【 Notes 】COMPARISON OF BASIC METHODS AND POSITIONING SYSTEMS

COMPARISON OF BASIC METHODS AND POSITIONING SYSTEMS

CONCLUSION, SUMMARY, AND FUTURE APPLICATIONS

COMPARISON OF BASIC METHODS AND POSITIONING SYSTEMS

各种基本方法以及定位系统的对比：

This section compares basic localization methods and positioning systems in Tables 1.1 and 1.2 .

Several positioning parameters are used to compare different methods.

基本定位方法精度的标度：高（H），0 - 50; 中（M），50-100; 低（L），> 100。

Table 1.1 compares basic positioning methods previously discussed in the chapter in terms of accuracy, a need for the availability of LOS, and the number of base stations required for localization.

表1.1比较了本章前面讨论的基本定位方法的准确性，对LOS可用性的需求以及定位所需的基站数量。

The table shows that on average, the accuracy of the DOA estimate is poorer relative to TOA, TDOA, and RSSI estimates. This is mainly due to the fact that as the distance between the base station and the target increases, a small DOA error leads to a higher localization error. The DOA error is very sensitive to the multipath environment and the signal - to - noise ratio [23] .

该表显示，平均而言，相对于TOA，TDOA和RSSI估计，DOA估计的准确性较差。这主要是由于随着基站和目标之间的距离增加，小的DOA误差导致更高的定位误差。 DOA误差对多径环境和信噪比非常敏感[23]。

Complex algorithms could be used to improve the DOA performance. DOA performance in localization methods such as WLPS can be improved by incorporating its periodic transmission nature [24, 25] .

复杂算法可用于改善DOA性能。通过结合其周期性传输特性，可以改善诸如WLPS的定位方法中的DOA性能[24,25]。

RSSI is different from other methods when the availability of LOS is taken into account, since it operates in both LOS and NLOS environments. Other localization techniques are very sensitive to the availability of LOS.

当考虑LOS的可用性时，RSSI与其他方法不同，因为它在LOS和NLOS环境中都运行。其他定位技术对LOS的可用性非常敏感。

Table 1.2 compares different positioning systems based on several parameters.
The following observations can be made from the table:
• Most of the systems that operate based on the availability of LOS propagation have higher accuracy. Thus, NLOS introduces error in the calculation, decreasing the accuracy.
• Many existing positioning systems employ multiple base nodes to localize the target node. This may create a system cost problem for the designer.
• The power consumption for most positioning systems is medium to very low. Thus, using one of the low - power positioning systems does not impose additional constraint on the designer with respect to the required power consumption.
• All positioning systems except RFID - based systems can support mobility.
• Many positioning systems are well suited for both outdoor and indoor environments.

•基于LOS传播可用性运行的大多数系统具有更高的准确性。因此，NLOS在计算中引入误差，降低了精度。
•许多现有定位系统使用多个基节点来定位目标节点。这可能会给设计人员带来系统成本问题。

•大多数定位系统的功耗从中到低。因此，使用低功率定位系统之一不会对设计者施加额外的约束，即所需的功耗。
•除基于RFID的系统外，所有定位系统均可支持移动性。
•许多定位系统非常适合室外和室内环境。

Scale for accuracy of positioning systems: very high (VH), < 1; high (H), 1 – 5; medium (M), 5 – 30; low (L), 30 – 50; very low (VL), > 50.

定位系统精度的标度：非常高（VH），<1; 高（H），1 - 5; 中（M），5 - 30; 低（L），30 - 50; 非常低（VL），> 50。

Scale for power consumption of positioning systems: very low (VL), < 1; low (L), 1 – 10; moderate (M), 10 – 50; high(H), 50 – 200; very high (VH), > 200.

定位系统功耗的标度：非常低（VL），<1; 低（L），1 - 10; 中度（M），10 - 50; 高（H），50 - 200; 非常高（VH），> 200。

c:
The initial accuracy is high (few decimeters), which changes with time due to error propagation.

初始精度很高（几个分米），由于误差传播而随时间变化。

d:
Depends on INS classification (stable platform system consumes high power; strapdown system consumes moderate power).

取决于INS分类（稳定平台系统消耗高功率;捷联系统消耗中等功率）。

e:
The initial accuracy is low (few degrees), which decreases with distance.

初始精度很低（几度），随着距离的增加而减小。

f:
The detection range of the vision system is 1 – 95 m, which determines the accuracy.

视觉系统的检测范围是1-95米，这决定了准确性。

g:
Within the high range, the power consumption depends on the peak power output.

在高范围内，功耗取决于峰值功率输出。

h:
In GPS and AGPS, satellites are considered as base stations.

在GPS和AGPS中，卫星被视为基站。

O, outdoor; I, indoor; N/A, not applicable.

CONCLUSION, SUMMARY, AND FUTURE APPLICATIONS

Figure 1.5 Futuristic applications of positioning systems.

The existing positioning systems are used in numerous applications that will likely be expanded in the future, in response to new demands. As shown in Figure 1.5 , the future entails collaboration among various positioning systems especially for applications related to situation awareness.

现有的定位系统被用于许多应用中，这些应用将来可能会根据新的需求进行扩展。如图1.5所示，未来需要各种定位系统之间的协作，特别是与情境感知相关的应用。

For example, in the case of an automatically driven car, the information on the road condition and traffic (situation awareness) may be obtained using various existing positioning systems such as GPS, radar [38] , and WLPS. As shown in the figure, the automatically driven car can derive information such as the distance of the surrounding traffi c using radar and WLPS. GPS can help the automatically driven car to recognize roadblocks caused by accident or other factors such as traffi c. Thus, in this example, the automatically driven car can be aware of its situation using the positioning technologies.

例如，在自动驾驶汽车的情况下，可以使用诸如GPS，雷达[38]和WLPS之类的各种现有定位系统来获得关于道路状况和交通（情况感知）的信息。如图所示，自动驾驶汽车可以使用雷达和WLPS获得诸如周围交通的距离之类的信息。 GPS可以帮助自动驾驶汽车识别由事故或其他因素（如交通）引起的路障。因此，在该示例中，自动驾驶汽车可以使用定位技术了解其情况。

In another example that is shown in the figure, a soldier on a reconnaissance or rescue mission can use the information from a vision system, radar, and GPS to be aware of his surroundings or situation. Also shown in the figure is the police car that keeps track of the thief and road conditions using signals from several positioning systems. Miners can also benefi t from the positioning systems such as INS and RFID to be aware of their current location and possible escape route in case of emergency. For the miners, it can be envisioned that RFID tags are installed along the mine tunnels as it is explored deeper in the earth ’ s crust. The information from these RFID tags can potentially include the depth of the mine, the soil characteristics, and so on.

在图中示出的另一示例中，侦察或救援任务中的士兵可以使用来自视觉系统，雷达和GPS的信息来了解他的周围环境或情况。图中还显示了使用来自多个定位系统的信号跟踪小偷和道路状况的警车。矿工还可以从INS和RFID等定位系统中获益，以便在紧急情况下了解其当前位置和可能的逃生路线。对于矿工来说，可以设想RFID标签沿着矿井隧道安装，因为它在地壳的深处探测。来自这些RFID标签的信息可能包括矿井的深度，土壤特征等。

Finally, also shown in the figure is a ship that gathers information from a number of systems and selects its course accordingly. It should be noted that the figure provides only some of the applications where positioning systems collaborate among themselves or with other systems (e.g., a weather forecast system) for situation awareness.

最后，图中还显示了一艘船，它从许多系统收集信息并相应地选择其路线。应当注意，该图仅提供了定位系统在它们之间或与其他系统（例如，天气预报系统）协作以用于情况感知的一些应用。

This handbook reviews the details of many localization techniques that have been briefl y introduced in this chapter.