超宽带（UWB）

超宽带（UWB）是最广泛使用的高分辨率和短程定位的无线标准，以及与数据通信一起进行测距。UWB是一个脉冲无线电技术，具有500 MHz的最小带宽，在子GHz和3.1-10.6 GHz范围内操作。

UWB.also has a maximum power spectral density of -41.3 dBm/MHz across all frequencies, which is much less than WiFi, Bluetooth^®，Zigbee.^®和GPS并避免干扰这些无线信号以支持短程通信。金宝app超宽带使用短脉冲（<2 ns）进行传输，使其免于多径衰落并支持位置和测距应用程序。金宝app

UWB支持的其他应用程序是：金宝app

• Secure access control
• 安全无线支付
• 无线健康传感器
• Device-to-device communication

Some UWB characteristics that enable these features are:

• Bandwidth range: 500 MHz to 1.3 GHz; pulse duration: < 2 ns
• 用于安全通信的乱乱时间戳序列（STS）
• Mean pulse repetition frequency (PRF) from 3.9 MHz to 249.6 MHz for different channel conditions, and a peak PRF of 499.2 MHz
• Custom modulation schemes and guard intervals to avoid interference and multipath effects
• Single error correction and double error detection (SECDED) coding for the preamble, and Reed-Solomon coding for payload, with a convolutional code of ½ rate and a constraint length of 3 or 7

UWB.with MATLAB

您可以使用matlab^®Communications Toolbox™ for Zigbee^®and UWB Libraryto implement and test UWB features with reference examples shipped as openMATLAB代码。您可以使用MATLAB实现最新的超宽带修改（15.4z）或以前的15.4a。您还可以使用MATLAB使用UWB波形生成，端到端UWB收发器模拟和定位和测距示例来模拟各种本地化和测距算法。

UWB规格

首先提出了UEEE标准802.15.4a的修正案15.4a的超宽带规格。该修正案规定了高速脉冲重复频率（HRP）物理层（PHY），然后在修正15.4f中引入低速率脉冲重复频率（LRP）PHY。最新的增强提出了5.4z的修改，为此提供了增强功能的设备和安全功能的模式，以及此处的现有HRP和LRP-phy。

MATLAB provides examples that implement the following modes:

• 基本脉冲重复频率（BPRF），平均prf为62.4 mHz
• 高脉冲重复频率（HPRF），其中平均PRF为124.8 MHz或249.6 MHz

The scrambled timestamp sequence (STS) field is a security feature introduced by IEEE standard 802.15.4z to enhance data integrity. Transmission of the STS field is optional for the BRPF and HPRF modes.

Figure 1 shows the symbol and modulation scheme for 802.15.4a. The systematic bit of the convolutional coder is used to identify one of the two possible burst position modulation intervals (T_BPM）。传输可以仅在第一或第三个季度发生。蔓延后N._CPB（每个突发的芯片），奇偶校验位用于用二进制相移键控（BPSK）调制超宽带脉冲。使用从扩展序列构造的整数值来识别突发位置。每次传输都会通过保护间隔填充。Matlab示例HRP UWB IEEE 802.15.4a / z波形生成models these aspects of the signal.

Table 1 compares the UWB amendments of IEEE standard 802.15.4.

Table 1. UWB standards.

UWB收发器

Figure 2 shows a UWB transceiver. The transmitter chain consists of a PHY header that contains information such as data rate, frame length, and preamble duration. The PHY header is encoded by SECDED. Payload received by the upper layer is encoded using Reed-Solomon encoding. Standard 802.15.4z adds an optional STS field for data integrity. Another block of the convolutional encoder of rate ½ and a constraint length of 3 or 7 encodes the concatenated bitstream before conversion to complex symbols by a symbol mapper, which also spreads bits using a spreading sequence and chip length. After pulse shaping, the ultra-wideband signal is transmitted over the air. You can find an implementation of these steps atHRP UWB IEEE 802.15.4a / z波形生成。

The UWB receiver is a simple energy detector, implemented as a mirror image of the transmitter with the first block as an integrate-and-dump filter. You can find the complete transceiver implementation at theHRP UWB IEEE 802.15.4a / z phy的端到端模拟。

UWB本地化和测距

MATLAB支金宝app持使用与IEEE 802.15.4标准和IEEE 802.15.4z修正案兼容的媒体访问控制（MAC）和PHY帧的本地化和测距技术。三种广泛实现的测距技术是：

• 单面双向测距（SS-TWR）：一个设备估计在无线802.15.4z链路的两个方向上使用帧传输的两个设备之间的距离
• 双面双向测距（DS-TWR）：两个设备在无线802.15.4z链路的两个方向上使用帧传输估计两个设备之间的距离
• One-way ranging/time difference of arrival (OWR/TDOA): Network-assisted localization whereby one device communicates with a set of synchronized nodes to estimate the position of the device

You can find MATLAB examples of SS-TWRat UWB Ranging Using IEEE 802.15.4z,和owr / tdoa在使用IEEE 802.15.4z的UWB本地化。

在OWR /目标辐射源,设备本地化的期刊ly broadcasts short messages referred to as blinks. The TDOA between the periodic messages places the device in one hyperbolic surface for each pair of synchronized nodes. The intersection of all hyperbolic surfaces (over every pair of synchronized nodes) gives the location estimate for the device.

Figure 3 shows the results of an OWR/TDOA simulation in MATLAB.

Why Is UWB Important?

• UWB.provides an alternative physical layer for personal and body area networks that mainly functions in the 3.1 to 10.6 GHz range, which is less congested than the ISM (industrial, scientific and medical) band
• UWB.has low susceptibility to multipath fading, can work with low signal-to-noise ratios, and provides additional support for secure communications
• 与超级外差收发器架构相比，UWB提供系统简单性，并且通过高频使能的小天线可以在芯片内制造
• UWB脉冲持续时间比其他技术的符号次数短得多，支持测距和定位的高精度和低延迟，如表2所示金宝app

表2.比较用于测距和本地化的技术。