Chaotic frequency hopping sequences

This letter describes a novel family of frequency hopping sequences generated by chaotic systems. The sequences give a uniform spread over the entire frequency bandwidth. In addition to having good Hamming correlation properties, they possess ideal linear span. The sequences produce almost as good performance as random hopping patterns when used in frequency hopping code-division multiple-access (FH/CDMA) systems. Many numerical examples based on a digital chaos generator are presented     

Maximal length sequences for frequency hopping

Normally, frequency hopping sequences for spread-spectrum communication systems are obtained by selecting groups of elements of binary m sequences. An alternative to using groups of binary m-sequence elements is developed. It involves obtaining nonbinary m sequences with the number of desired hopping frequencies equal to the number of symbols in the finite field which the nonbinary m sequence is over. The grouping of elements of binary m sequences does not necessarily have the m sequences. In addition, the autocorrelation function of the nonbinary m sequence has a maximal period, whereas the frequency hopping sequences obtained from the grouping of elements of binary m sequences may not have a maximal period     

慢跳频的伪随机序列

本文基于ＧＦ（２）域上的增广质数序列,提出了一类ＧＦ（Ｐ＾Ｋ）域上的增广质数跳频序列,对其差的游程特性进行了改进,并根据慢跳频系统的要求进行了宽间隔处理。计算机模拟分析表明：宽间隔增广质数跳频序列具有良好的汉明相关特性,是一类优良的跳频序列,适合于慢跳频系统。     

Maximum based detection of slow frequency hopping signals

This letter studies a maximum based channelized intercept receiver. A comparison is made with the traditional logical OR based channelized intercept receiver. Theoretical and simulated results are presented using some parameters of a typical slow frequency-hopping combat radio (SINCGARS). Numerical results show that assuming the receiver bandwidth is not limited the maximum based receiver performs better than the traditional logical OR based receiver does.     

组合跳变随机平移宽间隔混沌跳频序列设计

为进一步提高宽间隔跳频序列的性能,基于混沌跳频序列,针对随机平移替代法存在的“窄点”平移与序列平衡性的矛盾问题,提出了一种新的组合跳变随机平移法。该方法在随机平移替代法的基础上取消“窄点”修正,引入组合跳变序列控制频点宽间隔映射。为兼顾组合跳变随机平移法产生序列的平衡性、汉明自相关性和宽间隔特性,构造了跳频序列的复合目标优化函数,引入粒子群算法计算得到最优的序列控制参数。仿真结果表明,组合跳变随机平移法可构造更多的序列,且产生的宽间隔混沌跳频序列具有更好的平衡性、汉明相关性和复杂度,采用粒子群优化获取的控制参数可以实现序列性能的均衡最优。     

蓝牙自适应跳频序列的性能分析

蓝牙自适应跳频序列性能优越,有着广泛的应用前景.通过仿真计算,分析了蓝牙自适应跳频序列的频率均匀性、汉明相关特性、跳频间隔分布特性、序列的线性复杂度、组网特性和系统容量.     

Optimal frequency hopping sequences: a combinatorial approach

Frequency hopping multiple access (FHMA) spread-spectrum communication systems employing multiple frequency-shift keying (MFSK) as data modulation technique are investigated from a combinatorial approach. A correspondence between optimal frequency hopping (FH) sequences and partition-type difference packings is first established. By virtue of this correspondence, FHMA systems with a single optimal FH sequence each are constructed from various combinatorial structures such as affine geometries, cyclic designs, and difference families. Combinatorial recursive constructions are also presented. Many new infinite series of optimal FH sequences are thus obtained. These new FH sequences are also useful in ultra wideband (UWB) communication systems.     

跳频序列设计理论的研究进展

跳频技术具有抗干扰和多址组网性能，在军事无线电通信、民用移动通信、现代雷达和声纳等电子系统中具有重要的应用。跳频序列用于控制载波频率随机时间的变化规律，其性能对跳频系统的性能有重大影响。本文综述跳频序列设计理论的研究成果，并指出今后的发展方向。     

仿蓝牙序列的一类新的跳频序列

由于蓝牙跳频序列性能优越,因此在军事通信抗干扰系统中有广阔的应用前景。通过改造蓝牙序列的 生成算法,得到了一类新的跳频序列。新序列除具有蓝牙序列的一般特性外,与蓝牙序列相比,其周期更长、密钥 量更大、汉明互相关性能更好。同时给出了在应用中应注意的一些问题。     

Reliable adaptive modulation and interference mitigation for mobile radio slow frequency hopping channels

The long range fading prediction algorithm for Slow Frequency Hopping (SFH) systems is proposed and demonstrated to enable combined adaptive modulation and adaptive frequency diversity to mitigate the effects of fading and partial-band interference. Significant performance gains are demonstrated relative to non-adaptive methods in realistic mobile radio SFH channels where the total bandwidth does not exceed approximately 15 times the coherence bandwidth.     

High level trellis-coded modulation with slow frequency hopping forland mobile communications

The use of high level modulation systems such as trellis-coded 8-PSK and trellis-coded 16-QAM, with slow frequency hopping, pilot symbol aided and small-sized interleaving techniques is proposed for land mobile communications. The bit error rate (BER) performance of those systems in the presence of additive white Gaussian noise (AWGN), cochannel interference (CCI), and slow Rayleigh fading are evaluated by computer simulation. Space diversity is applied to enhance the system performance. The authors show that by choosing optimum interleaving size and number of frequency hopped (FH) channels, the proposed systems give considerable performance improvement and much less delay, especially in a slow fading environment     

短波慢跳频系统误码率分析

本文分析了在慢跳频系统中由于多径效应引起的误码率，并推导了经过自适应均衡后的误码率。模拟分析结果表明：基于平方根卡尔曼算法的判决反馈均衡器的引入大大降低了误码率。     

Hit probability between frequency hopping sequences generated byReed-Solomon and Hermitian codes

Frequency hopping systems produced by either Reed-Solomon (RS) or Hermitian codes (AG) are compared. The results show that AG codes perform better than RS codes if the ratio of the number of hits by length of sequences is considered     

Indoor radio communications using time-division multiple accesswith cyclical slow frequency hopping and coding

The authors describe and analyze a flexible, robust, multichannel time-division-multiple-access (TDMA) radio communications system that is ideally suited for portable as well as mobile indoor use. It uses noncoherent signaling and incorporates slow cyclical frequency hopping and burst-error-correcting coding to provide low-error communications at aggregate rates of several megabits per second without the need for antenna diversity or adaptive equalization. The system can be implemented in a small building using a centralized architecture or in a large building using a distributed antenna system. The TDMA protocol allows the various users the flexibility of choosing their own desired rates of data communications. Moreover, the capability of using different levels of coding gives the users the option of selecting their own error performance. The ability to combat interference is one of the salient features of this system     

Optimum processing gain for a hybrid direct sequence/slow frequency hopping code division multiple access cellular system over Rayleigh fading channels: the direct sequence/slow frequency hopping code division multiple access case

In this paper, the optimum value of the processing gain of a hybrid direct sequence/slow frequency hopping code division multiple access cellular system, when operating in a Rayleigh fading environment, is examined. The optimization is based on the maximization of the average spectral efficiency achieved, expressed in bits per second per Hertz, which is estimated in terms of the achievable average channel capacity (in the Shannon–Hartley theorem sense) per user during the operation over a broadcast cellular time‐varying link. The analysis leads to a simple theoretical novel closed‐form expression for the optimal processing gain that is related with the system's parameters but becomes independent of hopping frequencies assigned to each system's cell. Finally, the expression derived can be useful for the practical design of a direct sequence/slow frequency hopping code division multiple access cellular system and for an initial quantitative analysis. Numerical results are presented to illustrate the presented analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

Hybrid slow frequency hopping/ direct sequence spread spectrum indoor communication systems with QPSK modulation

This paper analyses the performance of a spread-spectrum multiple access system based on hybrid direct sequence/slow frequency hopping techniques with QPSK modulation. The performance is analyzed considering multipath and multiple access interferences and an indoor channel having Rician distributed path gains. The system performance is investigated for 2 diversity techniques and compared, for given delay spread, bandwidth and bit rate, with the performance provided by bpsk modulation. It is shown that the larger symbol duration of QPSK is favorable to combat the effect of multipath propagation.     

差分跳频技术

差分跳频技术是近年出现的一种新型扩频通信技术,它集跳频图案、信息调制与解调等功能于一体,构成与传统跳频技术完全不同的技术体制。对近年出现的扩频通信新技术-差分跳频技术进行全面介绍。在对差分跳频关键技术进行详细分析的基础上,着重说明其优点及尚需解决的问题。     

GHz band frequency hopping PLL-based frequency synthesizers

In this paper we describe a full-integrated circuit containing all building blocks of a completed PLL-based synthesizer except for low pass filter（LPF）. The frequency synthesizer is designed for a frequency hopping （FH） transceiver operating up to 1.5 GHz as a local oscillator. The architecture of Voltage Controlled Oscillator （VCO） is optimized to get better performance, and a phase noise of -111.85-dBc/Hz @ 1 MHz and a tuning range of 250 MHz are gained at a centre frequency of 1.35 GHz. A novel Dual-Modulus Prescaler（DMP） is designed to achieve a very low jitter and a lower power. The settling time of PLL is 80 μs while the reference frequency is 400 KHz. This monolithic frequency synthesizer is to integrate all main building blocks of PLL except for the low pass filter, with a maximum VCO output frequency of 1.5 GHz, and is fabricated with a 0.18 μm mixed signal CMOS process. Low power dissipation, low phase noise, large tuning range and fast settling time are gained in this design.     

Analysis of the fast acquisition method in frequency hopping systems

Versions of implementing initial synchronization in systems with pseudorandom operating frequency tuning are studied. These versions are based on applying a recurrent acquisition with an autoregressive spectral estimation. Known algorithms are analyzed, and versions of their modification are proposed. Simulation models of considered solutions are constructed, and quantitative data that characterize their noise immunity are obtained.