This paper is going to address the use of SMS to communicate data between equipment connected via mobile phones and GSM modems. I want to acknowledge that I am not the first author on the subject and the first task is to appreciate the work done so far. The author would like to acknowledges article and contributions in this topic. The phenomenon of SMS data transfer in information technology has been experiencing fast change over the years, (See Fig 1.1 below). This is due to the capabilities brought by wireless networking as the (GSMbrochure, n.d) sated,"Wireless communication means immense flexibility and the possibility to control, monitor and inspect equipment."This paper will interrogate articles, books, journals and various schools of thought on the use of technology devices to communicate data via text message for information systems.
Fig 1.1 Showing SMS usage in European Markets in 1999-2000
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For any equipment to be considered suitable for SMS data transfer we need to make it comply with set rules. These protocols include SMPP, UCP/EMI and SMPP is specifically designed to make message data applications integrate with wireless network. EMI emphasises the type of interfaces that can communicate. As specified by the Etsi organisation (www.etsi.org document 07.05)," Sending or receiving SMS messages through a GSM modem uses the AT command set (instructions to control modems)." The document specification states that the SMS service provider and GSM modem that uses a SIM card linked to GSM network should be connected to send a text message. AT commands that work with GSM and phones are extended and they facilitate receiving and sending of SMS. The terminal sends the characters typed to the modem or phone and displays what comes from the modem on the equipment.
This assertion is very indispensable to the planning and development SMS capable equipment. The etsi organisation (document GSM 03.40 and GSM 03.38) specifies that the text can be 160 characters long each character represented 7-bits. There are two ways the message can be send, text mode or PDU form. AT commands will set the appropriate commands to every data transfer.
The table below shows some of the AT commands and their meaning in sending SMS.
Send message from storage
Fig 1. AT commands and their meaning (www.developershome.com/sms/)
Mobile phone providers give a unique number (SMSC number) to each SIM card and this number is connected to when sending SMS data. So for any equipment to communicate with this mobile SMS device it has to connect to this number. When SQL-RD is part of the set-up it forwards the required information to the respective destination in suitable formats and appropriate frequencies. A close follow-up of this discussion is pointing out to the idea that many technical devices or applications can use SMS as a data transport mechanism to send information to a remote place via mobile phones linked to GSM modems. For instance (Tseng et al., 2003) noted SMS applications such as portable cardiological records and emergency response systems emerging due to GSM popularity. Since SMS messages can carry binary data it has proved to be a reliable data transport.
1.2. A GSM modem can be described as a wireless modem that works with GSM wireless network and sends or receive messages through radio waves. In essence GSM modem is specifically designed for equipment integration. GPRS technology is an extension of GSM and has higher speed in data transmission than GSM. (http://www.developershome.com/sms/GSMModemIntro.asp) has this to say, GPRS can be used as the bearer of SMS. If SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute. Adherents to this idea have even a better way of describing this as; (Li-Chang Lo et al. 2008) stated that USSD is built into the GSM standard for support of transmitting information over GSM network.
Always on Time
Marked to Standard
If this idea is anything to go by then technically GSM modems are a good platform for sending SMS data. There are several ways in which the above mentioned architecture can be implemented. A mobile phone can be connected to a computer via GSM/GPRS modem. AT commands are used to get SMS messages send from mobile phones or GSM/GPRS modem. An alternative way is to get access to respective SMS center of the wireless provider. All SMS messages received will be passed or forwarded to the linked computer or server using the set algorithms or interfaces supported by the wireless carrier. A third access method involves the availability of SMS gateway and all the received messages will be forwarded to the computer or server using supported protocols by the same gateway. The diagram below illustrates how this communication can operate.
SMS messages SMS message PC,laptop mobile phones, PDA with GSM modem/GSM software
Customer message Remote server with
Applications, GSM Control software
ccu SQL,EXCELL,etc SMS message
cellular antenna (www.pixmac.com)
Fig 1.2 illustrates SMS data transfer via mobile phone and GSM modem from Bluetooth equipment.
Regardless of the architecture and applications the software used must allow scripts to talk to modem, phone and Bluetooth devices. Then the server software should be able to talk to the equipment too (in fig1.2 it's the Microsoft's GSM control SMS text message server software). In this scenario Bluetooth devices are sending SMS to server via mobile phone and GSM modem .That said, one needs to understand that on the computer side that's where GSM modem is connected to computer's RS-232 serial port. This layout can promote instant updates of databases and or reply services since messages are 2-way oriented. In the event of a text send from a remote device to another but the network is poor, the SMSC will store the message until the recipient is available. Hence communication via GSM modems and 2G phones can still be reliable even when a remote device is included.
However, the disadvantages are that not all of the modems can properly support SMS data transfer when acting as a modem. The other drawback is that GSM/GPRS cannot hold huge amount of SMS data traffic as explained above. TDMA therefore helps to solve this problem by dividing the time frequency accordingly. GSM utilizes 900 and 1800 MHz frequencies and TDMA technology to send and receive mobile data (Tseng et al, 2005). Hence one is always expected to know his GSM band before purchasing a modem or mobile phone to increase efficiency of data transfer. In some cases this process might include a bit of SMS software or application development which needs some expertise.
Interestingly, through load balancing of SMS traffic this problem can be overcome. In this process each mobile phone/ modem has a number and SIM card. Instructions in form of AT commands are given to each phone or GSM/GPRS modem about how to handle SMS message. The use of API and SDK libraries can be a solution for interaction with mobile phone and GSM/GPRS modem through AT commands. These libraries can provide encapsulation and switching between wireless modem systems SMS and SMSC based messages by modifying configuration files.
3. ( wikipedia.org/wiki/Bluetooth) Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 bands (1Â MHz each) in the range 2402-2480Â MHz This range is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4Â GHz short- range radio frequency band.
In order to fully accomplish this task it has a protocol called L2CAP which can carry up to 64kb payloads and MTU of 672 bytes preconfigured. Around 48bytes is normally set as minimum data size. However, the L2CAP can be reconfigured to suit a given condition hence forth making the channel convenient for sending SMS data across different technology.This is a significant discovery since it promotes data transmission within unlicensed ranges where other devices can get connected. Bluetooth SIG sets the standards and specifications which comply with other market players in wireless communications. The diagram below shows this network layout.
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Fig 1.3 Becker 2007 pg 5. Piconet of two (a) or more (b) devices, scatternet (c)
Therefore the transmission of SMS from Bluetooth devices can be made quite efficient since each devices can do both sending and receiving of data at a given time. Data transmission rate is normally set at 312.5 Âµs intervals. Consequentially mobile phones and GSM modems can also form part of this data transmission network (scatter net). (Harold, 2007) made an enormous discovery about Bluetooth technology. He states that, "Bluetooth is primarily designed for low power consumption with short ranges of 100m, 10m and 1m", however, one has to note in practice these ranges tend to slightly vary. The table below shows some of the ranges that can be covered by Bluetooth technology.
Maximum Permitted Power
Maximum Permitted Power
Fig 1.4 Showing Bluetooth ranges Courtesy of Wikipedia.org
Harold's work on Bluetooth is an encouraging finding it proves that essentially a Bluetooth antenna can work almost like a mobile phone base station. Therefore one can safely conclude that any equipment with this technology can be reliably used in SMS data transmission between equipment connected via mobile phones and GSM modems (as shown in Fig--------). A Bluetooth barcode scanner, camera, PDAs, watch and so on can make remote business or individual peoples' life a bit easier in sending and receiving data in SMS format. Security concerns have been raised on the use of Bluetooth connection. This has always been a cause for concern in wireless communication. (Vainio 2005) maintains that the E22 algorithm together with PIN codes entered on both Bluetooth devices have a great effect in securing the air interface in data transfer. In as much as (Becker 2007) is concerned the weakest link in the wireless connection is the user who apparently picks short and easy PINs, ignorant of security matters and leaves Bluetooth connection permanently switched on. This can be an ideal environment for crime and data theft hence user interaction must be properly informed and trained for maximum data safety.
4. In conclusion this research has proved beyond doubt that devices can send or receive SMS messages via (2G) mobile phones and GSM modem. This is reinforced by the fact that there are set standards for SMS transfer available and any device can be designed to fulfil that goal. Regardless of the architecture chosen, in order for smooth data transfer there is a greater need of user specified software that will integrate various hardware types used. Hence there is a blissful task of promoting SMS data transfer in a 2G populated regions like Africa where internet access is hardly available. Bluetooth devices can be used in creating personal area network (PANs) for efficient SMS data transmission from mobile phones /devices and GSM modems. Proper configuration of wireless protocols significantly simplifies discovery and setup of connection between equipment. Despite what applications are used, there is always a great deal of technical setup, coding or programming to suit users requirements. As the discussion pointed out hand held devices can be used in this case barcode scanner with Bluetooth to send SMS to mobile phones then GSM modems. This will not be the end in its self but can be a means to an end in solving data transfer problems where there is no internet availability like Africa and developing world.