smart home technologies networking. networking for smart homes requirements network topologies...
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Smart Home Technologies
Networking
Networking for Smart Homes Requirements Network Topologies Technologies
Networking Service Discovery
Requirements Noise Rejection
Network has to allow for reliable communication Requires preservation of data and synchronization of
data lines Bandwidth
Smart Homes can contain many sensors and actuators Sensor data can be generated at different rates
Connectivity Sensors have to be connected to processing units
Integration Network structures have to be integrated into
buildings Privacy and Security
Smart Home networks will transfer private and sensitive data
Bandwidth Requirements Example
Camera (15) – 320x240, 8-bit color Motion (15) – distance, direction, velocity Temperature (12) Humidity (12) Light (12) – frequency, intensity Microphone (12) – 8000 Hz Gas (4) Pressure (100)
Bandwidth RequirementsSensor Number Bits/sec (1) Bits/sec (total)
Camera (320x240) 8-bit color
15 184,320 2,764,800
Motion (dir/dis/vel)
15 48 720
Temperature 12 16 192
Humidity 12 16 192
Light (inten/freq) 12 32 384
Microphone (8KHz)
12 64,000 768,000
Gas 4 16 64
Pressure 100 16 1600
Total 182 248,464 3,535,952
Other Bandwidth Requirements Audio
Phones (16 kHz, 8 bit) Radios (44 kHz, 16 bit) TVs (44 kHz, 16 bit) Media players (44 kHz,
16 bit) Monitoring (16 kHz, 8
bit) 2.4 Mbits/sec (one
each)
Internet, control, …
Video Phones (30fps,
320x240, 8-bit color) TVs (60 fps, 1024x768,
24-bit color) Video players (60 fps,
1024x768, 24-bit color) Monitoring (30 fps,
320x240, 8-bit color) ~6.9 Gbits/sec (one
each)
Other Bandwidth Requirements
Other Network Requirements Worst-case throughput: 10
Gbits/sec Maximum throughput: 5 Gbits/sec Quality of Service (QoS)
Audio, video Plug and play (service discovery)
Network Topologies Infrastructure-Based Networks
Pre-defined routes through the network Nodes can directly address each other and routers
forward packets appropriately Addition of nodes changes the routing pattern
Point-To-Point Networks Every node has a connection to every other node Communication is directly between the nodes High overhead setting up the connections for new nodes
Ad-Hoc Networks Routes are determined “on the fly” and can change Nodes forward signals for other nodes Addition of nodes can be handled relatively
straightforwardly
Topologies (Point-to-Point) Every device is connected to
every other device Good points
simplest approach no addressing needed everyone is your neighbor you can always talk to your neighbor
Bad points number of ports/lines grow relatively
quickly with the number of devices
A B
C D
Topologies (Hierarchy) Devices are connected via hubs to
other devices If everyone is connected to a single hub,
it is called a Star topology Good points
fewer connections devices can have neighborhoods
Bad points you need an address you may have to wait to talk to a
neighbor asymmetric communication with some
devices
A
B
C
D
Topologies (Broadcast) All of the devices are connected to
a single wire Good points
single wire everyone is your neighbor
Bad points you need an address you may have to wait to talk to anyone collisions can occur communication times become
statistical
A
B
C
D
Physical Addresses If more than two devices are on the same wire
(bus), you will need an address to send and receive data
Approaches separate vs. combined data/address lines hardwired vs. selectable address
Issues as the number of devices increase, the address
space (size of the address) must increase hardwired addresses may tell you nothing about
the network topology addresses will be used up by devices that might
not be on-line so your address space may be too big, causing too
much overhead
A
B
C
D
0001
1111
1000
1100
Virtual Addresses A solution to some physical address
problems is a virtual address the address space (size of the address) can be
reduced by only giving addresses to on-line devices
addresses can be set up to support network topology
Approaches fixed vs. run-time addresses universal vs. p-to-p addresses
Issues how to assign them their relationship to the physical address
A
B
C
D
00
01
10
11
Network Technologies
Wired Phone Line Power Line New Wire
Wireless RF Infrared
Wired Network Technology Examples Phone line
Home Phoneline Networking Alliance (HomePNA) Power line
X10 Consumer Electronics Bus (CEBus) HomePlug LonWorks
New wire Ethernet (coax, twisted pair, optical fiber) Universal Serial Bus (USB) IEEE 1394 Firewire
Home Audio Video Interoperability (HAVi) Specialty: audio, video
Phoneline Networking Home Phoneline Networking Alliance
(HomePNA) www.homepna.org
IEEE 802.3 (Ethernet) Carrier Sense Multiple Access with Collision
Detect (CSMA/CD) 10 Mbps (HPNA 2.0) Length: 500 feet
HomePNA Packet
HomePNA Frequencies Standard voice (POTS): 20Hz - 3.4kHz UADSL: 25kHz - 1.1MHz Home network: 5.5MHz - 9.5MHz
Phoneline Network Issues Random wiring topologies & signal
attenuation Home phoneline wiring system is a random
“tree” topology Simply plugging in the phone or
disconnecting the fax changes the tree This topology can cause signal attenuation
Signal noise Appliances, heaters, air conditioners,
consumer appliances & telephones can introduce signal noise onto the phone wires
Powerline Networking Ubiquity of power lines 10+ Mbps Technologies
X10 Consumer Electronics Bus (CEBus) HomePlug LonWorks
X10 X10 controllers send signals over
existing AC wiring to receiver modules
X10 technology transmits binary data using the Amplitude Modulation (AM) technique
www.x10.com
X10 To differentiate the data symbols, the
carrier uses the zero-voltage crossing point of the 60Hz AC sine wave on the cycle’s positive or negative transition
Synchronized receivers accept the carrier at each zero-crossing point
X10 uses two zero crossings to transmit a binary digit so as to reduce errors
X10 Every bit requires a full 60 Hertz cycle
and thus the X10 transmission rate is limited to only 60 bps
Usually a complete X10 command consists of two packets with a 3 cycle gap between each packet Each packet contains two identical
messages of 11 bits (or 11 cycles) each A complete X-10 command consumes 47
cycles that yields a transmission time of about 0.8s
Consumer Electronics Bus (CEBus) Open standard providing separate physical
layer specification for communication on power lines and other media Electronic Industries Association (EIA-600) www.cebus.org
Data packets are transmitted by the transceiver at about 10 Kbps
Carrier Sense Multiple Access/Collision Detect (CSMA/CD)
Employing spread spectrum technology (100Hz-400 Hz)
OSI and CEBus (EIA-600)
Spread Spectrum Modulation Frequency spectrum of a data-signal is
spread using a code uncorrelated with that signal
Sacrifices bandwidth to gain signal-to-noise performance
HomePlug HomePlug Powerline Alliance
www.homeplug.org Spread-spectrum technology
HomePlug Speed
Support file transfers at 10BaseT-like rates Either node-to-node file transfer or
scenarios with multiple nodes performing simultaneous file transfers
HomePlug 1.0 (14 Mbps) Voice over IP (VoIP)
Maintain adequate QoS while supporting multiple, simultaneous VoIP calls while other nodes are transferring files and during multiple media streams
HomePlug Interoperability
Interoperate with other networking technologies Co-exist with existing powerline networking
technologies such as X-10, CEBus and LonWorks
Security Contain strong privacy features Support multiple logical networks on a single
physical medium Be applicable to markets in North America,
Europe and Asia
LonWorks Local Operation Networks (LonWorks) Developed by Echelon Corporation
www.echelon.com Provides a peer-to-peer communication
protocol, implementing Carrier Sense Multiple Access (CSMA) techniques
1.25 Mbps Works for other wired and wireless media
LonWorks A common message-based
communications protocol LonTalk protocol implements all
seven layers of the OSI model using a mixture of hardware and firmware on a silicon chip
Protocol can be run as fast as 20 MHz
Powerline Network Issues Noise
Switching power supplies Wound motors
Vacuum cleaners, kitchen appliances, drills
Dimmers Security Signal attenuation
New Wire Networking Ethernet (coax, twisted pair, optical
fiber) Universal Serial Bus (USB) IEEE 1394 Firewire
Home Audio Video Interoperability (HAVi) Specialty: audio, video
Ethernet IEEE 802.3
CSMA/CD Up to 1 Gbps
IEEE 802.3ae 10GBase-X, 10 Gps Lengths up to 40 km
www.ethermanage.com/ethernet
IEEE 802.3
Universal Serial Bus (USB) www.usb.org 480 Mbps Plug and Play Hot pluggable Up to 127 devices simultaneously Powered bus 5m maximum cable length
IEEE 1394 Firewire (i.LINK) Digital interface
No need to convert digital data into analog and tolerate a loss of data integrity
Transferring data @ 100, 200, 400 Mbps
Physically small The thin serial cable can replace larger
and more expensive interfaces
IEEE 1394 Firewire No need for terminators or device
IDs Hot pluggable
Users can add or remove 1394 devices with the bus active
Scaleable architecture May mix 100, 200, and 400 Mbps
devices on a bus
IEEE 1394 Firewire It can connect up to 63 devices @
transfer rate of 400Mbps Up to 16 nodes can be daisy-
chained through the connectors Standard cables up to 4.5 m in length
for a total standard cable length of 72 m
IEEE 1394 Firewire Flexible topology
Support of daisy chaining and branching for true peer-to-peer communication
Non-proprietary
IEEE 1394b 1394b is a significant enhancement to
the basic 1394 specification that enables: Speed increases to 3.2 Gbps Distances of 100 meters on UTP-5, plastic
optical fiber and glass optical fiber Significantly reduces latency times by using
arbitration Fully backwards compatible with the
current 1394 and 1394a specifications
I2C (Inter-Integrated Circuit)
One of the oldest controller buses Philips (1980s)
Low-cost chip-to-chip communication link uses two wires to form a clocked serial bus
one called Clock (SCL) and the other Data (SDA) the SDA carries address, selection, control,
and data Overview
multi-master bus (up to 1024 devices) can run at speed up to 3.4 Mbps can be used as a SAN
but normal ranges are on the order of 14 cm
Home Audio Video Interoperability (HAVi) HAVi is a digital Audio Video
networking initiative that provides a home networking software specification Seamless interoperability among
home entertainment products Designed to meet the particular
demands of digital audio and video www.havi.org
HAVi Defines operating-system-neutral
middleware that manages: Multi-directional AV streams Event schedule Registries
Takes advantage of chips built into modern audio and video appliances Provides the management function of a
dedicated audio-video networking system IEEE 1394 (i. LINK or FireWire) has been
chosen as the interconnection medium
Specialty Wiring Audio
Coax RCA Speaker wire
Video Coax RCA VGA
~100m maximum cable lengths
Automotive Inspired Busses
LIN (Local Interconnect Network) Designed for European cars (still
used) Very simple
single wire single mastered bus
Overview 1 master, up to 16 Slaves uses a message-based protocol maximum distance of 40 m Two data rates
9,600 and 19.2 Kbps
CAN(Controller Area Network )
CAN was designed to support emission control system in European cars
but became a general automation control bus Capable of
high-speed (1 Mbits/s) data transmission over short distances (40 m)
low-speed (5 kbits/s) transmissions at lengths of up to 10,000 m
Overview a multi-master bus highly fault tolerant
Built-in support for error detection and handling
MOST(Media Oriented System Transport)
An inexpensive automotive and appliance network 25 Mbps fiber-
optic bus for real-time data
transfer used in surround-
sound systems and CD and DVD players
FlexRay Designed to replace LIN, CAN and MOST
as a ‘by wire’ solution for future cars It is a fiber-optic bus (like MOST) Current speed
10 Mbps But it is designed to go much higher
could run faster than 100 Mbps But remember
that is faster than most current micro-controller’s internal bus speed
Wireless Network Technologies
Digital Enhanced Cordless Telecommunications (DECT)
HomeRF Bluetooth IEEE 802.11 HiperLAN2 Infrared
General Wireless
Narrow band Spread spectrum
Direct Sequence (DSSS) Frequency Hopping (FHSS)
Orthogonal Frequency Division Multiplexing (OFDM)
DECT Digital Enhanced Cordless
Telecommunications (DECT) www.dectweb.com Digital radio technology Dynamic channel selection Encryption, authentication, identification 500 Kbps – 2 Mbps Cordless phones
HomeRF www.homerf.org Shared Wireless Access Protocol
(SWAP) IEEE 802.11 for data DECT for voice
HomeRF Specifications
2.4 GHz band FHSS 1.6 Mbps (10 Mbps with SWAP 2.0) 50m range 127 nodes
Bluetooth www.bluetooth.com Ericsson, the principal inventor,
borrowed the name from Harald Bluetooth (son of Gorm) The King of Denmark circa 900AD United Denmark and Norway
Bluetooth Specifications
2.4 GHz FHSS (79 channels)
1600 hops per second Error correction
1 Mbps capacity, 780 Kbps throughput 10m distance Low power (1 mW)
Bluetooth Personal Area Networks (PANs) Piconet
Collection of up to 8 devices using same hopping sequence
Scatternet Collection of piconets, each with
different hopping sequence
IEEE 802.11
Standard Frequency
PHY Layer
Data Rate
Distance*
802.11a 5 GHz OFDM 54 Mbps 50m
802.11b 2.4 GHz DSSS 11 Mbps 100m
802.11e,MAC layer
Offers QoS and backwards compatibility(in committee)
802.11g 2.4 GHz OFDM 54 Mbps ?
* Data rate degrades with distance.
HiperLAN2 www.hiperlan2.com 5 GHz 54 Mbps OFDM Automatic frequency allocation TDMA/TDD (Time Division) QoS support
Infrared www.irda.org Directed – line of sight
1m range Diffuse – reflective
Limited to room size Speed
4 Mbps available 16 Mbps coming 50 Mbps possible
Wireless Networking
Wireless Issues Distance 2.4 GHz interference
Microwave ovens Cordless phones
Security Not a backbone solution
Wireless Personal Area Networks (WPAN) 802.15.X
Intended for low cost, low distance, low power personal networks
Often intended for mesh networking E.g. ZigBee (build on 802.11.4)
Ad-Hoc Mesh Networks Ad-Hoc networks of wireless sensors
and devices Benefits:
Easy to build (require no infrastructure to be available)
Dynamic and mobile Fault tolerant (usually no single point of failure)
Challenges: Choice of routing to optimize performance
QoS Power consumption
Synchronization and collision avoidance
Service Discovery Self-configuring devices Device becomes aware of network,
network services and other devices Automatic, as opposed to manual
(e.g., DHCP, DNS, LDAP) Several incompatible protocols
Service Discovery Protocols Salutation Service Location Protocol (SLP) Jini Universal Plug and Play Zero-Configuration Networking
Salutation www.salutation.org Architecture for looking up,
discovering and accessing services and information
Salutation Abstractions for devices, applications,
and services Current definitions
Printers Fax machines Document storage devices Address book Schedule Voice message answer, send, storage More coming (e.g., display, OS)
Salutation Capabilities exchange protocol Service request protocol “Personalities” (standardized
protocols for common services) APIs for information access and
session management
Service Location Protocol (SLP)
Developed by Internet Engineering Task Force (IETF)
Applies existing Internet standards to service discovery problem
www.srvloc.org www.openslp.org
SLP Agents User Agent (UA)
The SLP User Agent is a software entity that is looking for the location of one or more services.
Service Agent (SA) The SLP Service Agent is a software entity that
provides the location of one or more services. Directory Agent(DA)
The SLP Directory Agent is a software entity that acts as a centralized repository for service location information.
SLP Messages Service Request (SrvRqst)
Message sent by UAs to SAs and DAs to request the location of a service.
Service Reply (SrvRply) Message sent by SAs and DAs in reply
to a SrvRqst. The SrvRply contains the URL of the requested service.
SLP Messages (cont.) Service Registration (SrvReg)
Message sent by SAs to DAs containing information about a service that is available.
Service Deregister (SrvDeReg) Message sent by SAs to inform DAs that a
service is no longer available. Service Acknowledge (SrvAck)
A generic acknowledgment that is sent by DAs to SAs as a reply to SrvReg and SrcDeReg messages.
SLP Messages (cont.) Attribute Request (AttrRqst)
Message sent by UAs to request the attributes of a service.
Attribute Reply (AttrRply) Message sent by SAs and DAs in reply
to a AttrRqst. The AttrRply contains the list of attributes that were requested.
SLP Messages (cont.) Service Type Request (SrvTypeRqst)
Message sent by UAs to SAs and DAs requesting the types of services that are available.
Service Type Reply (SrvTypeRply) Message by SAs and DAs in reply to a
SrvTypeRqst. The SrvTypeRply contains a list of requested service types.
SLP Messages (cont.) DA Advertisement (DAAdvert)
Message sent by DAs to let SAs and UAs know where they are.
SA Advertisement (SAAdvert) Message sent by SAs to let UAs know
where they are.
Unicast or multicast messaging
Jini Service discovery for networks of
Java-enabled devices www.sun.com/jini www.jini.org
Jini
Jini Services Lookup Communications
Java-RMI, CORBA, … Security Leasing Events
Universal Plug and Play Microsoft’s service discovery
approach IP-based discovery protocols
XML www.upnp.org Examples
Universal Plug and Play Devices
Containers for services XML description
Services Actions (i.e., methods)
Control server Event server
State (i.e., variables) XML description
Universal Plug and Play Control points
Retrieve the device description and get a list of associated services.
Retrieve service descriptions for interesting services.
Invoke actions to control the service. Subscribe to the service’s event source.
Anytime the state of the service changes, the event server will send an event to the control point.
UPnP Protocols Protocols
UDP, TCP/IP, HTTP, XML Simple Service Discovery Protocol
(SSDP) Generic Event Notification Architecture
(GENA) Send/receive event notifications using
HTTP over TCP/IP and multicast UDP Simple Object Access Protocol (SOAP)
XML and HTTP for remote procedure calls
UPnP Protocol StackUPnP Vendor Defined
UPnP Forum Working Committee Defined
UPnP Device Architecture Defined
HTTPMU(Discovery)
HTTPU(Discovery)
SOAP(Control)
HTTP(Description)
UDP TCP
SSDP GENA SSDP
IP
HTTP
GENA(Events)
Zero-Configuration Networking Zeroconf (www.zeroconf.org) IETF standard Objectives
Allocate addresses without a DHCP server Translate between names and IP addresses
without a DNS server Find services, like printers, without a directory
server Allocate IP Multicast addresses without a
MADCAP server Multicast Address Dynamic Client Allocation Protocol
Zeroconf Protocols Address autoconfiguration
Configure interfaces with unique addresses
Determine which subnet mask to use Detect duplicate address assignment Cope with collisions
Name-to-address translation Multicast DNS Decentralized
Zeroconf Protocols Service discovery
Service Location Protocol (SLP) DNS Service Resource Record
Use expanded DNS for service requests Multicast address allocation
Zeroconf Multicast Address Allocation Protocol (ZMAAP)
Allocate unique addresses and maintain them over time
Prevent reallocation of assigned addresses Be notified of multicast allocation collision