has been used in several wireless and wired communication systems, including fourth generation Long-Term Evolution (4G LTE) mobile communications. The performance assessment and analysis of the OFDM system under Additive White Gaussian Noise (AWGN) channel has been carried out in this work. The factors in which system performance is assessed include the signal quality, Bit Error Rates (BERs), and Signal to Noise Ratios (SNRs) of the received signals. To improve performance while employing multicarrier modulation, the subcarriers must be kept orthogonal to one another, in the process known as OFDM. The sole focus of this study is the performance analysis of PAPR, BER, and SNR utilizing various modulation methods and schemes.

The use of open-loop coding can be easily extended to a closed-loop concatenated code if the transmitter has access to feedback. This can be done by introducing a feedback transmission scheme as an inner code. In this paper, this process is investigated for the case when a linear feedback scheme is implemented as an inner code and, in particular, over an additive white Gaussian noise (AWGN) channel with noisy feedback. To begin, we look to derive an optimal linear feedback scheme by optimizing over the received signal-to-noise ratio (SNR). From this optimization, a linear feedback scheme is produced that is asymptotically optimal in the sense of blocklength-normalized SNR; it is then compared to other well-known schemes. Then, the linear feedback scheme is implemented as an inner code to a concatenated code over the AWGN channel with noisy feedback. This code shows improvements not only in error exponent bounds, but also in bit error rate (BER) and frame error rate (FER). It is also shown that if the concatenated code has total blocklength L and the inner code has blocklength, N, the inner code blocklength should scale as N = O(C/R), where C is the capacity of the channel and R is the rate of the concatenated code. Simulations with low-density parity-check (LDPC) and turbo codes are provided to display practical applications and their error rate benefits.

Coding Schemes for Energy Constrained IoT Devices

Multiple trellis coded modulation of constant envelope frequency and phase modulated signal sets (MTCM/FPM) is investigated for performance on the additive white Gaussian noise (AWGN) channel and on the one-sided normal, Rayleigh and Rician fading channels. The Nakagami-m fading model is used as an alternative to the Rician fading model to calculate the error probability upper bound for trellis-coded schemes on the fading channel. The likeliness and the disparity between the upper bounds to the error probability for the two fading models are discussed. The design criteria for the one-sided normal fading channel, modeled by the Nakagami-m distribution, are observed to be the same as those for the Rayleigh-fading channel. For the MTCM/FPM schemes, it is demonstrated that the set partitioning designed to maximize symbol diversity (optimum for fading channels) is optimum for performance on the AWGN channel as well. The MTCM/FPM schemes demonstrate improved performance over MTCM/MPSK schemes and TCM/FPM schemes on the AWGN channel and the fading channel.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper examines the bit error rate (BER) of a direct sequence spread spectrum (SS) system that uses bandlimited white Gaussian noise (BLWGN) as a spreading code. The performance of this bandlimited-SS system is examined in both additive white Gaussian noise (AWGN) and single tone jamming environments. The BLWGN spreading code is inferior to conventional codes in AWGN channels, but is more robust when a narrow band interference signal is present.

In this paper, the performance of the Dual Hop relaying systems is studied and analyzed. Differential Amplify-and-Forward is the used relaying scheme. Post-Detection Selection combining reception technique was proposed to achieve the cooperative diversity where No explicit channel estimation is needed. Instead, the receiver uses the previous received sample in each branch as the estimate of the current fading gain in that branch. The exact outage probability of the system over additive white Gaussian noise and Nakagami-m fading channels is derived assume independent fading in the channels. Simulation results are plotted for different fading parameters.

We analyze the effect of a nonlinearity on the bit error rate performance of multicarrier spread spectrum (MCSS) systems in the presence of multipath fading. A 5th order polynomial model is used to represent the amplifier amplitude nonlinearities (AM/AM) and a flat Rayleigh fading channel is assumed for each modulated carrier. It is found that for the additive white Gaussian noise and multipath fading channel, the bit error degradation from a nonlinear amplification is not as significant as in the additive white Gaussian noise channel alone.

The UMTS Long Term Evolution (LTE) is an emerging technology in the evolution of 3G networks. LTE runs on an advancement of the obtainable UMTS infrastructure already used by over 80 percent of mobile subscribers worldwide. We have very inadequate resources in cellular technologies and it is important to utilize them with high efficiency. Single Carrier Frequency Division Multiple Access (SC-FDMA) & Orthogonal Division Multiple Access (OFDMA) are most important division of LTE. OFDMA was well utilized for achieving high spectral efficiency in communication method. SC-FDMA is introduced in recent times and it became handy candidate for uplink multiple access scheme in LTE system that is a project of Third Generation Partnership Project (3GPP). The Multiple Access Scheme in Advanced Mobile radio system has to meet the challenging requirements for example high throughput, fine robustness, capable Bit Error Rate (BER), high spectral efficiency, small delays, low computational difficulty, less Peak to Average Power Ratio (PAPR), low error probability etc. In our paper, we investigate the performance of SC-FDMA in LTE physical layer by considering different modulation schemes (QPSK, 16QAM and 64QAM) on the basis of BER vs Eb/No. Additive White Gaussian Noise (AWGN) and fading channel are used to evaluate the performance in presence of noise and fading.