Transcript Document
SMS &
MMS
Justin Champion
C208 Ext:3723
www.staffs.ac.uk/personal/engineering_and_technology/jjc1
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
Character sets supported are
ASCII + additional European characters
Unicode
First Text
Was sent in December 1992, to a Vodafone device
This can change though depending on the operator or the character set used
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)
HLR = Home Location Register
GSM SMS Infrastructure
Base
Station
SMSC
HLR
Base
Station
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
Evolution
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
Movies
SP-MIDI
Adaptive Multi Rate (AMR)
Text
MPEG-4
Sound
JPEG, GIF, PNG, SVG-Tiny (2D Vector Graphics)
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
MMS Infrastructure
Internet
MMS Infrastructure
Base
Station
MMSE
HLR
MMSE = MMS Environment
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
MMS Centre (MMSC)
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
Storing the MMS message until delivery the same as SMSC
MSS Relay
Consider this when you are roaming
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
Reasons
(www.w2forum.com/MMS_Extract.pdf, 2004)
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-205MMSArchOverview-20010425-a.pdf
WAP Version 2.0
www.wapforum.org/what/WAPWhite_Paper1.pdf
SMS & MMS
Conclusion
SMS
MMS