Downlink WCDMA bit error rate performance in indoor system applications

This paper investigates the issue of antenna pointing error in mobile directional antenna applications and its impact on bit error rate (BER) performance of the link. BER performance is investigated for a variety of postulated antenna characteristics in order to determine the sensitivity of BER performance to antenna pointing inaccuracies. The method employed uses motion dynamics derived from vehicular road course tests to determine power fade profiles for various antenna types as a function of antenna pointing accuracy. These power fade profiles are then used to characterize these channels as Rician multipath channels. Finally antenna pointing accuracy is mapped directly to link BER performance for an uncoded differential phase shift keying (DPSK) waveform. This study has found that this is a complex multi-dimensional problem. Power fades resulting from pointing inaccuracy generally deteriorate for larger antennas with narrow beamwidths. However, smaller antennas are more susceptible to multipath effects due to increased beamwidth. Results of this paper suggests that, contrary to what intuition might initially suggest, larger antennas with more narrow beamwidths may actually outperform smaller antennas in mobile applications

By combing Spatial modulation (SM) with the Amplify-and-forward (AF) cooperative communication, a cooperative SM scheme with AF (AF-SM) protocol is presented, and the corresponding Bit error rate (BER) performance is investigated. Based on the performance analysis, the error probability of antenna index estimation ( P a ) and the error probability of symbol estimation ( P d ), which constitutes the overall average BER, are derived, respectively. As a result, tightly approximate closedform expressions of P a and P d are attained, respectively. Using these expressions, the closed-form overall average BER is achieved. During the analysis, the computational complexity of AF-SM detector is also provided in terms of the complex addition and multiplication numbers. Besides, the asymptotic BER at high SNR and the corresponding diversity gain are further derived, and the resultant diversity gain of N r + 1 is obtained for the system with N r receive antennas. Simulation results show that our theoretical analysis is valid, and provides good performance evaluation method for cooperative SM system. Moreover, the BER performance can be effectively improved as N r increases due to higher diversity gain.

This paper focuses on the bit error rate (BER) performance of intelligent transportation communication system under multipath mobile frequency-selective channels. After presenting the theoretical BER performance formula of single carrier frequency domain equalization (SC-FDE) in the form of double integral, a closed-form approximate upper bound of BER performance was derived，as well as specific analytical expressions for approximate BER performance bounds under typical modulations. Analysis and simulation show that the derived approximate BER bound highly approaches the theoretical one. The bound also indicates that the research about the preferable equalization methods is still necessary.

In this letter, we investigate the idea of interference spreading and its effect on bit error rate (BER) performance in a cognitive radio network (CRN). The interference spreading phenomenon is caused because of the random allocation of subcarriers in an orthogonal frequency division multiplexing (OFDM)-based CRN without any spectrum-sensing mechanism. The CRN assumed in this work is of underlay configuration, where the frequency bands are accessed concurrently by both primary users (PUs) and secondary users (SUs). With random allocation, subcarrier collisions occur among the carriers of primary users (PUs) and secondary users (SUs), leading to interference among subcarriers. This interference caused by subcarrier collisions spreads out across multiple subcarriers of PUs rather than on an individual PU, therefore avoiding high BER for an individual PU. Theoretical and simulated signal to interference and noise ratio (SINR) for collision and no-collision cases are validated for M-quadrature amplitude modulation (M-QAM) techniques. Similarly, theoretical BER performance expressions are found and compared for M-QAM modulation orders under Rayleigh fading channel conditions. The BER for different modulation orders of M-QAM are compared and the relationship of average BER with interference temperature is also explored further.

Aa analytical approach is presented for modeling crosstalk and to evaluate the bit error rate (BER) performance in a wavelength division-multiplexing (WDM) network for link with optical cross connect (OXC) without wavelength converter. Factors that affect the magnitude of crosstalk in the OXC are investigated and parameters that play important role in determining magnitude of crosstalk and BER are identified. The effects of OXC induced crosstalk on the BER performance is evaluated at a bit rate of 10 Gb/s by optimizing different parameters.

A noble theoretical approach is presented to evaluate the bit error rate (BER) performance of an optical polarization division multiplexed (PDM) 4-multilevel quadrature amplitude modulation (4-QAM) transmission system under the combined influence of polarization mode dispersion (PMD) and group velocity dispersion (GVD) in a single mode fiber (SMF). The analysis is carried out considering a coherent homodyne receiver. The exact probability density function (pdf) fluctuation due to PMD and GVD is evaluated from its moments using a Monte-Carlo simulation technique. Average BER is evaluated by averaging the conditional BER over the pdf of the random phase fluctuation. BER performance results are evaluated for different system parameters. It is found that PDM 4-QAM coherent homodyne system doubles the data rate but suffers more power penalty than the 4-QAM system. Results show that for a BER of 10^-9 at DGD of 0.5T and GVD value of 1700 ps/nm the PDM 4-QAM system needs 2.21 dB more power than 4-QAM systems giving the leverage of doubling the data rate.

Intersymbol Interference (ISI) is one of the major bottlenecks in Molecular Communication via Diffusion (MCvD) systems resulting in degraded system performance. This paper first introduces two new families of linear channel codes to minimize the effect of ISI: linear Zero Pad Zero Start (ZPZS) and linear Zero Pad (ZP) codes, ensuring that every codeword is devoid of consecutive bit-1s. Subsequently, the ZPZS linear and ZP linear codes are combined to form a binary ZP code, aiming for a higher code rate compared to the linear ZP codes, which can be decoded with a simple Majority Location Rule (MLR) algorithm. Additionally, a linear Leading One Zero Pad (LOZP) code is proposed, which relaxes the zero padding constraints considering the placement of bit-1s in the codeword as an important metric to have an improved code rate than the ZP code. Finally, a closed-form expression is deduced to compute the expected ISI for the proposed codes and to demonstrate that the expected ISI is a function of the average bit-1 density of the codewords in a code. To compare the ISI and BER performance with average bit-1 density of the proposed codes, two types of MCvD channel are considered: (i) channel without refresh, where the previously transmitted bits persist for a longer duration and (ii) channel with refresh, where the channel is cleared after each successful reception of the message. The ISI comparison, across different sequence distributions for a given length and weight, shows that the linear LOZP code exhibits superior resilience against ISI in a channel with refresh due to the placement of bit-1s at the initial positions, whereas the ZP code performs better in channel without refresh by reducing the average bit-1 density of the code. The asymptotic upper bound of the code rate is derived for the proposed codes, which depicts that a trade-off exists between the ISI and code rate. The simulation results show that the proposed family of ZP and linear LOZP codes can improve the Bit Error Rate (BER) performance by controlling the bit-1 locations and the average bit-1 density of the code, specifically where the ISI is more pronounced over the channel noise, thus providing a better reliability compared to the conventional error correcting codes at different data rate regimes.

This paper presents a bit error rate (BER) performance analysis of vehicular communication systems (VCS) based on the IEEE 802.11p standard assuming velocity variations of the mobile stations (MSs). To that end, we propose a novel Monte Carlo vehicle-to-vehicle (V2V) fading channel simulator that takes into account the accelerated motion and trajectory variations of the MSs. On the grounds of the proposed channel simulator, we assess the impact of the MSs' velocity variations on the system's BER performance. We assume that the channel state information is obtained following the least-squares (LS) channel estimation techniques that are commonly implemented in commercial off-the-shelf WiFi devices. The results show that the velocity variations have in general a slight impact on the system's BER performance. However, the performance is aggravated as the data frame length or the relative speed increases. The simulation framework presented in this paper can be used as a benchmark to evaluate the performance of the emerging VCS in safety critical scenarios.

An affine projection (AP)-based equalizer (APE) is introduced to eliminate the inter-symbol interference (ISI) for faster-than-Nyquist (FTN) signaling. Based on the APE, a pre-equalized interference cancellation (PIC) algorithm is proposed to eliminate the ISI for FTN signaling. By utilizing interference factors in the FTN system and low complexity APE, the computational complexity of the proposed PIC algorithm is much lower than the most existing block-based estimation algorithms, which makes it more practical for implementation. Besides, the proposed PIC algorithm has higher estimation accuracy by comparison with most existing algorithms. The simulation results show that the APE has a satisfactory bit error rate (BER) performance in the moderate ISI cases. In uncoded FTN systems, for all the modulation types adopted in digital video broadcasting-satellite-second generation extension (DVB-S2X), the proposed PIC algorithm can approximate the BER performance of the ISI-free Nyquist signaling when the time acceleration parameter and rolling factor equal to 0.8 and 0.3, respectively, which is beyond the performance of the most existing low-complexity algorithms. Even for 256-amplitude phase shift keying (APSK), the BER performance degradation is no more than 0.05 dB when the BER is 10 -5 . Furthermore, compared with the state-of-the-art frequency-domain equalization algorithm, the proposed PIC algorithm performs well in coded FTN systems.

In this paper, we introduce a 2-D non-isolated pixel modulation code to mitigate the problem of 2-D inter-symbol interference, the major obstacle of holographic data storage systems. The proposed modulation code does not allow a pixel to be isolated from its adjacent bits. We compare the bit error rate (BER) performance between the proposed and the conventional 6/8 balanced modulation codes. The proposed code shows better BER performance than that of the conventional 6/8 balanced code in a poor channel environment, such as large blur and misalignments.

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can significantly improve the downlink bit error rate (BER) performance of DS-CDMA in a frequency-selective fading channel. However, the uplink BER performance degrades due to a strong multi-user interference (MUI). We have proposed frequency-interleaved single-carrier spread spectrum multi-access (SC-SSMA) with MMSE-FDE, in which the subcarrier components of each user's signal are interleaved onto a wider bandwidth. Since frequency-interleaving patterns assigned to different users are orthogonal to each other, frequency-interleaved SC-SSMA can avoid the MUI completely while achieving frequency diversity gain with MMSE-FDE. In this paper, transmit/receive antenna diversity is applied to frequency-interleaved SC-SSMA with MMSE-FDE to further improve the BER performance. Its conditional BER is derived for the given set of channel gains. The average BER performance is numerically evaluated using the derived conditional BER and is confirmed by computer simulation.

End-to-end learning of a communications system using the deep learning-based autoencoder concept has drawn interest in recent research due to its simplicity, flexibility and its potential of adapting to complex channel models and practical system imperfections. In this paper, we have compared the bit error rate (BER) performance of autoencoder based systems and conventional channel coded systems with convolutional coding (CC), in order to understand the potential of deep learning-based systems as alternatives to conventional systems. From the simulations, autoencoder implementation was observed to have a better BER in 0-5 dB E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> range than its equivalent half-rate convolutional coded BPSK with hard decision decoding, and to have only less than 1 dB gap at a BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> . Furthermore, we have also proposed a novel low complexity autoencoder architecture to implement end-to-end learning of coded systems in which we have shown better BER performance than the baseline implementation. The newly proposed low complexity autoencoder was capable of achieving a better BER performance than half-rate 16-QAM with hard decision decoding over the full 0-10 dB E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> range and a better BER performance than the soft decision decoding in 0-4 dB E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> range.

This paper seeks to determine the Bit Error Rates (BER) performance for feasible free space optical communication (FSOC) deployment in Namibian and South African atmospheric weather conditions. In order to achieve this objective, the Pulse Position Modulation (PPM) based BER performance model was invoked to compute various BER values in selected towns of both countries. The results showed that in winter season, BER values were generally lower than in summer season. A comparative analysis for various towns with the lowest and the highest scintillation in both countries showed that BER increases rapidly as photon count increases in towns with high scintillation index values. The BER values realized from this study could be used to simulate internet traffic QoS advantages of the FSOC links when compared to the RF technology networks. The study outcomes are likely to benefit operators, industry, regulators, governments, and researchers in understanding feasible areas of FSOC deployment in both countries.

In free space optical (FSO) communication systems, atmospheric turbulence is the major cause of bit error rate (BER) performance degradation. The error performance of the system can be significantly improved with the help of spatial diversity by employing multiple transmit or receive apertures. However, correlation of channels under turbulence in the case of small separation between transmit apertures can substantially reduce the benefits of spatial diversity. Still, a thorough analysis of the system performance in terms of diversity order and coding gain for the FSO multiple-input single-output (MISO) system under turbulence influenced correlated channels has not been studied when the repetition coding is used to achieve improved BER performance. In this paper, we provide unique results of the BER performance analysis of the considered correlated FSO-MISO system over Gamma–Gamma distributed turbulence channel. Using the joint moment generating function of received signal-to-noise ratio (SNR), a novel generalized approximate BER expression is derived, followed by convergence test of the power series based BER expression using the Cauchy's ratio test. Then, an asymptotic analysis at high SNR is performed to obtain a novel closed-form expression for BER of FSO-MISO system. We also derive expressions for coding gain, diversity gain, and coding gain loss due to correlation in channels. Although the effect of correlation in channels on the BER performance of the system is analyzed under different scenarios, while it is observed that it does not affect the diversity order; it significantly degrades the coding gain of the considered system.

Effect of atmospheric turbulence on the BER performance of an optical CDMA FSO link with SIK receiver