Transcript 投影片 1

Chapter 4
MOBILE DEVICE CONNECTIVITY
IN HOME NETWORKS
Section 4.1
Related Work
4.1 Related Work
Two standardization forums: ->Decentralized home
network, targeted for home entertainment
applications
1.Home Audio Video interoperability (HAVi)
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Based on 1394
Quality of Service (QoS).
Non-IP networking
2.Digital Living Network Alliance (DLNA)
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Based on Universal-Plug-and-Play (UPnP)
Aims at creating interoperability guidelines based on existing standards.
4.1 Related Work
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Open Services Gateway Initiative (OSGi)->Centralized
A framework that provides API and Java execution
environment for building integrated home networks
and adaptation functions between UPnP-controlled
devices.
Section 4.2
Basic Home Use Cases
4.2 Basic Home Use Cases
本圖取自"Technologies for Home Networking". Edited by Sudhir Dixit and Ramjee Prasad, published by John Wiley, 2008.
4.2 Basic Home Use Cases
本圖取自"Technologies for Home Networking". Edited by Sudhir Dixit and Ramjee Prasad, published by John Wiley, 2008.
Section 4.3
Home Networking Challenges
4.3 Home Networking Challenges
Self-configuring
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Buy-plug-and-play; incremental network deployment
Intuitive user interface
2. Self-healing
Radio interference
Cross-talk
Uneven wireless coverage …etc
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Provide autoresume; easy-to-understand error explanation; easy-to-use debug tool
3. Security
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Wired Equivalent Privacy (WEP)
Wi-Fi Protected Access (WPA)
HTTP Secure (HTTPS)
Bluetooth Security
UPnP security ...etc
4.3 Home Networking Challenges
4. Remote Access: same experience as at home
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Round-trip delay ( GPRS vs. DSL vs. 802.11),
Cost ( Cellular vs. 802.11),
Capabilities of the devices (Desktop vs. Laptop vs. Mobile
phone).
5. Dynamic IP addresses.
6. Mobile devices connecting
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Users move in and out of range of local access points
Battery life
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Screen size
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Section 4.4
Architecture and Technologies for
Local and Remote Home
Connectinity
4.4.1 Overview of Home
Connectivity Architecture
Architecture : Centralized -> Decentralized
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Automatic configuration and ease-of-use features cannot rely on a
central element to hide technologies behind uniform APIs and
middleware.
Based on a layered approach.
 Lower level : TCP/IP
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Middle level: Control technologies ->UPnP , SLP
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High level: Applications and media formats ensure
interoperability and usability of the system.
4.4.2 Local Connectivity
本圖取自"Technologies for Home Networking". Edited by Sudhir Dixit and Ramjee Prasad, published by John Wiley, 2008.
4.4.2 Local Connectivity
Infrastructure-based :
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AP, switch, router, DHCP server
Connect : Fixed
Ad hoc (Peer-to-Peer) based:
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Connect : Opportunistic
Point-to-Point interactions between two devices
4.4.2 Local Connectivity
Link-level technologies:
802.3 (Ethernet 10/100/1000 Mbps):
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High data-rates, Low delays
Used for fixed home devices and mobile (No moving)
Requires cabling the home
802.11 a/b/g (Wi-Fi)
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Allows for mobility within the home
Seamless support for Ethernet and IP
Unlicensed spectrum -> Signal fluctuation
4.4.2 Local Connectivity
Bluetooth
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Short-range, Low data-rates
Support for Ethernet encapsulation with BENP
Mainly used in ad hoc mode
UltraWideBand (UWB; WiMedia)
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Emerging wireless technology
Short-range, High-speed communication
Availability of the Wireless USB specification
Main issue: Delay the wide deployment in home networks
due to lack of broad consensus in standardization
4.4.2 Local Connectivity
IEEE 802.15.4
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Low data-rates (hundreds of Kbps), conserving
power
Home automation applications involving sensors and
actuators
Suitable for connecting a large number of devices
HomePlug
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High data-rates ( Tens of Mbps)
Plugged in regular electrical power sockets
Suitable for transmission of multimedia content
4.4.2 Local Connectivity
IEEE 1394 (FireWire)
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Serial bus wireline technology
Synchronous mode that can guarantee bandwidth.
Suitable for connecting several devices at the same
time
Under pressure from USB 2.0
Near-Field Communications (NFC)
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Two-way communication between two devices
Suitable for IP traffic exchange
4.4.2 Local Connectivity
Mobile can use any of the above wireless or wireline
link-level bearers to connect locally.
Two problems to overcome:
 To reduce power and conserve energy
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To deal with frequent disconnections caused by
signal fluctuations, interference, user mobility.
4.4.3 Remote Connectivity
Three Challenges:
1. A broadband connection uses dynamic IP
addresses that in many cases are not even
public.
->Dynamic DNS
2. Traversing firewalls and NATs
3. Ensure the security of the remote connection
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VPN (Virtual Private Network)
4.4.3 Remote Connectivity
本圖取自"Technologies for Home Networking". Edited by Sudhir Dixit and Ramjee Prasad, published by John Wiley, 2008.
4.4.3 Remote Connectivity
Several ways to implement remote access:
1. Proxy solution
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Use distributed middleware (UPnP)
Authentication by TLS/ Secure Sockets Layer (SSL)
2. VPN-based solution
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Requires VPN gateway at the Internet gateway and
VPN client at the remote terminal