Smart Home Technologies
Networking
Networking for Smart Homes



Requirements
Network Topologies
Technologies


Networking
Service Discovery
Requirements

Noise Rejection



Bandwidth



Sensors have to be connected to processing units
Integration


Smart Homes can contain many sensors and actuators
Sensor data can be generated at different rates
Connectivity


Network has to allow for reliable communication
Requires preservation of data and synchronization of data
lines
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 Requirements
Sensor
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




Point-To-Point 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
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)

A
B

Every device is connected to every
other device
Good points

C
D




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
Topologies (Hierarchy)

A
B
Devices are connected via hubs to other
devices


Good points

C


fewer connections
devices can have neighborhoods
Bad points

D
If everyone is connected to a single hub, it
is called a Star topology


you need an address
you may have to wait to talk to a neighbor
asymmetric communication with some
devices
Topologies (Broadcast)

A

B
All of the devices are connected to a
single wire
Good points


C

Bad points

D
single wire
everyone is your neighbor



you need an address
you may have to wait to talk to anyone
collisions can occur
communication times become statistical
Physical Addresses

A
0001

If more than two devices are on the same wire (bus),
you will need an address to send and receive data
Approaches

B
1111


Issues

C
D
1000

1100
separate vs. combined data/address lines
hardwired vs. selectable address

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
Virtual Addresses

A
B
C
00
A solution to some physical address problems
is a virtual address

01
10


Approaches


D
11

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
fixed vs. run-time addresses
universal vs. p-to-p addresses
Issues


how to assign them
their relationship to the physical address
Network Technologies

Wired




Phone Line
Power Line
New Wire
Wireless


RF
Infrared
Wired Network Technology Examples

Phone line


Power line





Home Phoneline Networking Alliance (HomePNA)
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)


IEEE 802.3 (Ethernet)



www.homepna.org
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



IEEE 802.3ae



CSMA/CD
Up to 1 Gbps
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:




Takes advantage of chips built into modern
audio and video appliances


Multi-directional AV streams
Event schedule
Registries
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




Video




Coax
RCA
Speaker wire
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


Capable of



but became a general automation control bus
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 surroundsound 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


But it is designed to go much higher


10 Mbps
could run faster than 100 Mbps
But remember

that is faster than most current microcontroller’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


Diffuse – reflective


1m range
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)


Service Agent (SA)


The SLP User Agent is a software entity that is
looking for the location of one or more services.
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)


Service Deregister (SrvDeReg)


Message sent by SAs to DAs containing
information about a service that is available.
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)


SA Advertisement (SAAdvert)


Message sent by DAs to let SAs and UAs
know where they are.
Message sent by SAs to let UAs know
where they are.
Unicast or multicast messaging
Jini



Service discovery for networks of Javaenabled 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 Stack
UPnP Vendor Defined
UPnP Forum Working Committee Defined
UPnP Device Architecture Defined
SSDP
HTTPMU GENA
(Discovery)
SSDP
HTTPU
(Discovery)
UDP
SOAP
(Control)
HTTP
GENA
(Events)
HTTP
(Description)
TCP
IP
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