Parallel Quadrature Index Modulation with Transmit Diversity in Large MIMO Systems

In this article, the performance of M-ary phase shift keying (PSK) modulation schemes over mobile-to-mobile (M2M) fading channels with equal gain combining (EGC) in cooperative networks is analyzed. Narrowband M2M fading channels under line-of-sight (LOS) propagation conditions are modeled as double Rice processes. A dual-hop amplify-and-forward relay network, where LOS components can exist in the transmission links between the source mobile station and the destination mobile station via K mobile relays, is studied. Here, the average bit error probability (BEP) is utilized to evaluate the performance of Mary PSK modulation schemes. A simple analytical approximation for the average BEP of M-ary PSK modulations over relay-based M2M fading channels with EGC is derived. The accuracy of the approximation is assessed by simulations. The presented results show that in a dual-hop relay system with EGC, the presence of LOS components in the relay links improves the systems' performance. In addition, a significant enhancement in the diversity gain can be achieved as the number of diversity branches K increases.

In recent years, conveying information using molecules via diffusion has attracted significant interest in micro and nanoscale applications. Yet, very little research have been conducted on the performance analysis of large-scale molecular communication (MC) systems with swarm of interfering receivers. In this type of MC system, the collective signal strength at a desired receiver can be impaired by the interference caused by other MC transmitters. The paper presents the first tractable analytical framework for the collective signal strength at a partially absorbing receiver due to a desired transmitter under the impact of a swarm of interfering transmitters in a three-dimensional (3D) large-scale MC system using stochastic geometry. We propose Reed Solomon (RS) coding as an error correction technique to combat the effects of interference caused by the multiple transmitters and the delayed molecules from the previous bits. We derive analytical expressions for the bit error probability (BEP) to evaluate the level of reliability that can be achieved by the proposed scheme. The results obtained using Monte Carlo simulations, matched extactly with the anlytical results, justifying the accuracy of the derivations. Results reveal that the RS codes are capable of providing an acceptable level of improvement in terms of BEP. Furthermore, by carefully selecting the code length, n, and the message length, k, of the RS(n, k) code, we can fine tune the BEP improvement to match the system requirements.

Orthogonal frequency division multiplexing with index modulation (OFDM-IM), which transmits information bits via <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$ </tex-math></inline-formula> -ary constellation symbols and indices of the active subcarriers, is a promising OFDM-based multicarrier transmission scheme. Recently, several new schemes have been proposed by utilizing the flexibility of the OFDM-IM to meet the diverse needs of 5G networks. Coordinate interleaved OFDM-IM (CI-OFDM-IM) that conveys the real and imaginary part of the data symbols over different subcarriers and OFDM with power distribution IM (OFDM-PIM) that transmits the data symbols over high and low power subcarriers, are two OFDM-IM based schemes with additional diversity gain and improved bit error rate (BER) performance. In this letter, we propose a novel transmission scheme named as coordinate interleaved OFDM with power distribution IM (CI-OFDM-PIM), which applies coordinate interleaving and power distribution in subcarriers to achieve a higher diversity gain. The average bit error probability (ABEP) for the CI-OFDM-PIM is derived and the superior error performance of the proposed scheme over benchmarks are shown via computer simulations.

This paper presents coded differential TR (cDTR) receiver that transmits extra bit by mapping information in K different orthogonal codes. The performance of the coded DTR is analyzed and compared with the conventional DTR. Throughout the analysis, the performance of receivers in terms of bit error probability (BEP), data rate and receiver complexity are assessed. The results show that coded DTR is able to outperform conventional DTR receiver in terms of data rate maintaining the same BEP. Additionally, the receiver hardware complexity issue is discussed

In previous work, we studied the structure and performance of optimum maximum-likelihood receivers for binary antipodal and orthogonal signals in the presence of Gaussian-distributed channel estimation error and additive white Gaussian noise for flat Rayleigh fading channels. In this paper, we investigate the structure and performance of these receivers for an application where Gaussian-distributed channel estimation error arises: minimum mean-square error channel estimation in quasi- static Rayleigh fading channels. Exact closed-form analytical expressions are derived for the average bit error probability (BEP). We quantify the impact of number of pilot symbols in each frame as well as the ratio of the power of the pilot symbol to the power of data on the average BEP. We derive conditions under which orthogonal signalling results in a lower average BEP compared with binary antipodal signalling.

The performance of a multicarrier direct sequence code division multiple access (MC-DS-CDMA) system in fading environment has been extensively analysed in the literatures. The analysis that is available in the literatures did not take into account the impact of jamming and channel estimation errors on the performance of the system. In this study, closed-form expressions of the average bit error probability (BEP) of the MC-DS-CDMA system with channel estimation errors in the presence of partial band, broadband and multitone jamming are derived in a Rayleigh fading channel. The analysis shows that the magnitude of the normalised correlation between the actual and the estimated complex fading channel gain, A, greatly affects the performance of the MC-DS-CDMA system. For large signal-to-noise ratio, the average BEP with A=1 and without multiple access interference (MAI) tends to zero. When A≠1, the BEP of the system exhibits an error floor even without MAI. This error floor increases as the number of users increases. It is also shown that increasing the number of the system subcarriers enhances the system performance against jamming.

A principal component combining with differential detector (PCC–DD) is proposed to demodulate M-ary DPSK signals in diversity systems. Exact average bit error probability (BEP) of binary DPSK signals over Rayleigh fading channels for the PCC–DD is obtained in closed form and is shown to agree with the results of simulations. Approximate average BEP of quadrature and octal DPSK signals over Rayleigh fading channels for the PCC–DD are also derived and are shown to be close to those from simulations. It is also shown that PCC–DD outperforms the well known DPSK demodulator that contains a set of differential detectors followed by equal gain combining (DD–EGC) over Rayleigh fading channels in terms of low-average BEP. The performance gain of the PCC–DD over the DD–EGC is large when the signal is binary DPSK, and is very small when the signal is either quadrature or octal DPSK.

Wireless communications has become one of the fastest growing areas in our modern life and creates enormous impact on nearly every feature of our daily life. In this paper, the performance of M-ary modulations schemes (MPSK, MQAM, MFSK) based wireless communication system on audio signal transmission over Additive Gaussian Noise (AWGN) channel are analyzed in terms of bit error probability as a function of SNR. Based on the results obtained in the present study, MPSK and MQAM are showing better performance for lower modulation order whereas these are inferior with higher M. The BER value is smaller in MFSK for higher M, but it is worse due to the distortion in the reproduce signal at the receiver end. The lossless reproduction of recorded voice signal can be achieved at the receiver end with a lower modulation order.

In this paper, we investigate the performance of the Viterbi decoding algorithm with/without Automatic Repeat reQuest (ARQ) over a Rician flat fading channel with unlimited interleaving. We show that the decay rate of the average bit error probability with respect to the bit energy to noise ratio is at least equal to d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> at high-bit energy to noise ratio for both cases (with ARQ and without ARQ), where d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> is the free distance of the convolutional code. The Yamamoto-Itoh flag helps to reduce the average bit error probability by a factor of 4(d) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> with a negligible retransmission rate. We also prove an interesting result that the average bit error probability decays exponentially fast with respect to the Rician factor for any fixed bit energy per noise ratio. In addition, the average bit error exponent with respect to the Rician factor is shown to be d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> .

We analyze the average bit error probability (BEP) of orthogonal space-time block codes (STBC) over time-selective channels. Exact BEP results are obtained in closed form. Through the analysis, we reveal the relationship between the inter-symbol interference (ISI) and the row positions in a STBC matrix. We then introduce one proposition and two design criteria for code search/design. Optimum/near-optimum codes are found/designed with reduced ISI.

This paper investigates pilot symbol-assisted channel estimation in multiple-input multiple-output orthogonal frequency division multiplexing systems. Especially, under multipath fading channels, we perform the analysis for optimal pilot spacing that maximizes the effective data rate which represents the number of correctly detected data per unit time. To do this, we first find the statistical properties of the estimated effective channel including interpolation error. After that, utilizing the statistical properties of the estimated effective channel, the average bit error probability and the effective data rate according to the pilot spacing are derived. Furthermore, based on the derived results, we obtain the average optimal pilot spacing to maximize the effective data rate of the systems. In simulation results, we verify analysis for the average bit error probability and effective data rate by comparing analytical and simulation results according to the frequency selectivity of the channel models. The existence of optimal pilot spacing which compromises the average bit error probability and data rate is also confirmed by the analytical results of the effective data rate. Finally, we discuss the relationship between the frequency selectivity of the channels and optimal pilot spacing, and the effectiveness of utilizing average optimal pilot spacing in practical channel models. Simulation results show that, regardless of the frequency selectivity of the channels, the average optimal spacing can achieve at least 93% of maximum effective data rate performance except for the case of the bottom 5%.

The performance of generalized selection combining (GSC) space diversity for mobile radio systems in the presence of multiple cochannel interferers is studied. Two cochannel interference models are considered: (1) L cochannel interferers consisting of L-N Nakagami-m (1960) interferers and N Rayleigh interferers and (2) L cochannel interferers in which each interferer follows Nakagami-m distribution for a fraction of time and Rayleigh distribution for the remaining of time. The fading parameters of the Nakagami-m interferers are limited to integer values only. The desired signal is assumed to be Rayleigh faded. Also, all the desired signals and the cochannel interferers received on each branch are independent of each other. Closed-form expressions are derived for the probability density functions (PDFs) of the instantaneous signal-to-interference power ratio (SIR) at the output of the GSC for the two cochannel interference models. Using these SIR PDFs, closed-form expression for evaluating the outage probability and the average bit error probability (BEP) are subsequently derived. A differential phase-shift keying scheme is considered in the derivation. Numerical results showing the influences of various system parameters on the outage probability and the average BEP are then presented.

An efficient network is critical to support the rapid growth in traffic on mobile networks, since current network PCS1900 (2G) cannot support such a huge demand. The objective of the third-generation (3G) UMTS (Universal Mobile Telecommunication System) of wireless communication is to provide high speed wireless communication to support multimedia, large data, and video. However, the co-existence of the two mobile radio systems (PCS1900 and UMTS) which share the same frequency band leads to a major issue. A serious issue of co-existence occurs when the downlink of the system is closer to the frequency bands of the concerned system. The PCS-1900 downlink band (1,930-1,990) and WCDMA (UMTS) uplink band (1,920-1,980) widely overlap, which causes interference between UMTS mobile unit and PCS-1900 base station. Therefore the objectives of this paper is to study the effect from PCS 1900 base station interference on UMTS mobile unit performance in terms of the probability of bit error by developing the Probability of bit error equation of DSS-QPSK from the existing Probability of bit error equation. This paper also evaluates the degradation of UMTS mobile unit performance in terms of probability of bit error when the system is interfered by PCS1900 base station.

The use of codes in forward error correction and decision feedback schemes is analysed. Various comparisons of the two types of error control scheme are undertaken when finite and infinite repetitions are possible and when the feedback channel can be considered noisy or noiseless. These comparisons are based on the consideration of both the average information bit error probability and transmission efficiency to obtain the overall effectiveness of the error control schemes.

Permutation index-quadrature spatial modulation: A spectral efficient spatial modulation for next generation networks