Short Message Service.
SMS has been an interesting and basic feature for any mobile. Since its introduction in 1991, it has become a basic element for a mobile handset. The reason for having this service back in pre GPRS era, was for provding mini data/text services to the user on top of voice calls.
Back then we had E1/T1 links for layer1 transport, each E1 or link capable of carrying 64 Kbps of data.
SS7 signalling stack that was used extensively on these transport layers for transferring signalling information across telecom nodes. The Layer2 message being MTP2, had a limitation of 272 bytes on the payload that it carries. This payload contains the MTP3 headers, SCCP headers, TCAP headers, MAP headers, SMS headers and finally SMS Userdata.
According to me this was the reason that SMS designers at that time had to limit the SMS size to 160 bytes, in order to avoid any kind of segmentation at lower layers.
Now with world moving towards 3G/4G/LTE and probable 5G there are alternative high speed data services on the mobile. So the question remain what is the future of SMS ?
Lets consider an example where in a user is about to receive a message(100 bytes ) in two modes
1. through traditional SMS delivery.
2. through 3G's packet delivery procedures.
The protocol messages that are exchanged between network nodes in SMS is less then that are needed in case 2.
On radio/BSS/RNS side for delivery of SMS there is no need for dedicated access bearer. The SMS is exchanged over NAS/BSSAP signalling messages.
Whereas case 2 requires a dedicated bearer to be established. On top of that, these radio resources will not be released for quite some time. Considering the size of text message, this procedure is wastage of radio resources. As operators want to save on every bit of radio resources this may not go down well with them.
So I guess, SMS is here to stay for some more time.
Post is open for debate..
Though there are many call flows available for SMS on the net, I am not able to resist myself from adding one more. In the subsequent blogs I will try to cover the call flow from client/server point of view as well as from radio interface perspective ( SGSN/MSC <-> RNC/BSC).
SMS has been an interesting and basic feature for any mobile. Since its introduction in 1991, it has become a basic element for a mobile handset. The reason for having this service back in pre GPRS era, was for provding mini data/text services to the user on top of voice calls.
Back then we had E1/T1 links for layer1 transport, each E1 or link capable of carrying 64 Kbps of data.
SS7 signalling stack that was used extensively on these transport layers for transferring signalling information across telecom nodes. The Layer2 message being MTP2, had a limitation of 272 bytes on the payload that it carries. This payload contains the MTP3 headers, SCCP headers, TCAP headers, MAP headers, SMS headers and finally SMS Userdata.
According to me this was the reason that SMS designers at that time had to limit the SMS size to 160 bytes, in order to avoid any kind of segmentation at lower layers.
Now with world moving towards 3G/4G/LTE and probable 5G there are alternative high speed data services on the mobile. So the question remain what is the future of SMS ?
Lets consider an example where in a user is about to receive a message(100 bytes ) in two modes
1. through traditional SMS delivery.
2. through 3G's packet delivery procedures.
The protocol messages that are exchanged between network nodes in SMS is less then that are needed in case 2.
On radio/BSS/RNS side for delivery of SMS there is no need for dedicated access bearer. The SMS is exchanged over NAS/BSSAP signalling messages.
Whereas case 2 requires a dedicated bearer to be established. On top of that, these radio resources will not be released for quite some time. Considering the size of text message, this procedure is wastage of radio resources. As operators want to save on every bit of radio resources this may not go down well with them.
So I guess, SMS is here to stay for some more time.
Post is open for debate..
Though there are many call flows available for SMS on the net, I am not able to resist myself from adding one more. In the subsequent blogs I will try to cover the call flow from client/server point of view as well as from radio interface perspective ( SGSN/MSC <-> RNC/BSC).
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