Software defined radio employing low density spreading for Canadian military applications

无线技术是军事作战场景中不可或缺的一部分。士兵和基地之间的通信对于加拿大军事人员在敌对环境中执行任务时的安全和成功至关重要。军事人员使用的无线电设备必须轻便、机动，所使用的波形必须具有抗干扰、抗截获和抗探测能力。扩频通信最初的构想是由于其抗干扰性(AJ)、低截获概率(LPI)和低检测概率(LPD)能力。然而，直接序列扩频(DS-SS)使用对极扩频码，此后已被证明只需对接收信号平方即可检测到，允许敌人通过对平方信号进行三角测量来定位发射机，并且也容易受到脉冲干扰。低密度扩展(LDS)目前是第五代(5G)无线通信系统的候选方案，它使用扩展码，其中扩展码片由零和不同的复数表示。零的数量超过了非零值，这导致了低密度信号。当此信号平方时，结果仍然是低密度高带宽信号，很难检测到，因此进行三角测量。并且这种类型的信号与脉冲干扰相抗衡，因为通常当干扰器发射干扰突发时，发射的信号为0。这意味着在这些情况下，干扰信号将被接收器的相关器抵消。*目前的军用无线电采用慢跳频扩频(FH-SS)技术，这种技术很容易被跟随器干扰机检测到并进行干扰。这些无线电是以硬件为基础的，已经运行了多年。我们建议使用软件定义的无线电平台来实现用于军事无线通信的LDS无线电，这将允许快速采用新出现的无线电技术。我们将在多种不同的电子战(EW)场景下，使用MatLab中的蒙特卡罗模拟以及NordiaSoft的软件定义无线电工具包的模拟来测试LDS解决方案，例如干扰和敌方定位。然后，我们将比较我们的解决方案与现有的三级无线电的性能。我们还将考虑用于高负载通信场景的LDS，并考虑使用多用户检测技术来确定这些无线电用于商业用途的频谱效率。****

Wireless technology is an integral part of military combat scenarios. Communications between soldiers and base are essential to the safety and success of Canadian military personnel while performing their duties in hostile environments. The radio equipment used by military personnel must be lightweight and mobile, and the waveforms used must be resistant to jamming, interception and detection. Spread spectrum communications was originally conceived due to its antijam (AJ), low probability of intercept (LPI) and low probability of detection (LPD) capabilities. However, direct sequence spread spectrum (DS-SS), which uses antipodal spreading codes, has since been shown to be detectable simply by squaring the received signal, allowing the enemy to locate the transmitter by triangulating the squared signal and is also susceptible to pulsed jamming. Low density spreading (LDS), which is currently a candidate for 5th generation (5G) wireless communication systems, uses spreading codes where the spreading chips are represented by zeroes and different complex numbers. The zeroes outnumber the nonzero values, which leads to a low density signal. When this signal is squared, the result is still a low density high bandwidth signal, which is difficult to detect and therefore triangulate. And this type of signal combats pulsed jamming because often when the jammer transmits a jamming burst, the transmitted signal is 0. This means the jamming signal will get cancelled out by the correlator at the receiver during these instances. ****Current military radios employ slow frequency hopped spread spectrum (FH-SS) techniques which are easily detected and then jammed by follower jammers. These radios are hardware-based and have been in operation for many years. We propose to implement LDS radio for military wireless communications employing a software defined radio platform, which will allow for quick adoption of newly emerging radio techniques. We will test the LDS solution, using Monte Carlo simulations in Matlab as well as emulations using NordiaSoft's Software Defined Radio Kits, under a number of different electronic warfare (EW) scenarios, such as jamming and hostile localization. We will then compare the performance of our solution to existing miltiary radios. We will also consider LDS for heavily loaded communication scenarios and consider multiuser detection techniques to determine spectral efficiency of these radios for commercial use. ****