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SMS TECHNOLOGY

A REPORT ON SMS TECHNOLOGY

Submitted to            Dr. Indrajit Bose Human Resource Department GURU NANAK INSTITUTE OF TECHNOLOGY Date: 20/04/2007

By         				     Amit Ghosh Department: Electronics And Tele-communication Engineering Roll No. 31 4th semester GURU NANAK INSTITUTE OF TECHNOLOGY kolkata,west bengal, India

PREFACE	:

SMS means “ Short Messaging Service”. In this Third Generation (3G) age, the usage of SMS is enhanced day by day. We use this service for exchanging information, or to greet on special days and also SMS is used as a short letter. But this sending and receiving of SMS is too long but quick process. So there should create an interest to know how this service is done that’s how a message goes from a mobile to another. This report is intended to teach the technical students and the SMS users and who has the interest of the process, about the SMS technology. The report on SMS technology consists of a historical background of creation of this technology. After that it’s described about its channel or the way of SMS. Then it’s totally described about the message driving process in this technology. In nutshell, a powerful building block of the modern wireless technological world has been tried to be made more powerful messaging service like 3G technology, for that every user should have the knowledge of this fundamental wireless messaging service.

- Amit Ghosh

ACKNOWLEDGEMENTS:

This report is a self-work in the truest sense of the word. But it will be incomplete without a few heart-felt thank-yous to those people whose expertise and suggestions helped in developing this report. Thank you to Mr. Amitava Das, Prof. Tirtha Sankar Das, Prof. Somnath Maity, without whose guidance this work would have gone in vain. Thank you to Dr. Indrajit Bose without whose guidance this report can’t be written. Last but not the least, thank you to all those persons, whose comments and advice during the survey, gave the report its all-roundness making it an enjoyable yet knowledgeable piece of work.

The raw materials for the report have been collected from various means and sources. Apart from my own personal observations and internal records books like ‘SMS tutorial by ADC telecommunication’, and information obtained from the INTERNET specially from Google search and have been really resourceful.

CONTENTS

Preface …………………………………..………........ 1 Acknowledgement ………………………………..…... 2 1. Introduction - Short Message Service …………………... 4

2. SMS network component …………………………………5

3. Service Element……………………………………………5

4. Messaging process ……………………………..…………6

5. Network Infrastructure ………………………….………8

6. Signaling element …………………………………………9

7. SMS gateway ………………………………………..….. 10

8. Subscriber services ………………………………..………10

9. Application ………………………….…………….………13 . 10.Limitation & Beyond limitation ………………………… 14

11. Problems with SMS………………………………..……. 15

12. Conclusion ……………………………………….…….. 16

Introduction - Short Message Service: Short Message Service (SMS) is on the verge of becoming a big-time player in the wireless marketplace. It is a technology that enables the sending and receiving of messages between mobile phones. SMS first appeared in Europe in 1991. It was included in the GSM (Global System for Mobile Communications) standards right at the beginning. Later it was ported to wireless technologies like CDMA and TDMA. Now in the GPS (Global Positioning System) and 3G(3rd Generation) age SMS is very popular. But there is a thinking how Short messaging service is done, how a text is gone from a device to another.

The point-to-point SMS provides a mechanism for transmitting "short" messages to and from wireless handsets. The service makes use of a short message service center (SMSC) which acts as a store and forward system for short messages. The wireless network provides for the transport of short messages between the SMSCs and wireless handsets. In contrast to existing text message transmission services, such as alphanumeric paging, the service elements are designed to provide guaranteed delivery of text messages to the destination. A distinguishing characteristic of the service is that an active mobile handset is able to receive or submit a short message at any time, independent of whether or not a voice or data call is in progress. SMS also guarantees delivery of the short message by the network. Temporary failures are identified, and the short message is stored in the network until the destination becomes available. SMS is characterized by out-of-band packet delivery and low-bandwidth message transfer.

Initial applications of SMS focused on eliminating alphanumeric pagers by permitting two-way general purpose messaging and notification services, primarily for voice mail. As technology and networks matured, a variety of services were introduced, including Electronic mail and fax integration, paging integration, interactive banking, and information services such as stock quotes. Wireless data applications include downloading of SIM[Subscriber Identity Module] cards for activation, debit, and profile editing purposes.

S MS Network Components:- SMS applications are only as good as the networks that transport them. Following are the four crucial nodes that enable the transmission of SMS messages across the air interface:- Cell Tower or Base Station System: to transmit voice and data traffic between mobile devices and a mobile switching center. Mobile Switching Center (MSC): automatically coordinates and controls call setup and routing between mobile phones in a given service area, maintains individual subscriber records, current status of subscribers, and information on call routing and billing in two subscriber databases called the Home Location Register (HLR) and the Visitor Location Register (VLR). Short Message Service Center (SMSC): acts as a store-and-forward system for relaying short messages. Gateway Mobile Switching Center (GMSC): an MSC capable of receiving short messages from an SMSC. fig. 1 simple diagram of SMS cellular network S ervice elements: Over and above packet structure, SMS includes the following three service elements relevant to short-message transmission and reception: · Validity period - indicates how long the SMSC will guarantee the storage of the short message before ultimate delivery. · Priority - indicates the relative importance of the short message. · Time-stamp reporting - indicates the time of submission of the message and informs the handset whether there are more messages to come.

fig. 2 SMS message structure {service element}

Messaging  Process : When a text message is sent from a mobile,at first it is converted to digital signal and then to analog signal in mobile device and is sent to the wireless network. After that the signal is caught by the base station from the network. Then the signal with service element  goes to MSC. In MSC two subscriber databases (HLR & VLR) are checked like subscriber’s records, current status, billing for that message. After checking this all the signal is sent to SMSC. Using store and forward mechanism attempts to send messages to their recipient’s network.If the recipient is in the same network then it directly works towards recipients mobile but in case of another network there is needed another SMSC of recipients network. Then the recipient’s SMSC forwards the signal towards base station after searching the recipient’s current situation. Then the base station ,after completing the searching of the recipient subscriber, it sends the signal. And again it is converted to digital signal. By this long but quick process we get SMS.[fig. 3 ].                   If a recipient is not reachable, the SMSC queues the message for later retry. Some SMSC s also provide a "forward and forget" option where transmission is tried only once. Both Mobile Terminated (MT), for messages sent to a mobile handset, and Mobile Originating (MO), for those that are sent from the mobile handset, operations are supported. It Message delivery is best effort, so there are no guarantees that a message will actually be delivered to its recipient and delay or complete loss of a message is not uncommon, particularly when sending between networks. Users may choose to request delivery reports, which can provide positive confirmation that the message has reached the intended recipient, but notifications for failed deliveries are unreliable at best.

fig. 3 diagram of SMS Process

Network  Infrastructure: In GSM networks, the type of messaging service is identified by the protocol identifier information element which identifies the higher level protocol or interworking being used.Examples are telex, group 3 telefax, X.400 messaging, ERMES, and voice telephone.In IS41 networks, the service type is distinguished by use of the teleservice identifier.Basic teleservices include the following: · Cellular messaging teleservice (CMT) · Cellular paging teleservice (CPT) · Voice mail notification teleservice (VMN) CMT differs from the CPT due to the inclusion of a reply mechanism which enables a user or network acknowledgment to be selected on a per message basis. The user acknowledgment includes a response code which paves the way for powerful interactive services between SMCs. Many service applications can be implemented combining these service elements. Besides the obvious notification services, SMS can be used in one-way or interactive services providing wireless access to any type of information anywhere. Leveraging new emerging technologies combining browsers, servers, and new markup languages designed for mobile terminals, SMS can enable wireless devices to securely access and send information from the Internet or intranets quickly and cost-efficiently. A generic network infrastructure for realizing the innovative SMS services is depicted in fig. 5 fig. 5 Network Infrastructure S ignaling Elements :

The mobile application part (MAP) layer defines the operations necessary to support the short message service. Both American and international standards bodies have defined a MAP layer using the services of the signaling system No. 7 transaction capabilities part. The American standard is published by Telecommunication Industry Association and is referred to as IS-41. The international standard is defined by the European Telecommunication Standards Institute and is referred to as GSM MAP. The following basic MAP operations are necessary to provide the end-to-end short message service:

· Routing information request: Before attempting short message delivery, the SMSC needs to retrieve routing information in order to determine the serving MSC for the mobile station at the time of the delivery attempt. This is accomplished by way of an interrogation of the HLR, which is accomplished via the use of the SMS request, and sends Routing Info For Short Msg mechanisms in IS41 and GSM respectively.

· Point-to-point short message delivery: The mechanism provides a means for the SMSC to transfer a short message to the MSC which is serving the addressed mobile station and attempts to deliver a message to an MS whenever the MS is registered, even when the MS is engaged in a voice or data call. The short message delivery operation provides a confirmed delivery service. The operation works in tandem with the base station subsystem while the message is being forwarded from the MSC to the MS. Therefore, the outcome of the comprises either success (i.e., delivery to the mobile) or failure caused by one of several possible reasons. The point-to-point short message delivery is accomplished via the use of the Short Message Delivery-Point-to Point (SMD-PP) and forward Short Message mechanisms in IS-41 and GSM respectively.

· Short message waiting indication: The operation is activated when a short message delivery attempt by the SMSC fails due to a temporary failure and provides a means for the SMSC to request the HLR to add an SMSC address to the list of SMSCs to be informed when the indicated mobile station becomes accessible. This short message waiting indication is realized via the use of the SMS notification indicator and set message waiting data mechanisms in IS41 and GSM respectively.

· Service center alert: The operation provides a means for the HLR to inform the SMSC which has previously initiated unsuccessful short message delivery attempts to a specific mobile station, that the mobile station is now recognized by the mobile network to be accessible. This service center alert is accomplished via the use of the SMS notification and alert service mechanisms in IS41 and GSM respectively. SMS Gateway:- One problem of SMS messaging is that SMSCs developed by different companies use their own communication protocol and most of these protocols are proprietary. For example, Nokia has an SMSC protocol called CIMD whereas another SMSC vendor, CMG, has an SMSC protocol called EMI. We cannot connect two SMSCs if they do not support a common SMSC protocol. To deal with this problem, an SMS gateway is placed between two SMSCs. This is illustrated in the following figure. The SMS gateway acts as a relay between the two SMSCs. It translates one SMSC protocol to another one. This way can be used by two different wireless carriers to interconnect their SMSCs for purposes such as enabling the exchange of inter-operator SMS messages. fig. 4 diagram of SMS GATEWAY Subscriber Services:- SMS comprises two basic point-to-point services: · Mobile-originated short message (MO-SM) · Mobile-terminated short message (MT-SM)

Mobile-originated short messages are transported from the handset to the SMSC and can be destined to other mobile subscribers or for subscribers on fixed networks such as paging networks or electronic mail networks. Mobile-terminated short messages are transported from the SMSC to the handset and can be submitted to the SMSC by other mobile subscribers via MO-SM or by other sources such as voice mail systems, paging networks, or operators. For MT-SM, a report is always returned to the SMSC either confirming the short message delivery to the handset or informing the SMSC of the short message delivery failure and identifying the reason for failure. Similarly, for MO-SM, a report is always returned to the handset either confirming the short message delivery to the SMSC or informing the handset of the encountered failure identifying the reason. Depending on the access method and the encoding of the bearer data, the point-to-point short messaging service conveys up to 190 characters to a short message entity (SME). For messages requiring immediate delivery, only one message delivery attempt is made per service request. For messages not requiring immediate delivery, one or more delivery attempts are made until an acknowledgment is received.

· Mobile-Terminated Short Message Example:

Figure 5 depicts the successful MT-SM scenario. For convenience, the GSM method is illustrated. However, the IS41 method is similar.

Figure 5: MT-SM Scenario

1. The short message is submitted from the SME [short message entity ] to the SMSC. 2. After completing its internal processing, the SMSC interrogates the HLR and receives the routing information for the mobile subscriber. 3. The SMSC sends the short message to the MSC using the forwardShortMessage operation. 4. The MSC retrieves the subscriber information from the VLR. This operation may include an authentication procedure. 5. The MSC transfers the short message to the MS [Mobile Station ]. 6. The MSC returns to the SMSC the outcome of the forwardShortMessage operation. 7. If requested by the SME, the SMSC returns a status report indicating delivery of the short message.

· Mobile-Originated Short Message Example:

Figure 6 depicts the successful MO-SM scenario. For convenience, the GSM method is shown. However, the IS41 method is similar.

Figure 6: MO-SM Scenario

1. The MS transfers the Short Message to the MSC. 2. The MSC interrogates the VLR to verify that the message transfer does not violate the supplementary services invoked or the restrictions imposed. 3. The MSC sends the short message to the SMSC using the forwardShortMessage operation. 4. The SMSC delivers the short message to the SME. 5. The SMSC acknowledges to the MSC the successful outcome of the forwardShortMessage operation. 6. The MSC returns to the MS the outcome of the MO-SM operation.

Applications  of   SMS   technology   :

Some of the potential applications of SMS technology, utilizing both MT-SM and MO-SM where appropriate, are:

· Notification services:        Notification services are currently the most widely deployed SMS services. Examples of notification services using SMS include the following: voice/fax message notification, which indicates that voice mail messages are present in a voice mailbox; e-mail notification, which indicates that e-mail messages are present in an e-mail mailbox; and reminder/calendar services, which enables reminders for meetings and scheduled appointment.

· E-mail interworking or SMS over SMTP:    Existing e-mail services (e.g., SMTP, X.400) can be easily integrated with SMS to provide duplex e-mail to short messaging. Some wireless carriers expose a Simple Mail Transport Protocol (SMTP) interface to send SMS. According to one scenario, the email address "is" the device's phone number or pager identification number prepended to the carrier's specific domain; for example, 9831660389@airtelkol.com. SMTP is free to the sender. SMS brokers offer software development kits for implementing the protocol. Some disadvantages of SMS over SMTP include: lack of speed, uncertain (that is, non-guaranteed) delivery, and inconsistent or non-existent error checking. Email simply wasn't designed to provide quick, guaranteed delivery.

· Paging interworking: Paging services (e.g., TAP, TNPP, TDP) integrated with SMS would allow digital wireless subscribers to be accessible via existing paging interfaces.

· Information services: A wide variety of information services can be provided by the SMS, including weather reports, traffic information, entertainment information (e.g., cinema, theater, concerts), financial information (e.g., stock quotes, exchange rates, banking, brokerage services), and directory assistance.

Limitataions : - · As suggested by the name "Short Message Service", the data that can be held by an SMS message is very limited. One SMS message can contain at most 140 bytes (1120 bits) of data, so one SMS message can contain up to: => 160 characters if 7-bit character encoding is used. (7-bit character encoding is suitable for encoding Latin characters like English alphabets.) =>70 characters if 16-bit Unicode UCS2 character encoding is used. (SMS text messages containing non-Latin characters like Chinese characters should use 16-bit character encoding.). · One drawback of the SMS technology is that one SMS message can only carry a very limited amount of data. To overcome this drawback, an extension called concatenated SMS (also known as long SMS) was developed. A concatenated SMS text message can contain more than 160 English characters. Concatenated SMS works like this: The sender's mobile phone breaks down a long message into smaller parts and sends each of them as a single SMS message. When these SMS messages reach the destination, the recipient mobile phone will combine them back to one long message.The drawback of concatenated SMS is that it is less widely supported than SMS on wireless devices. Beyond Limitation :- Besides text, SMS messages can also carry binary data. It is possible to send ringtones, pictures, operator logos, wallpapers, animations, business cards (e.g. VCards) and WAP configurations, bookmarks or profile to a mobile phone with SMS messages.

Problems with  SMS:

After all is said and done, several problems persist in the SMS space, holding back full-scale implementation of SMS. Here are some of the more conspicuous problems, according to Joe Lauer of SimpleWire and Jack Gold of the Meta Group: SMS is a description of a service provided by wireless carriers, rather than a description of a method of delivery. As a consequence, methods of delivery differ and interoperability difficulties prevail. Enterprises should look on SMS as a convenience, not as a high-reliability interaction mechanism. SMS is not a particularly robust system - users may get messages minutes or hours later if they're roaming, or out of range of an SMSC. Companies should rely on SMS as a notification mechanism only when guaranteed delivery and real-time customer interactivity are not issues. Fragmentation of carriers: Over and above inconsistent transports, carriers do not typically allow public access to their networks. Many SMS developers opt to bypass the carrier and implement their own solutions. Alternatively, developers opt to ally themselves with an SMS broker and incur additional fees for service. Unsatisfactory interoperability among carriers: Difficulties are often encountered in sending SMS messages among carriers because of implementation differences. Payment models also differ significantly among carriers. Differing capabilities of devices: Some devices support one-way text messaging, others support two-way. Some can receive only 140 characters per message. Others support concatenations of SMS messages. Some can download binary data, others can't. Developers must maintain extensive information about each carrier and every device.

Conclusion: Problems with SMS aside, it seems safe to say that mobile handsets will do for data in the 21st century what the transistor radio did for music in the 1950s. And SMS is poised to be an important part of this mix, spreading a new and different form of text-based information and entertainment to the masses. With the inclusion of support for binary data in EMS and MMS, a brave new world of text, images, cartoons, audio and video clips transmitted instantly to users on the move may give a whole new meaning to, not just short messages, but short attention spans as well. SMS usage for these purposes are slowly being superseded by GPRS services due to their lower overall costs. =======================

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