SMS &
MMS
Justin Champion
C208 Ext:3723
www.staffs.ac.uk/personal/engineering_and_technology/jjc1
SMS & MMS
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Contents
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What is SMS
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How it Works
Infrastructure Required
What is MMS
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Infrastructure Required
SMS & MMS
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Short Messaging Service (SMS)
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Also known as Simple Message Service
Intention
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Designed as a replacement for the Pager
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The pager allows text messages to be sent to the device
To respond you must get to a phone
Still widely used, in
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Hospitals
Military
Police
Industry
SMS & MMS
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SMS allowed
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Two way communications of the text messages
Maximum character length of 160 characters
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Character sets supported are
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ASCII + additional European characters
Unicode
First Text
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Was sent in December 1992, to a Vodafone device
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This can change though depending on the operator or the character set used
Sent by Neil Papworth, saying “Merry Christmas”
Standard
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Defined by ETSI and is known as “GSM 03.40”
SMS & MMS
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SMS Continued
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The success is SMS was never planned for!
It was only ever intended as the Pager replacement, with
limited use
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This will explain some of the design decisions made
Usage in the UK alone
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December 2003, 20.5 Billion messages sent over the four largest
operators
(news.bbc.co.uk/1/hi/technology/3422475.stm, 2004)
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Consider this at 8 Pence a time!
SMS & MMS
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GSM
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At a defined time interval in GSM all devices will listen to a
transmission.
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This is when a Digital Control Channel (DCCH) packet of
information is being sent across the network.
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These DCCH packets are used to transfer essential information into
the devices.
Information like a call is in coming
Paging signals from the Base stations, to work out if a handover is
needed
One of these packet formats is called SMS point to point messaging,
Paging, access control channel (SPACH)
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This message type can be used to carry a text message.
Advantage of this method is a text message can still be delivered
during a phone conversation.
SMS & MMS
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SMS Packet format
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All data is transferred in a single DCCH SPACH packet
SCA
Service Centre
Address
MR
Message Reference
PID
Protocol Identifier
PDU Type
Protocol Data Unit
Type
DA
Destination Address
DCS
Data Coding Scheme
VP
Validity Period
UDL
User Data Length
UD
User Data
SMS & MMS
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SMS
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What a packet looks like
 Example SMS transmission packet saying “Hello”
(www.spallared.com/nokia/smspdu/smspdu.htm#_Toc485435709, 2003)
SMS & MMS
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SMS delivery
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Takes no additional allocation of channels
Will still work on a none packet switched infrastructure
Device does not need to continuously listen for a SMS
delivery warning
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Using this DCCH format, SMS will work on a large number of
digital networks
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GSM - Europe
PCS - American
PDC - Japan
SMS & MMS
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SMS Infrastructure
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One additional server needs adding to the GSM
network
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Short Message Service Centre (SMSC)
HLR = Home Location Register
GSM SMS Infrastructure
Base
Station
SMSC
HLR
Base
Station
Other
Mobile
Phone
Network
SMS & MMS
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SMSC
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This is a combination of hardware and software
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The SMS message will be stored at this location on a
FIFO basis
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If the messages destination is within the local network
The HLR, is queried to find the current location of the intended
device
 The HLR will also inform if the device is currently turned on
 If the device is off then the HLR is informed that there is a
message waiting
 When the device turns on the HLR informs the SMSC
 The message will then be forwarded to the device
If the device is turned on, the message will be forwarded to that
location
SMS & MMS
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SMSC
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Device is outside of the network
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The message will be forwarded to the SMSC of that
network, where deliver will be the same as before
SMS & MMS
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Evolution
Operators recognised the massive
potential of data services
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They looked at developing SMS
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Result was
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Enhanced Messaging Service
 Allowed additional data to be sent beyond SMS
 Text formatting
Multimedia Messaging Service
 Discussed in this lecture
SMS & MMS
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Evolution
SMS & MMS
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Latest Technology
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Multimedia Messaging Service (MMS)
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Allows the transfer of more than text between
mobile devices
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These devices do not need to be compatible!
In the event of a none compatible device being sent a
MMS, they will receive an Internet link instead
 The message can then be view on the Internet at a
later stage
MMS
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Is only available on GRPS devices and newer
SMS & MMS
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MMS
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The following are the current standards
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The standards can be expanded in the future
This is a list of base requirements for devices to be given the title
of MMS compatible
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Pictures
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Movies
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SP-MIDI
Adaptive Multi Rate (AMR)
Text
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MPEG-4
Sound
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JPEG, GIF, PNG, SVG-Tiny (2D Vector Graphics)
ASCII Text
UTF 8/16
Future Use
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Allows unlimited expansion
SMS & MMS
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MMS
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Additional information about how to present the
Media can also be transferred
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If this is not present the device will make the
decision
Formats are WML, XML or SMIL
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Synchronised Multimedia Integration Language
(SMIL)
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SMIL allows for time dependent display of information
Allowing for example a presentation to be shown on the
device
SMS & MMS
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MMS Delivery
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SMS was delivered in a single packet
MMS can have a theoretical unlimited
message size
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In reality the operators/devices will control the size
of the messages
This indicates that the message can not be
delivered in a single packet
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Number of packets will depend on the type of
messages sent, as with TCP
SMS & MMS
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MMS Transport
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MMS packets will be transferred using the
WAP protocol in GSM based networks
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This gives security in the messages
Access to the Internet to move MMS message if
needed to the Internet
The User agent at the application layer is
changed to deal with MMS
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Remember WAP is only a transport protocol
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Your WML display is just another user agent
SMS & MMS
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MMS Delivery continued
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MMS message will be transferred in the spare
capacity
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The media will be trickled to your device
You will only be informed of a message once all of the data
is in the device
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If you device does not have the storage to display a movie,
then the data can be streamed into your device
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Reducing the overhead for storage, but increasing the
overhead for the network.
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This will not be available until 3G (UMTS in Europe)
MMS is not platform dependent
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Meaning that any mobile system can use this technology
SMS & MMS
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Paying for MMS ?
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SMS was simple the sender paid a set amount
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This is now an issue with the potential large
amounts of data to be sent
As MMS can in the future be linked to the Internet
how will pay for data coming from it?
This is an issue which will need resolving
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Billing needs to be as simple as SMS to be effective
 Users do not want to get a bill which says you have
received 0.65 Mbytes of data to most people it means
nothing
SMS & MMS
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MMS Infrastructure
Internet
MMS Infrastructure
Base
Station
MMSE
HLR
MMSE = MMS Environment
SMS & MMS
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Multimedia Messaging Service Environment (MMSE)
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Generic name for all of the servers which need to provide information to
send a MMS
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These can be in more than one network
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MMS Centre (MMSC)
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Allows delivery of information over different packet switched networks
Records usage for charging
Conversion of the messages
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This will be based upon the specification of the device
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Using WAP 2.0
HLR
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Storing the MMS message until delivery the same as SMSC
MSS Relay
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Consider this when you are roaming
Allows the discovery of the status/location of a device
MMS Value Added Services (VAS)
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Allowing the adding of high quality multimedia in a MMS, provided by the
operator
SMS & MMS
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MMS Future
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The initial take up of MMS has not been as good as expected
MMS sending is expected to be 1% of the market this year
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Reasons
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(www.w2forum.com/MMS_Extract.pdf, 2004)
Uncertainty about the technology
Expense
Lack of MMS capable devices
The usage of MMS should increase
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This will reduce the cost of the messages
MMS capable equipment will become available as people naturally
replace there phones
Due to adverts the understanding of the technology is increasing
SMS & MMS
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Link
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MMS standards document
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www.wmlclub.com/docs/especwap2.0/WAP-205MMSArchOverview-20010425-a.pdf
WAP Version 2.0
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www.wapforum.org/what/WAPWhite_Paper1.pdf
SMS & MMS
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Conclusion
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SMS
MMS