一种用于分组数据可靠传输的Ⅱ型混合ARQ方法

本文基于码率匹配截短Turbo码和“码字校验交替重传”方案，提出了一种新的Ⅱ型混合ARQ方法，并将其应用于移动通信系统的分组数据业务中。仿真结果和分析表明，综合系统性能和复杂性两方面考虑，该方法不失为一种实现分组数据可靠传输的最佳解决方案。     

Fin-line Pin diode BPSK and QPSK modulators

A low insertion lose fin-line PIN diode phase shifter is presented. 90° and 180° phase shifters are realized respectively. Phase error less than 5° and bandwidth 3 GHz at Ka band are achieved. The insertion loss is better than 0.5dB. The BPSK and QPSK modulators consisting of this phase shifter and fin-line coupler are also given. The circuits and results are given.     

一种改进的BPSK/QPSK信号调制识别算法

提出了一种基于顺序统计量特征的二进制相移键控/正交相移键控(BPSK/QPSK)信号调制识别算法.对观测信号进行平方并做离散傅里叶变换运算,将变换结果取模后去除最大值得到修正频谱,并取修正频谱的最大值作为识别特征量,利用恒虚警准则确定判决门限,将识别特征量与门限比较来完成对BPSK和QPSK两种调制信号的识别.计算机仿真表明,当信噪比适度时,所提算法可对BPSK及QPSK两类信号进行有效识别.当信噪比大于1 dB时,算法的平均识别正确率达到90%以上.     

一种有效的BPSK/QPSK信号调制识别方法

根据不同调制信号相位差分的变化规律,文章提出了基于相位差分峰值幅度比较的BP SK/QPSK调制识别方法。仿真结果验证了调制识别方法的有效性。     

Punctured turbo-codes for BPSK/QPSK channels

We discuss a procedure for designing high-rate turbo-codes via puncturing, with applications to BPSK/QPSK channels. Rates in the form k/(k+1), 2⩽k⩽16, are considered for constituent encoders with memory sizes m=3 and 4. The algorithm includes the selection of constituent encoder generator polynomials, puncture patterns, and interleavers with the goal of maximizing the minimum codeword weight for weight-two and weight-three inputs. The performance of the proposed codes are found via computer simulation and are observed in each case to be less than 0.9 dB (m=3), and 0.75 dB (m=4), from their respective channel capacity limits at a bit-error rate of 10^-5. We consider two applications of punctured turbo-codes     

Integrated Balanced BPSK and QPSK Modulators for the Ka-Band

Microwave integrated circuit (MIC) balanced biphase-shift-keying (BPSK) and quadri-phase-shift-keying (QPSK) modulators have been achieved in the 27-GHz band. The modulators are fabricated using a combination of microstrip lines and slot lines, viz., tow-sided MIC. The diodes used are beam-lean Schottky-barrier diodes. Balanced BPSK modulation is performed by path-switching and mode transformation from the slot line to microstrip lines. The insertion loss is 2.2 dB at a carrier frequency of 27 GHz. The phase error and the amplitude deviation are less than 1° and 0.5 dB, respectively. The QPSK modulator consists of two BPSK modulators, a power divider, and a branch-line hybrid coupler. The configuration of the modulator is the parallel-connected type. The insertion loss is 6.3 dB at a carrier frequency of 27 GHz. The phase error is less than 2°, and the rise time and fall time of the modulated earner are less than 300 ps. The isolation between the carrier input port and the QPSK modulated earner output port is greater than 25 dB. These modulators can be extended to the millimeter-wave band.     

Intersymbol interference effects on BPSK and QPSK carrier trackingloops

The tracking performance of three conventional carrier tracking loops in the presence of intersymbol interference (ISI) is analyzed. The closed-form expressions for the squaring losses of BPSK (binary phase-shift-keyed) low-SNR (signal-to-noise ratio), BPSK high-SNR, and QPSK (quaternary phase-shift-keyed) low-SNR loops are derived. ISI is shown to affect the BPSK high-SNR loop as much as the I-Q loop despite the nonlinear effect of the hard-limiter. For the QPSK carrier tracking loop, the degradation is shown to be greater due to the modulation of both components of the carrier. In this case, ISI, in addition to modifying the coefficients in the squaring loss, adds a new term not present in wideband channels. In all cases, a unity squaring loss could not be achieved because of the irreducible error due to pattern noise. This noise is only present in band-limited channels and is dependent on the data model used     

瑞利衰落信道下MPSK信号调制方式识别

调制识别是非协作通信系统接收机设计中的重要研究课题。在实际环境中,噪声和信道衰落是影响信号调制方式识别的重要因素。针对瑞利衰落信道上MPSK较难识别的情况,提了基于似然比的识别算法,并根据最大似然准则对瑞利信道的参数进行了估计完成对2种调制信号的识别。仿真结果表明:在存在高斯白噪声的瑞利衰落信道的环境下,以BPSK和QPSK为例,正确识别率达到90%。     

BPSK/QPSK调制方式下的STC-OFDM系统性能

对STC-OFDM系统模型进行了详细介绍,分析了系统在BPSK和QPSK调制方式下的误码率性能,并与OFDM系统进行比较。仿真结果表明,将空时编码技术和OFDM系统结合在一起,可以进一步提高系统性能。此外,对于OFDM系统,BPSK和QPSK调制的误码率性能是一样的,但在STC-OFDM系统中,BPSK调制的误码率性能明显优于QPSK。     

BER performance of BPSK transmissions over multipath channels

A new closed form expression for the bit error rate (BER) performance of binary phase shift keying (BPSK) transmissions over frequency selective channels is presented. The expression is obtained through a novel approximation of the Gaussian Q(middot) function by a fixed series of sinusoids with exponentially decreasing amplitudes. Numerical results demonstrate the accuracy of the derived expression     

An effective go-back-N ARQ scheme for variable-error-rate channels

In nonstationary channels, error rates vary considerably. The author proposes an effective go-back-N ARQ scheme which estimates the channel state in a simple manner, and adaptively switches its operation mode in a channel where error rates vary slowly. It provides higher throughput than other comparable ARQ schemes under a wide variety of error rate conditions     

Classification of BPSK and QPSK Signals Using an Antenna Array

We propose in this paper the use of a uniform linear array to improve the classification accuracy of two phase-shift keying (PSK) signals at different multiplicities, in particular, binary PSK (BPSK) and quadrature PSK (QPSK) signals. The proposed modulation classifier is based on the likelihood ratio test, where an additive white Gaussian noise with direct line-of-sight transmission is assumed. The likelihood functions of the two PSK signals depend on an unknown phase shift due to the signal arrival angle and the spatial separation of the antenna elements. A computationally efficient two-step processing is proposed to estimate the phase shifts to be used in the likelihood ratio test. The proposed phase shift estimation method reduces the computation significantly compared to the maximum likelihood solution, which requires numerical exhaustive search, and has an estimation accuracy reaching the Cram\'er-Rao lower bound at moderate signal-to-noise ratios. The proposed classifier improves the performance considerably compared to a single element receiver. Furthermore, the proposed classifier demodulates the transmitted symbol sequence in conjunction with the classification process, and no separate demodulation for the data symbol is needed after classification. Simulation results for BPSK and QPSK classification are provided.     

A self-normalizing symbol synchronization lock detector for QPSK and BPSK

This paper presents a new lock detector structure for symbol timing recovery PLLs (Phase Lock Loops), which operate in QPSK. (Quaternary Phase Shift Keying) and BPSK (Binary Phase Shift Keying) receivers in AWGN (Additive White Gaussian Noise) channels. The lock detector requires only 2 samples/symbol, which coincide with those required for the Gardner timing error detector. Simulation results are used to characterize the detector's behavior quantitatively. Both rectangular and square-root raised-cosine baseband data pulses are treated. It emerges that the lock detector has two very useful qualities. First, it is self-normalizing, and, secondly, the channel E/sub S//N/sub 0/ ratio can be easily determined from its value when the receiver is locked. Finally, a simple hardware structure is found for the lock metric computation process, which allows for its efficient implementation within an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).     

A BPSK/QPSK Timing-Error Detector for Sampled Receivers

A simple algorithm for detection of timing error of a synchronous, band-limited, BPSK or QPSK data stream is proposed. The algorithm requires only two samples per symbol for its operation. One of the two samples is also used for the symbol decision. Derivation of thescurve reveals a sinusoidal shape.     

BPSK、QPSK、OQPSK、UQPSK信号识别研究

采用提取信号相位并用直方图统计的方法对BPSK、QPSK、OQPSK、UQPSK信号进行识别,并分析不同噪声背景下对这四种信号识别的影响。仿真结果表明在满足一定信噪比的条件下,能够完成对这四种调相信号的识别。     

基于瞬时测频的BPSK和QPSK信号参数估计

针对RWR/ESM中瞬时测频(IFM)无法对相位编码信号脉内参数进行测量的问题,提出了一种对载频的估计方法和两种对码元的估计方法。通过采用高采样率ADC采样、解模糊、平滑和取均值的处理流程对信号载频进行估计;利用相位跳变和相干解调两种方法分别对码元进行估计。仿真结果证明了上述方法对载频和码元估计的有效性。在对码元的估计中:相位跳变法实时性好,但需要一定的先验知识;相干解调法不需要任何先验知识,但实时性不好。所得结论对工程应用研究具有一定参考价值。     

Cramer-Rao bounds of SNR estimates for BPSK and QPSK modulatedsignals

We derive Cramer-Rao lower bounds (CRLBs) for the estimation of signal-to-noise ratio (SNR) of binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK) modulated signals. The received signal is corrupted by additive white Gaussian noise (AWGN). The lower bounds are derived for non-data-aided estimation where the transmitted symbols are unknown at the receiver. The bounds are compared to those for data-aided estimations (known symbols at the receiver). It is shown that at low SNR there is a significant difference between the bounds for non-data-aided and data-aided estimations     

Adaptive type II hybrid ARQ scheme using zigzag code

The authors propose a new hybrid type II ARQ scheme based on the simple multidimensional concatenated zigzag code. Owing to the fact that the error-correcting capability of zigzag codes is far better than that of conventional convolutional codes, the throughput of our scheme is better than existing hybrid ARQ schemes     

Generalized type II hybrid ARQ scheme using punctured convolutionalcoding

A method is presented to construct rate-compatible convolutional (RCC) codes from known high-rate punctured convolutional codes, obtained from best-rate 1/2 codes. The construction method is rather simple and straightforward, and still yields good codes. Moreover, low-rate codes can be obtained without any limit on the lowest achievable code rate. Based on the RCC codes, a generalized type-II hybrid ARQ scheme, which combines the benefits of the modified type-II hybrid ARQ strategy of J. Hagenauer (1988) with the code-combining ARQ strategy of D. Chase (1985), is proposed and analyzed. With the proposed generalized type-II hybrid ARQ strategy, the throughput increases as the starting coding rage increases, and as the channel degrades, it tends to merge with the throughput of rate 1/2 type-II hybrid ARQ schemes with code combining, thus allowing the system to be flexible and adaptive to channel conditions, even under wide noise variations and severe degradations