Space diversity reception is well known as a technique that can improve the performance of wireless communication systems without any temporal and spectral resource expansion. Implant body area networks (BANs) require high-speed transmission and low energy consumption. Therefore, applying spatial diversity reception to implant BANs can be expected to fulfill these requirements. For this purpose, this paper presents a local frequency offset diversity system with π/4-differential quadrature phase shift keying (DQPSK) for implant BANs that offer improved communication performance with a simpler receiver structure, and evaluates the proposal's bit error rate (BER) performance by theoretical analysis. In the theoretical analysis, it is difficult to analytically derive the probability density function (pdf) on the combined signal-to-noise power ratio (SNR) at the local offset frequency diversity receiver output. Therefore, this paper adopts the moment generating function approximation method and demonstrates that the resulting theoretical analyses yield performances that basically match the results of computer simulations. We first confirm that the local frequency offset diversity reception can effectively improve the communication performance of implant BANs. Next, we perform an analysis of a realistic communication performance, namely, a link budget analysis based on derived BER performance and evaluate the link parameters including system margin, maximum link distance and required transmit power. These analyses demonstrate that the local frequency offset diversity system can realize a reliable communication link in a realistic implant BAN scenario.

In this letter, we investigate the performance of cooperative decode-and-forward multiple-input multiple-output relaying system using orthogonal space-time block codes with piecewise-linear (PL) receiver over correlated Nakagami-m fading channels for integer values of m. We derive the closed-form expression for the exact bit error rates of binary phase shift keying signals. The analytical expression is validated through numerical results. It is shown that the performance of PL receiver outperforms that of conventional maximal ratio combining receiver.

A multiuser precoding algorithm based on matching weighted signal-to-leakage-and-noise ratio (SLNR) is proposed for multiuser MIMO downlink systems. In the proposed algorithm, the matching weight factor is selected based on the effective channel gain, and the leakage power caused by each user is weighted by the factor. The precoding vector is obtained by maximizing the matching weighted SLNR. Simulation results show the superiority of the proposed scheme in terms of bit error rate over the conventional SLNR schemes.

Real-time on-chip measurement of bit error rate (BER) for high-speed analog-to-digital converters (ADCs) does not only require expensive multi-port high-speed data acquisition equipment but also enormous post-processing. This paper proposes a low-cost built-in-self-test (BIST) circuit for high-speed ADC BER test. Conventionally, the calculation of BER requires a high-speed adder. The presented method takes the advantages of Gray coding and only needs simple logic circuits for BER evaluation. The prototype of the BIST circuit is fabricated along with a 5-bit high-speed flash ADC in a 90-nm CMOS process. The active area is only 90 µm 70 µm and the average power consumption is around 0.3 mW at 700 MS/s. The measurement of the BIST circuit shows consistent results with the measurement by external data acquisition equipment.

This paper aims at channel modeling and bit error rate (BER) performance improvement with diversity reception for in-body to on-body ultra wideband (UWB) communication for capsule endoscope application. The channel characteristics are firstly extracted from 3.4 to 4.8 GHz by using finite difference time domain (FDTD) simulations incorporated with an anatomical human body model, and then a two-path impulse response channel model is proposed. Based on the two-path channel model, a spatial diversity reception technique is applied to improve the communication performance. Since the received signal power at each receiver location follows a lognormal distribution after summing the two path components, we investigate two methods to approximate the lognormal sum distribution in the combined diversity channel. As a result, the method matching a short Gauss-Hermite approximation of the moment generating function (MGF) of the lognormal sum with that of a lognormal distribution exhibits high accuracy and flexibility. With the derived probability density function (PDF) for the combined diversity signals, the average BER performances for impulse-radio (IR) UWB with non-coherent detection are investigated to clarify the diversity effect by both theoretical analysis and computer simulation. The results realize an improvement around 10 dB on Eb/No at BER of 10-3 for two-branch diversity reception.

This paper presents measurement results of bit error rate (BER) and soft error rate (SER) improvement on 150-nm FD-SOI 7T/14T (7-transistor/ 14-transistor) SRAM test chips. The reliability of the 7T/14T SRAM can be dynamically changed by a control signal depending on an operating condition and application. The 14T dependable mode allocates one bit in a 14T cell and improves the BER in a read operation and SER in a retention state, simultaneously. We investigate its error rate mitigating mechanisms using Synopsys TCAD simulator. In our measurements, the minimum operating voltage was improved by 100 mV, the alpha-induced SER was suppressed by 80.0%, and the neutron-induced SER was decreased by 34.4% in the 14T dependable mode over the 7T normal mode.

The impact of non-ideal delay line (DL) along with group delay ripple (GDR) on the performance of ultra wide bandwidth (UWB) system has not yet been studied in previous literatures. In this paper, according to the currently designed DLs, we propose a statistical GDR model to achieve a practical UWB DL, and investigate the degradation in average bit error rate (BER) caused by the GDR for the transmitted-reference (TR) UWB communication systems. According to the analysis results, an improved autocorrelation receiver (AcR) is proposed. Through Monte Carlo simulations, the great performance improvement of the proposed AcR is verified by comparing it with the conventional TR AcR under non-ideal DL conditions. The proposed receiver framework is simple enough to enable a tractable analysis, and provides valuable insights for designing a practical TR UWB AcR that experiences GDR.

The extended binary phase shift keying (EBPSK) transmission system with ultra narrow bandwidth has excellent BER performance, which raises many doubts with the researchers. Therefore, on the premise of the existence of a special filter that can transform the modulated phase information into amplitude information, the theoretical BER formula of EBPSK system in Additive White Gaussian Noise (AWGN) channel has been deduced. This paper gives the theoretical values of the parameters in the above BER formula and discusses the effects of parameters on BER firstly. Then the paper shows that the special impacting filter satisfies the above assumption, therefore, in the frame of binary detection theory, the excellent performance of high-efficiency EBPSK system can be explained and the correction of the theoretical BER formula can be validated.

The objective of this study is to investigate the feasibility of an ultra wideband (UWB) impulse radio system for in-body to off-body wireless communication for biomedical applications. At first, a UWB antenna is designed in the UWB low band for implant use in the chest. Then the channel model is extracted and established based on the finite difference time domain (FDTD) simulation with an anatomical human body model. The established channel model consists of a small set of parameters for generating discrete time impulse responses. The generated model shows good agreement with the FDTD-calculated result in terms of key communication metrics. For effective communication over the multipath-affected channel, the pulse position modulation is employed and a 2-finger RAKE structure with a constant temporal delay is proposed in the receiver. The bit error rate performance has shown the validity of the system in the in-body to off-body chest channel.

In this paper, the optimum combination of optical pseudo-noise (PN) code and modulation scheme to achieve high total data transmission rate is presented. Moreover, the bit error rate (BER) performance of a wireless OCDMA system using chip-level detection is evaluated through theoretical analysis in the multi-user case. It is shown that, in a wireless OCDMA system with chip-level detection, the total data transmission rate of a multi-pulse pulse position modulation (MPPM) systems with optical pseudo-noise code generated by an M-sequence is better than that of an MPPM system with optical orthogonal code and that of an MPPM system with an extended prime code sequence. Moreover, the total data transmission rate of an MPPM/SIK system using modified pseudo orthogonal M-sequence sets can achieve more than 1.0 [bit/chip].

In this paper, newly-found properties of the pseudo-ternary maximum-length shift register sequences (pseudo-ternary M-sequences) are described. In particular, the balance properties, the run-length distribution, the cross-correlation properties, and the decimation relationships are shown. The pseudo-ternary M-sequence is obtained by subtracting the one-chip shifted version from the {+1,-1}-valued M-sequence. Moreover, in this paper, performances of the direct sequence spread spectrum (DS/SS) system using the pseudo-ternary M-sequence are analyzed. In the performance evaluation, tracking error performance (jitter) and bit error rate (BER) performance that takes the jitter into account in DS/SS system with a pseudo-ternary M-sequence non-coherent DLL are evaluated. Using the pseudo-ternary M-sequence instead of the conventional M-sequences can improve the tracking error performance about 2.8 [dB]. Moreover, BER of the DS/SS system using the pseudo-ternary M-sequence is superior about 0.8 [dB] to that using the {+1,-1}-valued M-sequence.

Generalized selection combining (GSC) was recently proposed as a low-complexity diversity combining technique for diversity-rich environments. This letter proposes a multi-hop Decode-and-Forward Relaying (MDFR) scheme in conjunction with GSC and describes its performance in terms of average bit error probability. We have shown that the proposed protocol offers a remarkable diversity advantage over direct transmission as well as the conventional decode-and-forward relaying (CDFR) scheme. Simulation results are also given to verify the analytical results.

Ultra wideband (UWB) on-body communication is attracting much attention in biomedical applications. In this paper, the performance of UWB on-body communication is investigated based on a statistically extracted on-body channel model, which provides detailed characteristics of the multi-path-affected channel with an emphasis on various body postures or body movement. The possible data rate, the possible communication distance, as well as the bit error rate (BER) performance are clarified via computer simulation. It is found that the conventional correlation receiver is incompetent in the multi-path-affected on-body channel, while the RAKE receiver outperforms the conventional correlation receiver at a cost of structure complexity. Different RAKE receiver structures are compared to show the improvement of the BER performance.

A 4+12+16 amplitude phase shift keying (APSK) modulation outperforms other 32-APSK modulations such as rectangular or cross 32-quadrature amplitude modulations (QAMs) which have a high peak to average power ratio that causes non-negligible AM/AM and AM/PM distortions when the signal is amplified by a high-power amplifier (HPA). This modulation scheme has therefore been recommended as a standard in the digital video broadcasting-satellite2 (DVB-S2) system. In this letter, we present a new bits-to-symbol mapping with a better bit error rate (BER) for a 4+12+16 APSK signal in a nonlinear satellite channel.

A coordinate plane representation of the resource requirements of digital modulation methods is presented, and an overall resource efficiency measure is proposed. This measure can be used for the comparison of digital modulation methods and the evaluation of an emerging modulation technique. Several typical digital modulation methods are compared based on this measure to show its validity.

In this letter, a simple product code is proposed for constant-amplitude biorthogonal multicode (CABM) modulation. In CABM modulation, vertical redundant bits are used for constant amplitude coding. The proposed product code can be constructed by using additional horizontal redundant bits. The hardware complexity of the encoder and decoder pair is very low. Simulation results show that the bit error rate performance of the system with the proposed coding scheme is improved as compared with conventional CABM demodulation.

This letter proposes a novel scheme of joint antenna combination and symbol detection in multi-input multi-output (MIMO) systems, which simultaneously determines the antenna combination coefficients to lower the RF chains and designs the minimum bit error rate (MBER) detector to mitigate the interference. The joint decision statistic, however, is highly nonlinear and the particle swarm optimization (PSO) algorithm is employed to reduce the computational overhead. Simulations show that the new approach yields satisfactory performance with reduced computational overhead compared with pervious works.

Combining relaying and multi-input multi-output (MIMO) transmission is a generic way to overcome the channel-fading impairments. Best antenna selection is a simple but efficient MIMO method that achieves the full diversity and also serves as a lower bound reference of MIMO performance. For a dual-hop MIMO system with an ideal amplify-and-forward (AF) relaying gain and best antenna selection, we provide a probability density function (PDF) of received signal-to-noise ratio (SNR) and an analytic BER equation when using M-ary PSK in Rayleigh fading channels. The analytic result is shown to exactly match with simulated one. Furthermore, the effect of link unbalance between the first hop and the second hop, due to differences in the number of antennas deployed in both hops as well as in the average power of channel coefficients, on the BER performance is numerically investigated and the results show that the links with better balance give better performance.

We report on suppressing adjacent-frequency interference (AFI) by using a RF receive bandpass-filter (BPF) with high-selectivity. By considering a high temperature superconducting (HTS) multi-pole BPF as a high selective BPF, the effect was estimated by numerical simulations. The simulations of the RF signals with an OFDM modulation transmitted to the demodulator via the BPF were carried out using the HTS BPF for 5 GHz band. The results confirmed the improvement of the bit error rate (BER) characteristic with the assumed HTS BPF with the high multi-poles under a strong AFI.

In this letter, we introduce a new adaptive beamforming assisted receiver based on minimizing the approximate negentropy (NEGMIN) of the estimation error. We consider the approximate negentropy by using a nonpolynomial expansion of the estimation error as a new performance criterion to improve the performance of adaptive beamforming receivers based on the minimizing minimum mean squared error (MMSE) criteria. Negentropy includes higher order statistical information and its minimization provides improved converge, performance, and accuracy compared to traditional methods such as MMSE in terms of bit error rate (BER).