Abstract
`This tutorial presents an overview of the Global System for Mobile Communications Short Message Service from the viewpoint of implementing
`new telcntatic services. SMS offers the users of GSM networks the ability to exchange alphanumeric messages up to the limit of 100 characters.
`The tutorial is motivated by an acute absence of research publications in this field. The information gathered in the tutorial was required
`considering the increasing potential SMS offers for integration with existing messaging services and its ability to offer a successful replacement
`for the Transmission Control and Internet Protocols as far as low-bandwidthdemanding applications are Concerned. initially. the tutorial gives a
`brief overview of the building blocks of GSM networks — the mobile station, base station, and network subsystem -
`- and then emphasizes the
`SMS network and protocol architecture. The most widely used protocols for message submission me then introduced (text—hased, SMSEUOO.
`HIS] LIT-"[15,
`'E‘Al’) and compared in terms oi features provided and flexibility to handle extended alphabets or two-way messaging. Finally the
`tutorial outlines a summary of current and future issues [or further development and research in the light of novel features for submission
`protocols and telematic services.
`
`The Global System for
`Mobile Communications
`
`Short Message Service
`
`GUILLAUME PEERSMAN AND SRBA CVETKOVIC,
`THE UNIVERSITY OF‘ SHEFFIELD
`
`PAUL GRIFFITHS AND HUGH SPEAR, DIALOGUE COMMUNICATIONS LTD.
`
`lilifl-‘J‘Jlfimflfl | [Lilli it?) Zilliti [ERR
`
`to send andl'ot‘ receive alphanumeric messages. The short
`messages can be up to 140 bytes in length, and are delivered
`within a few seconds where GSM coverage is available. More
`than a common paging service, the delivery of the message is
`guaranteed even when the cellular terminal is unavailable
`(c.g., when it is switched off or outside the coverage area}.
`The network will hold the message and deliver it shortly after
`the cellular terminal announces its presence on the network.
`The fact that SMS [through GSM) supports international
`roaming with very low latency makcs it particularly suitable
`for applications such as paging, c-mtlil, and voice mail notifi-
`cation, and messaging services for multiple users. However,
`the facilities offered to users and the charges for these facili—
`ties still mainly depend on the level of service provided by the
`network operator.
`There are two types of SMS available: cell broadcast [1]
`and point-to-poiut [2]. In ccll broadcast, a message is trans—
`mitted to all the active handsets or mobile stations (MSs) pre-
`scnt in a cell that have the capability of receiving short
`messages and have subscribed to this particular information
`service. This service is only one—way, and Ito confirmation of
`receipt will be sent. It can send up to 93 7-hit character or 82
`8-bit characters, typically used to transmit messages about
`traffic conditions, weather forecast, stock market, and so on.
`In point—to—poinl service, messages can be sent from one
`mobile to another or from a PC to a mobile and vice versa.
`These messages are maintaincd and transmitted by an SMS
`Center [SMSC). 'l'he SMSC is an electronic form of ordinary
`The Short Message Service
`mail postal service that stores and [Iron forwards the messages
`when they can be delivered. [inch GSM network IItusl support
`Developed as part of the GSM Phase 2 specification, the
`Short Message Service, or SMS as it is more commonly
`one or more SMSCs to sort and route the messages. L-‘ach
`SMSC checks, organizes, and sends the message to the opera—
`known, is based on the capability of il digital cellular terminal
`
`_since the first: Global System
`for Mobile Communications ((iSM] nctWork started opera—
`tion'in 1991, more than 100 countries have adopted the stan-
`dard. Over 20 million subscribers of GSM networks are now
`offered worldwide coverage, outstanding voice quality over a
`whole range ofoperaling conditions, and :1 variety of value-
`addcd services. These services include voice mail, call him—
`tiling facilities, cell line identification, and Short Message
`Service (SMS).
`Willi SMS, users are able to exchange alphanumeric Ines-
`sagcs (up to 160 characters) with other users of digital cellular
`networks, almost anywhere in the world, within seconds of
`suhrnission. liven if the service was originally conceived as a
`paging mechanism for notifying the users of voiccmail mes-
`sagcs. SMS is now increasingly used as a messaging service.
`The messages are typically created on mobile phone kcypads.
`which is somewhat awkward. Forlnmllely, there are other
`ways to access the message centers. as discussed in this article.
`Numerous applications are already available and make short
`message reception and submission possible using a computer.
`Gateway :trclriteclnrcs are also being widely implemented and
`connect company‘s c-mait or voiccmail system to the SMS.
`The practical implementation of SMS and thc different
`protocols for message sulnnission are addressed in this article.
`The future of SMS and a brief review of the fields currently
`being studicd will conclude this article.
`
`IETEE Personal Fommunicatinns - June 2cm
`
`Facebook Ex. 1012
`U.S. Pat. 8,243,723
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`Base transceiver station
`Base station controller
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`I Figure 'I. The basic GSM network architecture.
`
`tor. It also receiver; and passes on any confirmation messages to
`any GSM mobile on any network. I lowever, in practice. there
`are no agrcclrlents to allow SMS to travel between networks.
`There are several ways in which a short message can he
`submitted, depending on the interfaces supported by the ('ISM
`rrotmrrk SMSC. Users can call a central paging bureau (Lo,
`an operator). or directly create the message on the keypad of
`their handset. ’t‘ypiug the messages is made easier when using
`a personal digital assistant (FDA) or a laptop connected to
`the handset. A few SMSC. equipment nunmfocturers and corn—
`]‘Janies have also developed their own protocols for short mes-
`sage antunisnion. Consequently, more and more GSM
`networks now offer access to their SMSC‘. using these proto—
`eols over a variety of hardware interfaces: modern dialup,
`X25, and even the luternet.
`
`65M Network Architecture
`
`The layout ol‘ a generic GSM network with its several func-
`tional entities is shown in Fig.
`l [3]. Tile architecture can be
`divided in three main components:
`' The subscriber holds the MS, namely the GSM terminal
`' The base station subsystem eomrols the radio link with the
`MS
`' The network subsystem performs the switching of coils and
`other' management tasks such as authentication.
`
`SIM. Because the IMRI and lMSI are independent, personal
`mobility is possible. The SIM can be protected against unau-
`thorized use by a personal identity number (PIN).
`
`The Base Station Subsystem
`The base station subsystem is composed of two parts, the
`basic transceiver station (HTS) and base station controller
`{ESQ}. They communicate across thc specified Atria inter-
`face, thus allowing network operators to use components
`made by different suppliers, The DTS houses the radio
`transceivers that define a cell and handle the radio link pro-
`tocols with the MS. Depending on the density of the area,
`more or fewer B'I'Ss are needed to provide the appropriate
`capacity to the cell. Digital communications system (DCS)
`networks working at illth MHV. need twice the number of
`Il‘l'Ss to cover the same area as GSM networks, but provide
`twice the capacity.
`_
`Tile BSC manages the radio resources for one or more
`BT33; via the standardized Abis interface. It handles radio
`channel setup, frequency hopping, and handovers. The BSC is
`the connection between the MS and the mobile switching cen-
`ter (MSG). The BSC also takes care of converting the 13 ltbls
`voice channel used over the radio link (Um interface) to the
`standardized 64 khls channel used by the public switched tele—
`phone network (PS'I'N).
`
`'l'lrc Network Subsystem
`The Mobile Station
`The M513 is the main component of the netwurk subsystem.
`The MS and base station subsystem communicate across the
`lts provides the some functionality as :1 switching node in a
`Um interface, also known as the air interface or radio link.
`PSTN or integrated sewiecs digital network (ISBN), but also
`takes care of all the functionality needed to handle a mobile
`The base station subsystem ctnnrnunieates with the network
`subscriber such as registration, authentication, location updat—
`subsystem across the A interface. The MS consists of the
`ing, handovers, and routing to a roaming subscriber. The
`physical terminal and contains the radio transceiver. the dis-
`MSC also acts as a gateway to the PSTN or ISBN, and pro—
`play and digital signal processors. and the Subscriber Identity
`vides the interface to thc SMSC.
`Module (SIM The SI M provides the user with the ability to
`The international roaming and call routing capabilities of
`access their subscribed services regardless of the location and
`GSM networks are provided by the home location register
`the terminal used The insertion of the SIM in any GSM cel—
`(HLR) and visitor location register {VLR} together with the
`lular phone allow the user to access :I network, make and
`MSC. The HLR database contains all the administrative infor—
`receive phone calls, and use all the subscribed rcwice-i.
`matiou about caeh registered user of a GSM network along
`The International Mobile Equipment identity (IMEI)
`with the current location of the MS. The current location of
`uniquely identifies the mobile terminal according to the Inter—
`an MS is in the form of a Mobile Station Roaming Number
`national Mobile Subscriber Identity (IMSI) contained in the
`
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`'16
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`IEEE Personal Communications ' June 20th!
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` SMS-GIV'ESC/r
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`SMS-IWMSC
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`'igure 6. protocol loycrfor 1)r)inf;to;1oint.
`
`Fhe SM-TL exchanges PDUs with its peer entity. The
`,7.th message relay layer (SM-RL) conveys the PDUs via the
`ant message link layer (SM—LL). Refer to GSM 03.40 [2] for
`further details.
`
`5M5 Protocol Doto Unit B/pes
`There are six types of TPDU at the SM—TL, as listed in Table
`'l. The elements of the SMS—Deliver and SMS-Submit TPDU
`are shown in Fig. 7 [2]. The main fields of the TPDU are
`described in this document however for a complete descrip—
`tion of the TPDU please refer to GSM 03.40
`
`
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`element data (IED) that follows. Each of
`these fields is ] octet long.
`In the user data, the message can be 7 bits,
`8 bits, or 16 bits. If 7-bit data is used and the
`header does not end on a 7—bit boundary,
`padding bits are used. This is to ensure that
`older mobiles which do not support the TP—UD
`header can still display the message properly.
`Using the IE] allows sending and receiving
`of concatenated short messages. The IED field
`contains all the necessary information for the
`receiving entity to reassemble the messages in
`the correct order, and is coded as follows:
`- First octet: short message reference num-
`ber identifying the message within the same
`transaction
`0 Second octet: specifies the maximum number of short mes-
`sages in the concatenated short message, which will not
`exceed 255
`0 Third octet: identifies the sequence number of the short
`message within the concatenated message
`The minimum [leader length for concatenated message is 7
`octets for 8—bit and [6—bit data and 8 for 7-bit data; leaving 133
`(140 — 7), 152 (160 — 8), and 66 ((140 ~ 7)]2) characters for the
`short message. The maximum length of the message is then
`increased to 38,760 (255*152), 33,915 (255*133), or 16,830
`(255*66) depending on the character ending scheme used.
`
`TP—Dota-Coding—Srheme
`The data coding scheme field (TP—DCS) is used to iden—
`tify the coding scheme used by the user data, which can
`be 7- or 8-bit or even Unicode [6], as defined in GSM
`03.38 [7].
`
`TPeValidiQI—Periorl
`The TP—VP field contains an information element
`
`enabling an MS to specify a validity period for the short
`message it is submitting. The value specifies how long an
`SMSC will guarantee the existence of a short message
`before delivery to the recipient has been carried out.
`
`TP~More—Messoge—To—Send
`"l‘hc SMSC uses the TP-MMS field to inform the MS that
`wine or more short messages are waiting to be delivered.
`
`TP-Uscr—Data-Heoder—lndicotor
`' he 1-bit Tl’»UDHI field indicates whether the 'l‘P—UD
`l .r‘ludes an additional header as well as the short message.
`
`TP—Protocol identifier
`The TP-PID is used by the MS or SMSC to identify the
`higher-layer protocol being used for internetworking
`with a certain type of telematic device (Telefax group 3
`or 4, Ermcs, etc.)
`
`TPileer—Dota {TP-UD)
`The TP-UD field is used to carry the short message. It
`ran store up to 140 octets of data for point-to-point SMS,
`together with a header depending on the setting of the
`'i‘P-UDHI field, The amount of space taken by the header
`reduces the amount of data the PDU can carry. Figure 8
`: hows a representation of the layout of the TP-UD for 7—
`;.nd 8-bit data schemes.
`The header has at least three fields. The first field,
`the information element identifier, is used to identify
`(oncatenated short messages. Information data length
`(lDL) is used to indicate the length of the information
`
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`
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`TP-messagewtype-indicator
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`TP-more-message-to-send
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`TP—repIy-path
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`TPnuser-data-header-indicator
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`TP-originating-address
`TP-protocoI-ID
`TP—data-coding—scheme
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`TP-status-report
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`TP-service-center—time-stamp
`
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`TP-user-data~length
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`TP—u5er—data
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`SMS-deliver
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`i Figure 7.An SMS TL-PDU. "
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`TP-message-type-indicator
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`TP—reject—duplicate
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`TP-Validity-period format
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`TP—reply~path
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`TP-usermdata-header—indicator
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`TP—message reference
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`TP-destination-address
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`TP—data—coding—scheme
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`SMS—subrriit
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`sMessage response>_ <CR> <ACK> <CR>
`
`' <E5CéPGi <PasswordS<CR> '
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`[12] Telocator Alphanumeric Protocol (PCIA) v. 1.2 Functional Spec for TAP-
`AIM ver 2.6 (Aldiscon)
`
`Additional Reading
`[1] M. Rahnema, "Overview of the GSM System and Protocol Architecture,"
`IEEE Common. Mag, vol. 3, no. 4, Apr. 1993, pp. 92400.
`
`Biographies
`GUILLAUME PEERSMAN (G.Peersman@dcs.shef.ac.uk) graduated from the Insti-
`tut Superieur d'Electronique the Paris (ISEP) in 1996 with a double M.Eng.
`in electronics and computer networks. He then joined the University of
`Sheffield, and is currentty reading for a Ph.D. degree in the Computer Sci-
`ence Department. His research interests focus on the development and per-
`formance analysis of two-way messaging gateways for the GSM Short
`Message Service. He also recently extended his field of research to the
`Wireless Application Protocol gateway design.
`
`SRBA R. CVETKOVIC (S.Cvetkovic@dcs.shef.ac.uk) completed his B.Sc. (with
`First Class Honours) and Ph.D. degrees in electronic and electrical engineer-
`ing at City University, London (1983) and University College London (1987),
`respectively. In June 1937, he joined the Department of Electronic and Elec-
`trical Engineering at the University of Surrey as a lecturer in telecommunia
`cations and satellite systems. In September 1992 he moved to the
`Department of Electrical Engineering and Electronics, Brunel University,
`West London, to a senior lectureship in data communications. In Septem—
`ber 1995 he took up the post of senior lecturer in multimedia communica-
`tions systems in the Department of Computer Science at the University of
`Sheffield. In January 1996 he established the Centre for Research, Education
`and Development Online (CREDO). He now leads the Research Group in Com-
`munications and Distributed Systems (CDSRG), which he cowfounded in Octo-
`ber1997 with Prof-Colin Smythe. CDSRG (including CREDO) is currently
`involved in projects of value in excess of US$8.5million and has over 35 full-
`time members of academic, research, and support staff. In October 1997 he
`was promoted to reader (in telematics) and in June 1999 to a personal chair
`in mobile systems, a joint position between the Departments of Electronic and
`Electrical Engineering, and Computer Science. His research interests include
`multimedia/broadband communication systems. satellite communications and
`DSP systems. as well as numerical modeling and measurements of electro-
`magnetic fields. More recently, his focus has been on protocols for supporting
`mobile systems (Mobile IPv6, GSM/SMS) and knowledge management. For
`further information visit http://www.dcs.shef.ac.uk/~srba
`
`PAUL GRIFFiTHS (P.6riffiths@dialogue.co.uk) graduated from Sheffield City Poly-
`technic in 1986 with a 8.5c. Hons. in business studies. He then joined
`Fretwell Downing Data Systems as a software developer where he worked on
`various projects between 1998 and 1991. Between 1991 and 1994 he
`worked on secondment with Sheffield Hallam University to conduct research
`into the development of GUI environments. In 1994 he helped tofound Dia«
`logue Communications Limited who developed a product for GSM short
`messaging called pagemail which has since sold over 500,000 copies. He has
`since been invoIVed with both business and technical aspects of developing
`server products for GSM SMS. He is now co—dirEctor of Dialogue Communica-
`tions Ltd., a specialist SMS software manufacturer which has recorded an
`average growth rate of 7‘0 percent for the last three years.
`
`HUGH SPEAR (H.Spear@dialogue.co.uk) received an M.Sc. with distinction in
`Software Systems Technology from Sheffield University in 1991. Between
`1991 and 1995 he worked as a systems analyst and project leader with
`Fretwetl-Downing Data Systems in Sheffield. In 1995 he co-founded Dia-
`logue Communications Limited, a mobile messaging business which devel-
`ops and markets products and services for messaging over GSM SMSand
`paging services. By the end of 1999 Dialogue had over 250,000 customers
`and products in over 20 countries.
`
`I Figure 12. Short message submission using 7141’.
`
`.
`same transaction
`- Support for distribution list creation and modification with-
`in the SMSC to greatly increase short message throughput
`last but not least, some research projects are studying the pos-
`sibility of using SMS as an alternative layer to TCP/IP, thus
`adding mobility to low-bandwidth applications. Intel’s Narrow
`Band Socket specification first tried to define how applications
`could benefit by using SMS as an alternative to TCP/IP; however,
`this work is now in the process of being superseded by the Wire-
`less Application Protocol (WAP).
`
`
`
`References
`1] ETSI GSM 3.41, “Digital Cellular Telecommunication System (Phase 2);
`Technical Realisation of Short Message Service Cell Broadcast (SMSCB),"
`v. 5.2.0, May. 1996.
`2] ETSI GSM 3.40, "Digital Cellular Telecommunications System (Phase 2+)
`Technical Realisation of the Short Message Service Point—to-Point," v.
`4.13.0, May. 1996.
`3] J. Scourias, “A Brief Overview of GSM,” Univ. of Waterloo; http:,frccngar
`uwaterloo.ca/~jscouriarGSMrgsmreport.html
`4] M. Mouly and M. Pautet. "The GSM System for Mobile Communica-
`tions,” 1992.
`5] W. Roth, "Data Service on the GSM Platform,” GSM Summit Hong
`Kong. Mar. 1993.
`6] ISO/IEC10646, "Universal Multiple Octet Coded Character Set (USC),
`UCSZ, 16 Bit Coding."
`7] ETSI GSM 3.38, "Digital Cellular Telecommunications System (Phase 2+):
`Alphabets and languagerspecific information," v. 5.2, May. 1996.
`B] K. Holley, http:ilthabs.bt.comlpeople/holleyka
`9] CCITT E164, "Numbering Plan of the International Telephone Service,"
`v. 5, 1997.
`-
`[101 GSM 07.05, "Digital Cellular Telecommunications System (Phase 2);
`Use of Data Terminal Equipment — Data Circuit terminating; Equip-
`ment (DTE - DCE) interface for Short Message Service (SMS) and Cell
`Broadcast Service (CBS),“ draft, May 1996.
`[11] SEMA Group Telecommunications. "SMSZOOD v. 4.0, Open Interface
`Specification," INS/F5128.
`
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