Rank‐based dynamic frequency hopping without strict coordination in IEEE 802.22 WRAN system

In IEEE 802.22 wireless regional area networks (WRAN), it is indispensable to prevent the in‐use channel from interfering with incumbent services such as digital TV. To achieve this end, in this paper, we propose a dynamic frequency hopping based on rank accounting. In this method, a base station utilizes a ranking database where a rank of a channel which is used frequently is high. Each base station uses an idle channel whose rank is the highest based on the database, and hence this can reduce the number of channels which are used for the data transmission. Moreover, the proposed method performs interference avoidance processes. The proposed method does not require a strict coordination for base stations. We evaluate the performance of the proposed method with simulation. Numerical examples show that the failure probability of the channel switching for the proposed method is smaller than that for the conventional random method. It is also shown that the number of channels that are used for the data transmission can be reduced by using the proposed method. Finally, we investigate the performance of the proposed method in some situations. Copyright © 2011 John Wiley & Sons, Ltd.     

Parallel and Gaussian frequency hopping for dynamic coexistence in the unlicensed band

With the surge of short‐range wireless applications, more networks are being deployed in the unlicensed radio band. The challenge that emerges is to accommodate these networks without breaching current rules and regulations on frequency usage. This paper studies the coexistence of several independent and dynamic wireless networks using the frequency hopping technique. We propose a novel hopping scheme that minimizes mutual interference and allows more networks to collocate effectively, but does not violate restrictions imposed by the Federal Communications Commission (FCC) regarding frequency constraint (related to the minimum number of frequencies in a hopping set) and time constraint (related to the maximum duration of using a particular frequency). The coexisting networks follow the Gaussian distribution in choosing transmission frequencies from parallel hopping spaces without the overhead of extra message exchange among networks. Simulation results on key metrics such as channel collision rate, goodput, and fairness in channel usage are presented to establish the viability of the proposed scheme in comparison with other contemporary approaches. Copyright © 2011 John Wiley & Sons, Ltd.     

数据驱动的开放动态频谱接入系统构建方法

在认知无线电(CR)背景下,动态频谱接入已成为提高无线网络频谱利用率的重要途径。基于全球移动通信系统-铁路(GSM-R)系统中采集的细粒度频谱监测数据,提出一种数据驱动的深度学习方法,建模频谱模式,并建立一套动态频谱接入访问框架。采用一种深度频谱生成模型指导频谱分配;设计一种综合递归序列表征与场景特征嵌入的深度网络,建模和预测短时频谱占用情况,并由此提出一种动态信道接入策略。进一步,利用软件无线电(SDR)平台实现一套跳频系统,并将其与动态频谱接入策略进行集成。使用真实的历史频谱数据评估该系统的数据吞吐能力,测试结果表明,所提方法及构建的跳频系统能有效提高机会通信能力,高效利用频谱资源。该频谱接入框架及SDR系统实现具有较强的通用性,易于集成到不同场景和频段的系统中。     

一种基于频率特征及动态窗长的钢琴调音算法

时域分析法是一种基本的语音分析方法。由于钢琴乐音模型与语音模型相似,故语音时域分析法可被用于钢琴乐音分析中。提出一种基于频率特征及动态窗长的钢琴基音识别时域算法,该算法能根据检测目标设计更为合适的分帧加窗模式,经过实验,可有效地提高检测精度及速度,在钢琴调音及单乐音基音识别应用中具有推广意义。     

正交信号MIMO雷达动态范围与弱目标检测性能分析

正交信号MIMO雷达各阵元发射相互正交的信号波形,多个信号波形在空间不能叠加形成高增益的窄波束,经目标反射回来的回波信号的动态范围较传统相控阵雷达有所降低,这将有利于改善对强杂波中的弱目标信号的检测性能。动态范围往往取决于杂波功率,本文分析了基于OFDM-LFM信号的MIMO雷达的信号功率问题,并提出利用优化的随机相位来降低信号瞬时功率,从而改善回波信号的动态范围。仿真比较了在接收机动态范围一定的条件下,MIMO雷达相对于传统相控阵雷达在弱目标检测性能方面的改善。