WSN 无线传感器网络复习提纲 整理版3.0

1.2 Application examples

1.4 Application examples

1.disaster relief applications

2.environment control and biodiversity mapping

3.intelligent buildings

4.facility management

5.machine surveillance and preventive maintenance

6.percision agriculture

7.medicine and health care

8.logistics

9.telematics

understand the challenges of WSNs:1.4

WSN的挑战性

1.4 challenges for WSNs

1.4.1characteristic requirements：要求的特性

1.Type of service

2.Quality of Service

3.Fault tolerance

4.Lifetime

5.Scalability

6.Wide range of densities

7.Programmability

8.Maintainability

1.4.2required mechanisms:要求机制

Some of the mechanisms that will form typical parts of WSNs are:

1.Multihop wireless communication

2.Energy-efficient operation

3.Auto-configuration

4.Collaboration and in-network processing

5.Data centric

6.Locality

7.Exploit trade-offs

understand the differences between WSNs and other networks:

1.5 为什么说传感器是不同的

1.5Why are sensor networks different?

1.5.1Mobile ad hoc networks and wireless sensor networks

（移动Ad hoc网络与无线传感器网络）

1.Applications, equipment: MANETs more powerful (read: expensive)

equipment assumed, often “human in the loop”-type applications, higher

data rates, more resources

2.Application-specific: WSNs depend much stronger on application specifics;

MANETs comparably uniform

3.Environment interaction: core of WSN, absent in MANET

4.Scale: WSN might be much larger (although contestable)

5.Energy: WSN tighter requirements, maintenance issues

6.Dependability/QoS: in WSN, individual node may be dispensable (network

matters), QoS different because of different applications

7.Data centric vs. id-centric networking

8.Mobility: different mobility patterns like (in WSN, sinks might be mobile,

usual nodes static)

1.5.2Wireless fieldbuses and WSNs（现场总线与无线传感器网络）Differences：

1.Scale – WSN often intended for larger scale

2.Real-time –WSN usually not intended to provide (hard) real-time

guarantees as attempted by fieldbuses

understand the enabling technologies for WSNs application

1.6无线传感器网络的技术要求

1.miniaturization of hardware

2 processing

https://www.360docs.net/doc/8315560028.html,munication

1.2 Application examples:应用领域

Disaster relief applications, Environment control and biodiversity mapping, Intelligent buildings, Facility management, Machine surveillance and preventive maintenance, Precision agriculture, Medicine and health care, Logistics, Telematics.

1.3types of application:区分应用类型

1.Event detection

2.Periodic measurements

3.Function approximation and edge detection

4.Tracking

第二章：2.1.1，2.1.4,2.1.5，p37,43,2.2.5,2.3.2,2.3.5,

Basic requirement:

master the hardware components of sensor nodes

2.1节点的硬件组成

2.1 hardware components: 硬件组成部分

?Main components of a WSN node

?Controller

?Communication device(s)

?Sensors/actuators

?Memory

?Power supply

2.1.4 communication device

Transceiver operational states:收发机的四个状态

?Transceivers can be put into different operational states, typically:

?Transmit -- In the transmit state, the transmit part of the transceiver is active and the antennaradiates energy.

?Receive -- In the receive state the receive part is active.

?Idle– ready to receive, but not doing so

?Some functions in hardware can be switched off, reducing

energy consumption a little

?Sleep– significant parts of the transceiver are switched off

?Not able to immediately receive something

?Recovery time and startup energy to leave sleep state can be

significant

无线传感器的微控制器也有三个状态（活跃期，空闲期，睡眠期），两者有区别！

2.1.5sensors: 传感器的分类

Passive, omnidirectional sensors被动全向传感器温湿度传感器等

Typical examples for such sensors include thermometer, light sensors, vibration microphones, humidity, mechanical stress or tension in materials,

chemical sensors sensitivefor given substances, smoke detectors, air

pressure, and so on.

●Passive, narrow-beam sensors被动、窄束照相机等

A typical example is a camera, which can “take measurements”in a given

direction, but has to be rotated if need be.

●Active sensors主动雷达声呐等

For example, a sonaror radar sensor or some types of seismic sensors, which generate shock waves by smallexplosions.

understand the energy consumption of component module

2.2 energy consumption of sensor nodes

注意区分每一个硬件部分的能量分析，哪一部分是比较针对微控制器的能量分析（whether put into sleep mode should be taken to reduce power consumption）、哪一部分是比较针对收发机、哪一部分是比较针对计算传输等

节约能量时会用到：

调整控制器的功率消耗时DVS

收发机能耗，与调制结合，DMS（动态调制调整）（从DVS出发的）

DCS动态码调整

DMCS动态调制码调整

计算和通信之间能量消耗的关系

a controller, typical states are “active”, “idle”, and “sleep”; a radio modem could turn transmitter,receiver, or both on or off; sensors and memory could also be turned on or off. The usual terminologyis to speak of a “deeper” sleep state if less power is consumed。

耗能主体1.controller 2.radio frontends 3.memory

2.2.3 Memory 存储器

On-chip memory of a microcontroller and FLASH memory

2.3 节点的操作系统与运行环境

2.3 Operating systems and execution environments

无线传感器网络OS基于事件的，而非基于进程的

Operating system: Event-based programming 基于事件

Protocol stacks : component-based 基于部件

Typical OS: Tiny OS

Event-based programming

The idea is toembrace the reactive nature of a WSN node and integrate it into the design of the operatingsystem. The system essentially waits for any event to happen, where an event typically can be theavailability of data from a sensor, the arrival of a packet, or the expiration of a timer. Such anevent is then handled by a short sequence

of instructions that only stores the fact that this eventhas occurred and stores the necessary information –for example, a byte arriving for a packet or thesensor’s value –somewhere. The actual processing of this information is not done in these eventhandler routines, but separately, decoupled from the actual appearance of events. This event-basedprogramming [353] model is sketched in Figure 2.8.

understand properties of different nodes.

2.4 传感器节点的一些例子

第三章选、判、填

Basic requirement:

understand the Sensor network scenarios

3.1 传感器网络工作场景

3.1.1 types of sources and sinks(信宿)

A source is any entity in the network that can provide information, this is, typically a sensor node; it could also be an actuator node that provides feedback about an operation.

A sink is entity where information is required. It belong to the sensor network ; be just another sensor/actuator node; be an entity outside this network.

3.1.2 Multihop networks

Because of this limited distances. Store and forward.障碍物obstacle

3.1.4 three types of mobility

Node mobility: the wireless sensor nodes themselves can be mobile. environmental control will not happen.

Sink mobility: the information sinks can be mobile. While this can be a special case of node mobility. The important aspect is the mobility of an information sink that is not part of the sensor network.

Event mobility: In applications like event detection and in particular in tracking applications, the cause of the events or the objects to be tracked can be mobile.

master the design principles of WSNs：

3.3 WSN设计原则

3.3 Design principles for WSNs

Appropriate QoS support, energy efficiency, and scalability are important design and optimizationgoals for wireless sensor networks.

在构建WSN结构时的设计原则：

●分布式组织Distributed organization

●网络内部处理自适应的保真度与精度In-network processing Adaptive fidelity and

accuracy

●以数据为中心data centricity

●利用位置信息Exploit location information

●利用主动模式Exploit activity patterns

●利用多样性Exploit heterogeneity

●基于部件的协议栈与层的优化Component-based protocol stacks and cross-layer

oprimization

分布式组织，

3.3.1 Distributed organization

Both the scalability and the robustness optimization goal, and to some degree also the other goals,make it imperative to organize the network in a distributed fashion. That means that there shouldbe no centralized entity in charge –such an entity could, for example, control medium access ormake routing decisions, similar to the tasks performed by a base station in cellular mobile networks.The disadvantages

of such a centralized approach are obvious as it introduces exposed points offailure and is difficult to implement in a radio network, where participants only have a limitedcommunication range. Rather, the WSNs nodes should cooperatively organize the network, usingdistributed algorithms and protocols. Self-organization is a commonly used term for this principle.

When organizing a network in a distributed fashion, it is necessary to be aware of potentialshortcomings of this approach. In many circumstances, a centralized approach can produce solutionsthat perform better or require less resources (in particular, energy). To combine the advantages,one possibility is to use centralized principles in a localized fashion by dynamically electing, outof the set of equal nodes, specific nodes that assume the responsibilities of a centralized agent, forexample, to organize medium access. Such elections result in a hierarchy, which has to be dynamic:The election process should be repeated continuously lest the resources of the elected nodes beovertaxed, the elected node runs out of energy, and the robustness disadvantages of such –even onlylocalized –hierarchies manifest themselves. The particular election rules and triggering conditionsfor reelection vary considerably, depending on the purpose for which these hierarchies are used.

网内处理：

3.3.2 In-network processing网络内部处理

1.Aggregation

2. distributed source coding and distributed compression

3. distributed and collaborative signal processing

4. mobile code/Agent-based networking

Distributed source coding and distributed compression

聚合aggregation 搞清原理网内信息处理

Aggregation P68

3.3.4 Data centriciy

1. address data, note nodes

2. Implementation options for data-centric networking

1.Overlay networks and distributed hash tables(peer-to-peer)

2.publish/subscribe Any node interested in a given kind of data can subscribe to it,

and any node can publish data, along with information abut its kind as well.

3.Databases(数据库)

understand the gateway concepts.

3.5 网关的概念

3.5 Gateway concepts

provides the physical connection to the Internet提供物理连接

regard a gateway as a simple router between Internet and sensor network

因特网与传感器网络之间的简单路由

第四章物理层

master the wireless channel and communication fundamentals,

4.2 无线信道的通信基础

4.2.1 Frequency allocation

Frequency band ISM

433-464MHz Europe

902-928MHz Americas

2.4-2.5GHz WLAN/WPAN

5.725-5.875GHz WLAN

4.2.2 区分symbol rate 和data rate

●Symbol rate

●The symbol rate is the inverse of the symbol duration; for binary modulation, it

is also called bit rate.

Data rate

The data rate is the rate in bit per second that the modulator can accept for transmission;it is thus the rate by which a user can transmit binary data. For binary modulation, bit rateand data rate are the same and often the term bit rate is (sloppily) used to denote the datarate.

4.2.3 path loss and attenuation 路径损耗和衰减

Wireless waveforms propagating through free space are subject to a distance-dependent loss of power, called path loss. Attenuation because of transmitted in some media, not in the vacuum.

P97 WSN信道模型

WSN-specific channel models

Since in addition the data rates are moderate, it is reasonable to expect frequency nonselective fading channels with noise and a low-to-negligible degree of ISI. Accordingly, no special provisions against ISI like equalizers are needed.典型的信道模型：频率非选择性衰弱信道，并且可以忽略符号间干扰

4.2.3 Wave propagation effects and noise

4.2.4 channel models

understand physical layer and transceiver design

considerations in WSNs.

4.3WSN物理层和收发机设计考虑

4.3.1

能量使用的特点（作业）：辐射的能量的影响；发射能量和接收能量的比较；启动能量、启动时间

●the radiated energy is small；the overall transceiver (RF front end and baseband

part) consumes much more energy than is actually radiated辐射能量较小。

●for small transmit powers the transmit and receive modes consume more or less

the same power；it is even possible that reception requires more power than transmission; depending on the transceiver architecture, the idle mode’s power consumption can be less or in the same range as the receive power。基本相同●startup energy/startup time，a transceiver has to spend upon waking up from

sleep mode。Startup energy/time penalty can be high

4.3.3 Dynamic modulation scaling 108页

动态调制调整：原理

如果增加B和m的值，比特延迟会减小，每个比特的能量消耗主要取决于m，与B也有关，事实上，对于特别的参数选取，已经表明，当符号率最大时，每个比特消耗的能量和每个比特的延迟是最小的。分组数增加，m增加

Antenna

第五章

Basic requirement:

master the fundamentals of MAC protocols

5.1 无线MAC协议的基础知识

113 隐藏终端、暴露终端

The hidden-terminal problem occurs specifically for the class of Carrier Sense MultipleAccess (CSMA) protocols, where a node senses the medium before starting to transmit a packet.

Using simple CSMA in an exposed terminal scenario thus leads to needless waiting.

5.1.2 114页MAC协议的分类

●固定配置协议Fixed assignment protocols

●按要求配置协议demand assignment protocols

●随机接入协议random access protocols

116 解决隐藏终端的手段2个

●the busy-tone solution忙音技术

●the RTS/CTS handshake握手技术

5.1.2 important classes of MAC protocols

1.Fixed Assignment protocols 固定配置协议TDMA FDMA CDMA SDMA(不能)

2.Demand assignment protocols 按需分配的协议LEACH

3.Random access protocols 随机接入协议ALOHA slotted ALOHA(higher through put) CSMA Nonpersistent CSMA backoff algorithm busy-tone solution 解决了隐藏终端和暴露终端的问题，与数据传输距离相同之处能侦听到忙音信号。

RTS/CTS握手方法基于WACAW协议一个信道两个控制分组

RTS请求发送CTS清除发送Data数据Ack确认将一个较大的分组拆分为几个较小的分组保证cts比rts长

119 5.1.3

MAC层的能量问题

?Collisions碰撞– wasted effort when two packets collide

fixed assignment/TDMA or demand assignment protocols，CSMA protocols

?Overhearing偷听– waste effort in receiving a packet destined for another node ?Idle listening空闲监听– sitting idly and trying to receive when nobody is sending TDMA-based protocols

?Protocol overhead协议开销Protocol overhead is induced by MAC-related control frames like, for example,RTS and CTS packets or request packets in demand assignment protocols,

understand the low duty cycle protocols and wakeup concepts,

5.2低占空比协议与唤醒的概念

每个协议针对能量问题的算法的区分，最突出，最不同的点

S-MAC

SMACS

占空比=侦听阶段/唤醒周期

Avoid spending much time in the idle state and to reduce the communication activities of a sensor node to a minimum.

大部分时间处于休眠状态并周期性的被唤醒来接收来自其他节点的分组periodic wakeup 周期性唤醒掌握发送目标的监听时段

5.2.4 wakeup radio concepts无线唤醒的概念

节点发送或者接受或者休眠不存在空闲状态FDMA低功耗唤醒收发机处于经常工作的状态信道空闲收到唤醒信号唤醒数据收发机有通信量自适应功能负载增加MAC越来越活跃

understand contention and schedule based protocols, 5.3 基于竞争的协议

5.3

哪些是基于竞争的协议contention-based ALOHA、CSMA

哪些基于调度表协议schedule-based LEACH SMACS TRAMA

哪些基于分配的协议

5.4 基于时间的协议

5.4.1

LEACH 自适应的低功耗的分簇算法LEACH协议将一个基于TDMA的MAC协议与聚类协议和一个简单的“路由”协议集成在一起分簇簇头节点负责确定和维护TDMA时间表对成员节点分配TDMA时隙能量消耗大每个成员节点轮流担任簇头节点簇头节点在网络节点中所占的百分比是一个有用的网络参数

重点

CSMA

RPS

CTS

master the IEEE 802.15.4 MAC protocol.

5.5.1

Network architecture and types/roles of nodes

一个标准的MAC层分为两种不同的节点

1.全功能设备FFD PAN网络协调器简单协调器设备三种功能

2.精简功能设备RFD 只用作设备

一个设备必须与一个协调器一起工作并仅与其进行通信构成一个星状网络协调器可以工作于对等模式

协调器完成四个任务

超帧的结构IEEE 802.15.4

活跃时段不活跃时段

信标竞争介入时段保障时隙

节点在CAP时段必须发送数据分组或管理控制分组时采用Slotted CSMA-CA protocol CSMA protocol

区别不包含关于隐藏终端的规定使用随机延迟使用带有碰撞避免的CSMA协议回退时段Basic requirement:

understand the role and significance of the time synchronization problem,

8.1 理解时间同步问题的概念和意义

202 各个时间的概念

物理时间大多数应用和协议都要求物理时间

逻辑时间分布式系统中事件发生的顺序关系

●physical time = wall clock time, real-time, coordinated universaltime (UTC)

●logical time：allows to determine the ordering of events in a distributed system

but does not necessarily show any correspondence to real time

8.1.2 Node clocks and the problem of accuracy 203

?External synchronization:

?synchronization with external real time scale like UTC

?Nodes i=1, ..., n are accurate at time t within bound d when|L i(t) – t|

?No external timescale, nodes must agree on common time

?Nodes i=1, ..., n agree on time within bound d when |L i(t) – L j(t)|

?Metrics:

?Precision: maximum synchronization error for deterministic algorithms, error mean / stddev / quantiles for stochastic ones

?Energy costs, e.g. # of exchanged packets, computational costs

?Memory requirements

?Fault tolerance: what happens when nodes die?

8.2基于发送/接收的时间同步协议

8.2 Protocols based on sender/receiver synchronization 207 基于

公共步骤1.成对同步 2.全网同步

Lightweight time synchronization protocol LTS

比对同步协议完成两个相邻节点的同步

建立一个从参考节点到所有节点的层次最少的生成树

发送接收的同步计算方法计算题作业

分布式多跳LTS 不需要构造生成树每个节点需要知道许多参考节点并沿着适当的路径到达他们这些参考节点的责任就是周期性的启动再同步

8.2.3 Time-Sync for sensor networks TPSN

非对称i可以与j但是反过来不行

8.3基于接收/接收的时间同步协议

8.3.1 Reference broadcast synchronization(RBS)参考广播同步

多跳范围内的网络同步

Network synchronization over multiple hops

多广播域RBS 不断变换时间确保最后到达信宿的时间是准确的以UTC时间表示

Basic requirement:

understand the properties of localization and positioning procedures,

9.1 9.2 WSN定位网络的特点和方法

9.1 Properties of localization and positioning procedures

●Physical position versus symbolic location

●Absolute versus relative coordinates

●Localized versus centralized computation

●Accuracy and precision

Accuracy：估计值与实际值的最大距离

Precision：达到准确性的百分比

●Scale

●Limitations

●Costs

9.2定位的三种方法Possibleapproaches

1. Proximity 利用相邻节点的信息进行定位

2.Trilateration and triangulation 三边定位和三角定位

Determiningdistances

三种测距方法RSSI TOA TDOA

3.Scene analysis情景分析

9.3Mathematical basicsfor the lateration problem 测边定位

understand the differences between the single-hop and multihop localizations,

9.49.5 单跳定位与多跳定位的区别

9.4.6 Approximate point in triangle近似三角形内点测试法

对于所有的邻居节点，如果三个顶点到邻居节点的距离没有同时更近或更远，那么未知节点在三角形内，否则在三角形外。

understand the impact of anchor placement.

9.5

DV HOP：9.5.2 P245

?Count number of hops, assume length of one hop is known (DV-Hop) ?Start by counting hops between anchors, divide known distance

?If range estimates between neighbors exist, use them to improve total length of route estimation in previous method (DV-Distance)

计算任何两个锚节点的跳数并用总长度除以总跳数来估算单跳的平均长度，每个锚节点都计算单跳平均长度并向网络中广播，未知节点利用平均单跳长度来估计多跳距离，然后利用多边交叉法定位。

9.6 锚节点的配置对定位的影响

概念

递进式Iterative multilateration

?Assume some nodes can hear at least three anchors (to perform triangulation), but not all

?Idea: let more and more nodes compute position estimates, spread position knowledge in the network

?Problem: Errors accumulate

协作式collaborative multilateration

递进式可能产生2个解participating nodes

10.1拓扑控制算法

以G=(V,E)代表网络V是网络中所有节点的集合当且仅当v1 v2有直接通信时，边Ev1-v2存在区分主干网络和分簇式网络采用骨干节点来限制网络拓扑结构普通节点和骨干节点之间只有一跳

利用簇来划分一个图和骨干节点不同的是，每一个簇都是分开的

P263 双向联通的最小最大功率的集中式算法

最小发射功率的连通性贪婪算法

逐渐增大发射功率找到最小发射功率继续增大，剔除每个节点最大发射功率的边P266 采用控制集的层次型网络

P267 growinga tree dominating sets

随机选取一个白色节点涂成灰色，如果灰色节点的邻居节点有白色，则升级他们为黑色节点，并将其邻居节点改为灰色。

P271 Marking nodes with unconnected neighbors

●A nonoptimal connected dominating set construction

●Two pruning heuristics 修剪启发式算法

10.4 Hierarchical networks by clustering 分簇式层次型网络见PPT ?Construct clusters

?Partition nodes into groups (“clusters”)

?Each node in exactly one group

?Except for nodes “bridging” between two or more groups

?Groups can have clusterheads

?Typically: all nodes in a cluster are direct neighbors of their clusterhead

?Clusterheads are also a dominating set, but should be separated from each other – they form an independent set

?Formally: Given graph G=(V,E), construct C ? V such that

10.6.1 Geographic Adaptive Fidelity(GAF)基于地理位置的拓扑算法

任意两个节点可以互相代替

11.1 路由协议的功能和目标

11.3 能量高效型单播

根据不同的能效目标计算路由路径

?Minimize energy/bit: A-B-E-H

?Maximum total available battery capacity

?Path metric: Sum of battery levels

?Example: A-C-F-H

?Minimum battery cost routing

?Path metric: Sum of reciprocal battery levels

?Example: A-D-H

1.每个分组的最小能量

2.网络生存周期最长（选用可用电池能量最高的路径）

3.最大总可用电池容量

4.最小电池消耗路由选择

5.最小-最大电池消耗路由

11.3.4 multipath unicast routing 多路径单播路由建立能量高效的辅助路径

一些简单的转发策略

1.在r内向最远处转发

2.向最近的节点转发

3.定向路由

4.死胡同问题解决：GPSR 右手法则重建贪婪路由基于平面

5.受限泛洪

11.4 广播与多播

11.4.1 Broadcast & multicast

?Distribute a packet to all reachable nodes (broadcast) or to a somehow (explicitly) denoted subgroup (multicast)

?Basic options

?Source-based tree: Construct a tree (one for each source) to reach all addressees

?Minimize total cost (= sum of link weights) of the tree

?Minimize maximum cost to each destination

?Shared, core-based trees

?Use only a single tree for all sources

?Every source sends packets to the tree where they are distributed ?Mesh

?Trees are only 1-connected ! use meshes to provide higher redundancy and thus robustness in mobile environments

P310 Broadcast incremental power (BIP)功率递增广播

?How to broadcast, using the wireless multicast advantage?

?Goal: use as little transmission power as possible

?Idea: Use a minimum-spanning-tree-type construction (Prim’s algorithm)

?But: Once a node transmits at a given power level & reaches some neighbors, it becomes cheaper to reach additional neighbors

13.1 WSN的传输层和服务质量

understand the conditions of reliable data transportation, 13.3可靠数据传输

Guaranteed versus stochastic delivery,

可靠传递所有期望的传输分组到达目的地

随机传递允许存在一定程度的损失

13.4.1usinga single path

1.who detectslosses and what are the indicators used

2.who requests retransmissions

3.who carries out these retransmissions

13.5 Block delivery

Handing an out-of-order packet

13.6拥塞控制和数据率控制

402 congestion 拥塞控制的概念和处理方法

Congestion handling

?Option 1: Drop packets

?No alternative anyways when buffers overflow

?Drop tail, random (early) drop (for TCP), …

?Better: drop semantically less important packet ?Option 2: Control sending rateof individual node

?Rate of locally generated packets

?Rate of remote packets to be forwarded —backpressure ?Option 3: Control how many nodes are sending

?Option 4: Aggregation, in-network processing

404 图13.27