372 lines
28 KiB
HTML
372 lines
28 KiB
HTML
|
|
|||
|
|
<!DOCTYPE html>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<html lang="en">
|
|||
|
|
<head>
|
|||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|||
|
|
|
|||
|
|
<title>5.7. Wireless Connectivity: Wi-Fi, Bluetooth, and Zigbee — Computer Systems Fundamentals</title>
|
|||
|
|
|
|||
|
|
<link rel="stylesheet" href="_static/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous" />
|
|||
|
|
<link rel="stylesheet" href="_static/css/pygments.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="_static/css/normalize.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="../../../JSAV/css/JSAV.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="../../../lib/odsaMOD-min.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="_static/css/jquery-1.11.4-smoothness-ui.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="../../../lib/odsaStyle-min.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="_static/css/csf.css" type="text/css" />
|
|||
|
|
|
|||
|
|
<style>
|
|||
|
|
.underline { text-decoration: underline; }
|
|||
|
|
</style>
|
|||
|
|
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
var DOCUMENTATION_OPTIONS = {
|
|||
|
|
URL_ROOT: './',
|
|||
|
|
VERSION: '0.4.1',
|
|||
|
|
COLLAPSE_INDEX: false,
|
|||
|
|
FILE_SUFFIX: '.html',
|
|||
|
|
HAS_SOURCE: true
|
|||
|
|
};
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<script type="text/x-mathjax-config">
|
|||
|
|
MathJax.Hub.Config({
|
|||
|
|
tex2jax: {
|
|||
|
|
inlineMath: [['$','$'], ['\\(','\\)']],
|
|||
|
|
displayMath: [ ['$$','$$'], ["\\[","\\]"] ],
|
|||
|
|
processEscapes: true
|
|||
|
|
},
|
|||
|
|
"HTML-CSS": {
|
|||
|
|
scale: "80"
|
|||
|
|
}
|
|||
|
|
});
|
|||
|
|
</script>
|
|||
|
|
<link rel="shortcut icon" href="_static/favicon.ico"/>
|
|||
|
|
<link rel="index" title="Index" href="genindex.html" />
|
|||
|
|
<link rel="search" title="Search" href="search.html" />
|
|||
|
|
<link rel="index" title="Computer Systems Fundamentals" href="index.html" />
|
|||
|
|
<link rel="next" title="8. Extended Example: DNS Client" href="Extended5DNS.html" />
|
|||
|
|
<link rel="prev" title="6. Link Layer" href="LinkLayer.html" />
|
|||
|
|
|
|||
|
|
</head><body>
|
|||
|
|
|
|||
|
|
<nav class="navbar navbar-expand-md navbar-dark navbar-custom fixed-top">
|
|||
|
|
|
|||
|
|
<a class="navbar-brand py-0" href="index.html"><img src="_static/CSF-Logo-Square-Text.png" alt="OpenCSF Logo" height="40em" class="py-1 px-2 mb-0 align-center rounded-lg bg-white" /></a>
|
|||
|
|
<!-- Show a navbar toggler on mobile -->
|
|||
|
|
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#defaultNavbars" aria-controls="defaultNavbars" aria-expanded="false" aria-label="Toggle navigation">
|
|||
|
|
<span class="navbar-toggler-icon"></span>
|
|||
|
|
</button>
|
|||
|
|
<div class="collapse navbar-collapse" id="defaultNavbars">
|
|||
|
|
<ul class="navbar-nav mr-auto">
|
|||
|
|
<li class="nav-item dropdown">
|
|||
|
|
<a class="nav-link dropdown-toggle jmu-gold rounded" href="Wireless.html#" id="navbarDropdownChapters" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Contents</a>
|
|||
|
|
<div class="dropdown-menu scrollable-menu" role="menu" aria-labelledby="navbarDropdownChapters">
|
|||
|
|
<a class="dropdown-item" tabindex="-1" href="Wireless.html#"><b>Chapter 1</b></a>
|
|||
|
|
<a class="dropdown-item" href="IntroConcSysOverview.html"> 1.1. Introduction to Concurrent Systems</a>
|
|||
|
|
<a class="dropdown-item" href="SysAndModels.html"> 1.2. Systems and Models</a>
|
|||
|
|
<a class="dropdown-item" href="Themes.html"> 1.3. Themes and Guiding Principles</a>
|
|||
|
|
<a class="dropdown-item" href="Architectures.html"> 1.4. System Architectures</a>
|
|||
|
|
<a class="dropdown-item" href="StateModels.html"> 1.5. State Models in UML</a>
|
|||
|
|
<a class="dropdown-item" href="SequenceModels.html"> 1.6. Sequence Models in UML</a>
|
|||
|
|
<a class="dropdown-item" href="StateModelImplementation.html"> 1.7. Extended Example: State Model Implementation</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 2</b></a>
|
|||
|
|
<a class="dropdown-item" href="ProcessesOverview.html"> 2.1. Processes and OS Basics</a>
|
|||
|
|
<a class="dropdown-item" href="Multiprogramming.html"> 2.2. Processes and Multiprogramming</a>
|
|||
|
|
<a class="dropdown-item" href="KernelMechanics.html"> 2.3. Kernel Mechanics</a>
|
|||
|
|
<a class="dropdown-item" href="Syscall.html"> 2.4. System Call Interface</a>
|
|||
|
|
<a class="dropdown-item" href="ProcessCycle.html"> 2.5. Process Life Cycle</a>
|
|||
|
|
<a class="dropdown-item" href="UnixFile.html"> 2.6. The UNIX File Abstraction</a>
|
|||
|
|
<a class="dropdown-item" href="EventsSignals.html"> 2.7. Events and Signals</a>
|
|||
|
|
<a class="dropdown-item" href="Extended2Processes.html"> 2.8. Extended Example: Listing Files with Processes</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 3</b></a>
|
|||
|
|
<a class="dropdown-item" href="IPCOverview.html"> 3.1. Concurrency with IPC</a>
|
|||
|
|
<a class="dropdown-item" href="IPCModels.html"> 3.2. IPC Models</a>
|
|||
|
|
<a class="dropdown-item" href="Pipes.html"> 3.3. Pipes and FIFOs</a>
|
|||
|
|
<a class="dropdown-item" href="MMap.html"> 3.4. Shared Memory With Memory-mapped Files</a>
|
|||
|
|
<a class="dropdown-item" href="POSIXvSysV.html"> 3.5. POSIX vs. System V IPC</a>
|
|||
|
|
<a class="dropdown-item" href="MQueues.html"> 3.6. Message Passing With Message Queues</a>
|
|||
|
|
<a class="dropdown-item" href="ShMem.html"> 3.7. Shared Memory</a>
|
|||
|
|
<a class="dropdown-item" href="IPCSems.html"> 3.8. Semaphores</a>
|
|||
|
|
<a class="dropdown-item" href="Extended3Bash.html"> 3.9. Extended Example: Bash-lite: A Simple Command-line Shell</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 4</b></a>
|
|||
|
|
<a class="dropdown-item" href="SocketsOverview.html"> 4.1. Networked Concurrency</a>
|
|||
|
|
<a class="dropdown-item" href="FiveLayer.html"> 4.2. The TCP/IP Internet Model</a>
|
|||
|
|
<a class="dropdown-item" href="NetApps.html"> 4.3. Network Applications and Protocols</a>
|
|||
|
|
<a class="dropdown-item" href="Sockets.html"> 4.4. The Socket Interface</a>
|
|||
|
|
<a class="dropdown-item" href="TCPSockets.html"> 4.5. TCP Socket Programming: HTTP</a>
|
|||
|
|
<a class="dropdown-item" href="UDPSockets.html"> 4.6. UDP Socket Programming: DNS</a>
|
|||
|
|
<a class="dropdown-item" href="AppBroadcast.html"> 4.7. Application-Layer Broadcasting: DHCP</a>
|
|||
|
|
<a class="dropdown-item" href="Extended4CGI.html"> 4.8. Extended Example: CGI Web Server</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 5</b></a>
|
|||
|
|
<a class="dropdown-item" href="InternetOverview.html"> 5.1. The Internet and Connectivity</a>
|
|||
|
|
<a class="dropdown-item" href="AppLayer.html"> 5.2. Application Layer: Overlay Networks</a>
|
|||
|
|
<a class="dropdown-item" href="TransLayer.html"> 5.3. Transport Layer</a>
|
|||
|
|
<a class="dropdown-item" href="NetSec.html"> 5.4. Network Security Fundamentals</a>
|
|||
|
|
<a class="dropdown-item" href="NetLayer.html"> 5.5. Network Layer: IP</a>
|
|||
|
|
<a class="dropdown-item" href="LinkLayer.html"> 5.6. Link Layer</a>
|
|||
|
|
<a class="dropdown-item" href="Wireless.html"> 5.7. Wireless Connectivity: Wi-Fi, Bluetooth, and Zigbee</a>
|
|||
|
|
<a class="dropdown-item" href="Extended5DNS.html"> 5.8. Extended Example: DNS client</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 6</b></a>
|
|||
|
|
<a class="dropdown-item" href="ThreadsOverview.html"> 6.1. Concurrency with Multithreading</a>
|
|||
|
|
<a class="dropdown-item" href="ProcVThreads.html"> 6.2. Processes vs. Threads</a>
|
|||
|
|
<a class="dropdown-item" href="RaceConditions.html"> 6.3. Race Conditions and Critical Sections</a>
|
|||
|
|
<a class="dropdown-item" href="POSIXThreads.html"> 6.4. POSIX Thread Library</a>
|
|||
|
|
<a class="dropdown-item" href="ThreadArgs.html"> 6.5. Thread Arguments and Return Values</a>
|
|||
|
|
<a class="dropdown-item" href="ImplicitThreads.html"> 6.6. Implicit Threading and Language-based Threads</a>
|
|||
|
|
<a class="dropdown-item" href="Extended6Input.html"> 6.7. Extended Example: Keyboard Input Listener</a>
|
|||
|
|
<a class="dropdown-item" href="Extended6Primes.html"> 6.8. Extended Example: Concurrent Prime Number Search</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 7</b></a>
|
|||
|
|
<a class="dropdown-item" href="SynchOverview.html"> 7.1. Synchronization Primitives</a>
|
|||
|
|
<a class="dropdown-item" href="CritSect.html"> 7.2. Critical Sections and Peterson's Solution</a>
|
|||
|
|
<a class="dropdown-item" href="Locks.html"> 7.3. Locks</a>
|
|||
|
|
<a class="dropdown-item" href="Semaphores.html"> 7.4. Semaphores</a>
|
|||
|
|
<a class="dropdown-item" href="Barriers.html"> 7.5. Barriers</a>
|
|||
|
|
<a class="dropdown-item" href="Condvars.html"> 7.6. Condition Variables</a>
|
|||
|
|
<a class="dropdown-item" href="Deadlock.html"> 7.7. Deadlock</a>
|
|||
|
|
<a class="dropdown-item" href="Extended7Events.html"> 7.8. Extended Example: Event Log File</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 8</b></a>
|
|||
|
|
<a class="dropdown-item" href="SynchProblemsOverview.html"> 8.1. Synchronization Patterns and Problems</a>
|
|||
|
|
<a class="dropdown-item" href="SynchDesign.html"> 8.2. Basic Synchronization Design Patterns</a>
|
|||
|
|
<a class="dropdown-item" href="ProdCons.html"> 8.3. Producer-Consumer Problem</a>
|
|||
|
|
<a class="dropdown-item" href="ReadWrite.html"> 8.4. Readers-Writers Problem</a>
|
|||
|
|
<a class="dropdown-item" href="DiningPhil.html"> 8.5. Dining Philosophers Problem and Deadlock</a>
|
|||
|
|
<a class="dropdown-item" href="CigSmokers.html"> 8.6. Cigarette Smokers Problem and the Limits of Semaphores and Locks</a>
|
|||
|
|
<a class="dropdown-item" href="Extended8ModExp.html"> 8.7. Extended Example: Parallel Modular Exponentiation</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Chapter 9</b></a>
|
|||
|
|
<a class="dropdown-item" href="ParallelDistributedOverview.html"> 9.1. Parallel and Distributed Systems</a>
|
|||
|
|
<a class="dropdown-item" href="ParVConc.html"> 9.2. Parallelism vs. Concurrency</a>
|
|||
|
|
<a class="dropdown-item" href="ParallelDesign.html"> 9.3. Parallel Design Patterns</a>
|
|||
|
|
<a class="dropdown-item" href="Scaling.html"> 9.4. Limits of Parallelism and Scaling</a>
|
|||
|
|
<a class="dropdown-item" href="DistTiming.html"> 9.5. Timing in Distributed Environments</a>
|
|||
|
|
<a class="dropdown-item" href="DistDataStorage.html"> 9.6. Reliable Data Storage and Location</a>
|
|||
|
|
<a class="dropdown-item" href="DistConsensus.html"> 9.7. Consensus in Distributed Systems</a>
|
|||
|
|
<a class="dropdown-item" href="Extended9Blockchain.html"> 9.8. Extended Example: Blockchain Proof-of-Work</a>
|
|||
|
|
<div class="dropdown-divider"></div>
|
|||
|
|
<a class="dropdown-item disabled"><b>Appendix A</b></a>
|
|||
|
|
<a class="dropdown-item" href="CLangOverview.html"> A.1. C Language Reintroduction</a>
|
|||
|
|
<a class="dropdown-item" href="Debugging.html"> A.2. Documentation and Debugging</a>
|
|||
|
|
<a class="dropdown-item" href="BasicTypes.html"> A.3. Basic Types and Pointers</a>
|
|||
|
|
<a class="dropdown-item" href="Arrays.html"> A.4. Arrays, Structs, Enums, and Type Definitions</a>
|
|||
|
|
<a class="dropdown-item" href="Functions.html"> A.5. Functions and Scope</a>
|
|||
|
|
<a class="dropdown-item" href="Pointers.html"> A.6. Pointers and Dynamic Allocation</a>
|
|||
|
|
<a class="dropdown-item" href="Strings.html"> A.7. Strings</a>
|
|||
|
|
<a class="dropdown-item" href="FunctionPointers.html"> A.8. Function Pointers</a>
|
|||
|
|
<a class="dropdown-item" href="Files.html"> A.9. Files</a>
|
|||
|
|
</div>
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<ul class="navbar-nav flex-row ml-md-auto d-none d-md-flex">
|
|||
|
|
<li class="nav-item"><a class="nav-link jmu-gold" href="https://w3.cs.jmu.edu/kirkpams/OpenCSF/Books/csf/source/Wireless.rst"
|
|||
|
|
target="_blank" rel="nofollow">Show Source</a></li>
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</nav>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="container center">
|
|||
|
|
«  <a id="prevmod" href="LinkLayer.html">5.6. Link Layer</a>
|
|||
|
|
  ::  
|
|||
|
|
<a class="uplink" href="index.html">Contents</a>
|
|||
|
|
  ::  
|
|||
|
|
<a id="nextmod" href="Extended5DNS.html">5.8. Extended Example: DNS Client</a>  »
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
<br />
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="_static/js/jquery-2.1.4.min.js"></script>
|
|||
|
|
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
|
|||
|
|
<script type="text/javascript" src="_static/js/jquery-1.11.4-ui.min.js"></script>
|
|||
|
|
<script type="text/javascript" src="_static/js/forge-0.7.0.min.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../JSAV/lib/jquery.transit.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../JSAV/lib/raphael.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../JSAV/build/JSAV-min.js"></script>
|
|||
|
|
<script type="text/javascript" src="_static/js/config.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../lib/odsaUtils-min.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../lib/odsaMOD-min.js"></script>
|
|||
|
|
<script type="text/javascript" src="_static/js/d3-4.13.0.min.js"></script>
|
|||
|
|
<script type="text/javascript" src="_static/js/d3-selection-multi.v1.min.js"></script>
|
|||
|
|
<script type="text/javascript" src="../../../lib/dataStructures.js"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="container">
|
|||
|
|
|
|||
|
|
<script>ODSA.SETTINGS.DISP_MOD_COMP = true;ODSA.SETTINGS.MODULE_NAME = "Wireless";ODSA.SETTINGS.MODULE_LONG_NAME = "Wireless Connectivity: Wi-Fi, Bluetooth, and Zigbee";ODSA.SETTINGS.MODULE_CHAPTER = "The Internet and Connectivity"; ODSA.SETTINGS.BUILD_DATE = "2021-06-01 15:31:50"; ODSA.SETTINGS.BUILD_CMAP = false;JSAV_OPTIONS['lang']='en';JSAV_EXERCISE_OPTIONS['code']='java';</script><div class="section" id="wireless-connectivity-wi-fi-bluetooth-and-zigbee">
|
|||
|
|
<h1>5.7. Wireless Connectivity: Wi-Fi, Bluetooth, and Zigbee<a class="headerlink" href="Wireless.html#wireless-connectivity-wi-fi-bluetooth-and-zigbee" title="Permalink to this headline">¶</a></h1>
|
|||
|
|
<p>We close our survey of network technologies with a brief overview of three forms of wireless
|
|||
|
|
connectivity that facilitate three very different capabilities. <a class="reference internal" href="Glossary.html#term-wi-fi"><span class="xref std std-term">Wi-Fi</span></a> is the common name for
|
|||
|
|
the set of wireless technologies defined by the <a class="reference internal" href="Glossary.html#term-ieee-802-11"><span class="xref std std-term">IEEE 802.11</span></a> working groups and supported by
|
|||
|
|
the <a class="reference internal" href="Glossary.html#term-wi-fi-alliance"><span class="xref std std-term">Wi-Fi Alliance</span></a>. <em>Bluetooth</em> is a set of standards defined by the <a class="reference internal" href="Glossary.html#term-bluetooth-special-interest-group"><span class="xref std std-term">Bluetooth SIG</span></a>. <a class="reference internal" href="Glossary.html#term-zigbee"><span class="xref std std-term">Zigbee</span></a> is a suite of protocols maintained by the
|
|||
|
|
<a class="reference internal" href="Glossary.html#term-zigbee-alliance"><span class="xref std std-term">Zigbee Alliance</span></a>, intended to create short-range networks using radio communication defined
|
|||
|
|
by the <a class="reference internal" href="Glossary.html#term-ieee-802-15-4"><span class="xref std std-term">IEEE 802.15.4</span></a> working group.</p>
|
|||
|
|
<div class="section" id="wireless-protocol-stacks-and-uses">
|
|||
|
|
<h2>5.7.1. Wireless Protocol Stacks and Uses<a class="headerlink" href="Wireless.html#wireless-protocol-stacks-and-uses" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Wi-Fi is designed to act as a substitute for the wired connections that make up the traditional link
|
|||
|
|
and physical layers. That is, Wi-Fi assumes that the goal is to use a wireless connection to
|
|||
|
|
facilitate Internet access for a mobile device. As such, devices like laptops and tablets use the
|
|||
|
|
802.11 technology standards to communicate with an <a class="reference internal" href="Glossary.html#term-access-point"><span class="xref std std-term">access point</span></a> that is connected to an ISP.
|
|||
|
|
Readers may be familiar with the different standards, such as 802.11a, 802.11g, and 802.11n. These
|
|||
|
|
standards offer different levels of performance by specifying different features of the radio that
|
|||
|
|
is used. For instance, 802.11n wireless routers can have more than one antenna to support
|
|||
|
|
<a class="reference internal" href="Glossary.html#term-multiple-input-and-multiple-output"><span class="xref std std-term">multiple input and multiple output</span></a> (MIMO) access; with MIMO, the router can be sending and
|
|||
|
|
receiving communications with several devices all at one, increasing the efficiency of the overall
|
|||
|
|
system. Early standards did not assume MIMO-compatible radios, so the maximum speed and throughput
|
|||
|
|
were significantly lower.</p>
|
|||
|
|
<p>In contrast, Bluetooth was not designed to connect a device to the Internet. Instead, Bluetooth
|
|||
|
|
devices focus on short-range <a class="reference internal" href="Glossary.html#term-mobile-ad-hoc-network"><span class="xref std std-term">mobile ad hoc networks (MANETs)</span></a>. In a MANET, unknown devices
|
|||
|
|
establish connections with efficient, minimal overhead and configuration; the goal is to allow a new
|
|||
|
|
device to join the network rapidly, exchange some data, then disconnect. In the simplest case,
|
|||
|
|
Bluetooth speakers or headphones may be used to play the sound that would otherwise be produced by a
|
|||
|
|
computer’s speakers; similarly, a Bluetooth keyboard or mouse reduce the number of cables that must
|
|||
|
|
physically connect a computer and its peripheral devices. Bluetooth devices are generally assumed to
|
|||
|
|
have low-power requirements, so the range of the connection can be as short as 1 to 10 meters.</p>
|
|||
|
|
<div class="figure mb-2 align-right" id="id1" style="width: 35%">
|
|||
|
|
<span id="wirelessbluetooth"></span><a class="reference internal image-reference" href="_images/CSF-Images.5.13.png"><img class="p-3 mb-2 align-center border border-dark rounded-lg" alt="The Bluetooth protocol stack does not assume Internet access" src="_images/CSF-Images.5.13.png" style="width: 95%;" /></a>
|
|||
|
|
<p class="caption align-center px-3"><span class="caption-text"> Figure 5.7.1: The Bluetooth protocol stack does not assume Internet access</span></p>
|
|||
|
|
</div>
|
|||
|
|
<p>Since Bluetooth is not intended to provide Internet access, its protocol stack is very different
|
|||
|
|
than the 5-layer model we have examined previously. <a href="Wireless.html#wirelessbluetooth">Figure 5.7.1</a> shows
|
|||
|
|
the main structure of the Bluetooth protocol stack. At the lowest layer, the baseband and
|
|||
|
|
the link manager/link controller (LM/LC) layers provide the basic point-to-point modulation
|
|||
|
|
of the radio signal. The logical link control and adaptation protocol (L2CAP) acts in a
|
|||
|
|
manner similar to the traditional link layer by multiplexing access to the radio for higher-layer
|
|||
|
|
protocols. Given Bluetooth’s usage model is for point-to-point communication, its protocol stack
|
|||
|
|
does not offer an equivalent of the Internet layer.</p>
|
|||
|
|
<p>Bluetooth defines a number of protocols that are analogous to a transport layer. The RFCOMM
|
|||
|
|
protocol provides a generic serial port interface, similar to a TCP stream socket.
|
|||
|
|
Multichannel adaptation protocol (MCAP) defines a common transport layer for medical
|
|||
|
|
devices. Lastly, the generic access profile (GAP) creates an extendible interface that can
|
|||
|
|
be used for future applications that are not defined in the specification.</p>
|
|||
|
|
<p><a class="reference internal" href="Glossary.html#term-bluetooth-profile"><span class="xref std std-term">Bluetooth profiles</span></a> serve as the equivalent of the application layer. The
|
|||
|
|
hands-free protocol (HFP) defines the interface for connecting a cell-phone to a wireless
|
|||
|
|
peripheral, such as a headset or an automobile. HFP and object exchange (OBEX)—a generic profile for
|
|||
|
|
exchanging binary data—run on top of the RFCOMM protocol. The health device protocol (HDP) provides
|
|||
|
|
a common interface for healthcare devices, such as thermometers or heart meters, running on the MCAP
|
|||
|
|
protocol. Some profiles, such as human interface device (HID) and audio/video distribution transport
|
|||
|
|
protocol (AVDTP), run directly on top of L2CAP to minimize their latency to support real-time human
|
|||
|
|
interactions. HID is used for wireless devices such as a mouse and keyboard, whereas AVDTP is used
|
|||
|
|
for devices like headphones. More recently, the advanced audio distribution profile (A2DP) has been
|
|||
|
|
added on top of AVDTP to provide improved service for audio-visual devices.</p>
|
|||
|
|
<p>The Bluetooth SIG was established with a core set of applications in mind. The designers also had a
|
|||
|
|
stated design goal to use existing radios, rather than designing new technology from scratch. These
|
|||
|
|
design goals allowed the Bluetooth SIG to get devices on the market for consumer use very rapidly.
|
|||
|
|
By working within the constraints of the top and bottom layers (the applications and the existing
|
|||
|
|
radios), the designers were able to construct a working protocol stack in a short period of time.</p>
|
|||
|
|
<p>The Zigbee wireless standard lies somewhere in between the goals of Wi-Fi and Bluetooth. Like
|
|||
|
|
Bluetooth, Zigbee is used for MANETs, but on a larger and more complex scale. To be specific,
|
|||
|
|
Bluetooth is generally based on a <a class="reference internal" href="Glossary.html#term-star-topology"><span class="xref std std-term">star topology</span></a>, with multiple peripherals (keyboard, mouse,
|
|||
|
|
speakers) connecting to a central device (laptop); no one expects their keyboard and mouse to be
|
|||
|
|
exchanging data packets. In contrast, Zigbee provides support for <a class="reference internal" href="Glossary.html#term-wireless-mesh-network"><span class="xref std std-term">wireless mesh networks</span></a>, in
|
|||
|
|
which devices provide support for routing packets if two hosts are too far apart to communicate
|
|||
|
|
directly. Note that the Internet backbone can be described as a wired mesh network, allowing
|
|||
|
|
multiple routing paths; Zigbee takes this idea and replaces the wired connections with wireless
|
|||
|
|
ones. Zigbee uses this structure to support applications like low-powered sensor networks. Zigbee is
|
|||
|
|
one of the protocols used to support the <a class="reference internal" href="Glossary.html#term-internet-of-things"><span class="xref std std-term">Internet of Things</span></a> (IoT). IoT is the general
|
|||
|
|
concept of connecting non-traditional computing devices, such as home appliances, thermostats, or
|
|||
|
|
entertainment devices, to each other and to the Internet as a whole.</p>
|
|||
|
|
<div class="figure mb-2 align-right" id="id2" style="width: 40%">
|
|||
|
|
<span id="wirelesszigbee"></span><a class="reference internal image-reference" href="_images/CSF-Images.5.14.png"><img class="p-3 mb-2 align-center border border-dark rounded-lg" alt="The Zigbee protocol stack supports custom short-range networks" src="_images/CSF-Images.5.14.png" style="width: 95%;" /></a>
|
|||
|
|
<p class="caption align-center px-3"><span class="caption-text"> Figure 5.7.2: The Zigbee protocol stack supports custom short-range networks</span></p>
|
|||
|
|
</div>
|
|||
|
|
<p><a href="Wireless.html#wirelesszigbee">Figure 5.7.2</a> shows the structure of the Zigbee protocol stack. The lowest
|
|||
|
|
layers, MAC and PHY, are defined by the 802.15.4 working group, independent of Zigbee itself. These
|
|||
|
|
layers define a generic point-to-point communication that can be used with low-power radios. Zigbee
|
|||
|
|
refers specifically to the layers built on top of this this foundation. The NWK layer coordinates
|
|||
|
|
the mesh routing that builds the network. The APS and Zigbee Device Object (ZDO) Management provide
|
|||
|
|
common services that applications can use, such as cryptographic key management and information
|
|||
|
|
about devices on the network. Applications can access ZDOs through an interface at the application
|
|||
|
|
layer, or they can request services through application end points.</p>
|
|||
|
|
<p>These three protocol stacks serve illustrate how wireless connectivity can be used to provide very
|
|||
|
|
different services. Wi-Fi is designed to extend the traditional Internet model to mobile devices,
|
|||
|
|
replacing the last link of the network with a wireless access point. Bluetooth defines a local
|
|||
|
|
point-to-point mechanism that allows computer peripherals to communicate without a cable physically
|
|||
|
|
connecting the devices. Zigbee creates a wireless mesh network that can be used to route data, such
|
|||
|
|
as sensor readings, between low-powered devices. Zigbee devices can also have additional components
|
|||
|
|
added that allow them to link to an Internet access point, connecting the sensor network and the
|
|||
|
|
Internet. These separate infrastructures provide support for application designers to build services
|
|||
|
|
that can communicate without physical connections.</p>
|
|||
|
|
<div
|
|||
|
|
id="InterWirelessSumm"
|
|||
|
|
class="embedContainer"
|
|||
|
|
data-exer-name="InterWirelessSumm"
|
|||
|
|
data-long-name="Wireless connectivity questions"
|
|||
|
|
data-short-name="InterWirelessSumm"
|
|||
|
|
data-frame-src="../../../Exercises/Internet/InterWirelessSumm.html?selfLoggingEnabled=false&localMode=true&module=Wireless"
|
|||
|
|
data-frame-width="950"
|
|||
|
|
data-frame-height="775"
|
|||
|
|
data-external="false"
|
|||
|
|
data-points="0"
|
|||
|
|
data-required="False"
|
|||
|
|
data-showhide="show"
|
|||
|
|
data-threshold="3"
|
|||
|
|
data-type="ka"
|
|||
|
|
data-exer-id="">
|
|||
|
|
|
|||
|
|
<div class="center">
|
|||
|
|
<div id="InterWirelessSumm_iframe"></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="container">
|
|||
|
|
|
|||
|
|
<div class="mt-4 container center">
|
|||
|
|
«  <a id="prevmod1" href="LinkLayer.html">5.6. Link Layer</a>
|
|||
|
|
  ::  
|
|||
|
|
<a class="uplink" href="index.html">Contents</a>
|
|||
|
|
  ::  
|
|||
|
|
<a id="nextmod1" href="Extended5DNS.html">5.8. Extended Example: DNS Client</a>  »
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<br />
|
|||
|
|
|
|||
|
|
<div class="row jmu-dark-purple-bg">
|
|||
|
|
<div class="col-md-12">
|
|||
|
|
<center>
|
|||
|
|
<a id="contact_us" class="btn button-link-no-blue jmu-gold" rel="nofollow" href="mailto:webmaster@opencsf.org" role="button">Contact Us</a>
|
|||
|
|
<a id="license" class="btn button-link-no-blue jmu-gold" rel="nofollow" href="https://w3.cs.jmu.edu/kirkpams/OpenCSF/lib/license.html" target="_blank">License</a>
|
|||
|
|
</center>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script src="_static/js/popper.js-1.14.7-min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
|
|||
|
|
<script src="_static/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
|
|||
|
|
</body>
|
|||
|
|
</html>
|