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SMS & MMS
Contents What is SMS
How it Works Infrastructure Required
What is MMS Infrastructure Required
SMS & MMS
Short Messaging Service (SMS) Also known as Simple Message Service
Intention Designed as a replacement for the Pager
The pager allows text messages to be sent to the device To respond you must get to a phone Still widely used, in
Hospitals Military Police Industry
SMS & MMS
SMS allowed Two way communications of the text messages Maximum character length of 160 characters
This can change though depending on the operator or the character set used Character sets supported are
ASCII + additional European characters Unicode
First Text Was sent in December 1992, to a Vodafone device
Sent by Neil Papworth, saying “Merry Christmas” Standard
Defined by ETSI and is known as “GSM 03.40”
SMS & MMS
SMS Continued The success is SMS was never planned for! It was only ever intended as the Pager replacement, with
limited use This will explain some of the design decisions made
Usage in the UK alone December 2003, 20.5 Billion messages sent over the four largest
operators (news.bbc.co.uk/1/hi/technology/3422475.stm, 2004)
Consider this at 8 Pence a time!
SMS & MMS
GSM At a defined time interval in GSM all devices will listen to a
transmission. This is when a Digital Control Channel (DCCH) packet of
information is being sent across the network. 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) 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
SMS Packet format 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 SMS
What a packet looks like Example SMS transmission packet saying “Hello”(www.spallared.com/nokia/smspdu/smspdu.htm#_Toc485435709, 2003)
SMS & MMS
SMS delivery 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 Using this DCCH format, SMS will work on a large number of
digital networks GSM - Europe PCS - American PDC - Japan
SMS & MMS
SMS Infrastructure One additional server needs adding to the GSM
network Short Message Service Centre (SMSC)
SMSC
GSM SMS InfrastructureBaseStation
BaseStation
HLR
HLR = Home Location Register
Other Mobile Phone
Network
SMS & MMS
SMSC This is a combination of hardware and software
The SMS message will be stored at this location on a FIFO basis 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
SMSC Device is outside of the network
The message will be forwarded to the SMSC of that network, where deliver will be the same as before
SMS & MMS Evolution Operators recognised the massive
potential of data services They looked at developing SMS
Result was Enhanced Messaging Service
Allowed additional data to be sent beyond SMS Text formatting
Multimedia Messaging Service Discussed in this lecture
SMS & MMS
Latest Technology Multimedia Messaging Service (MMS)
Allows the transfer of more than text between mobile devices 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
Is only available on GRPS devices and newer
SMS & MMS
MMS The following are the current standards
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 Pictures
JPEG, GIF, PNG, SVG-Tiny (2D Vector Graphics) Movies
MPEG-4 Sound
SP-MIDI Adaptive Multi Rate (AMR)
Text ASCII Text UTF 8/16
Future Use Allows unlimited expansion
SMS & MMS
MMS Additional information about how to present the
Media can also be transferred If this is not present the device will make the
decision Formats are WML, XML or SMIL
Synchronised Multimedia Integration Language (SMIL) SMIL allows for time dependent display of information Allowing for example a presentation to be shown on the
device
SMS & MMS
MMS Delivery SMS was delivered in a single packet MMS can have a theoretical unlimited
message size 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 Number of packets will depend on the type of
messages sent, as with TCP
SMS & MMS
MMS Transport MMS packets will be transferred using the
WAP protocol in GSM based networks 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 Remember WAP is only a transport protocol
Your WML display is just another user agent
SMS & MMS
MMS Delivery continued MMS message will be transferred in the spare
capacity 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 If you device does not have the storage to display a movie,
then the data can be streamed into your device Reducing the overhead for storage, but increasing the
overhead for the network. This will not be available until 3G (UMTS in Europe)
MMS is not platform dependent Meaning that any mobile system can use this technology
SMS & MMS
Paying for MMS ? SMS was simple the sender paid a set amount
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 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 Multimedia Messaging Service Environment (MMSE)
Generic name for all of the servers which need to provide information to send a MMS These can be in more than one network
Consider this when you are roaming MMS Centre (MMSC)
Storing the MMS message until delivery the same as SMSC MSS Relay
Allows delivery of information over different packet switched networks Records usage for charging Conversion of the messages
This will be based upon the specification of the device Using WAP 2.0
HLR Allows the discovery of the status/location of a device
MMS Value Added Services (VAS) Allowing the adding of high quality multimedia in a MMS, provided by the
operator
SMS & MMS
MMS Future 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
(www.w2forum.com/MMS_Extract.pdf, 2004) Reasons
Uncertainty about the technology Expense Lack of MMS capable devices
The usage of MMS should increase 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
Link MMS standards document
www.wmlclub.com/docs/especwap2.0/WAP-205-MMSArchOverview-20010425-a.pdf
WAP Version 2.0 www.wapforum.org/what/WAPWhite_Paper1.pdf