GSM - Global System for Mobile communication

is a digital mobile telephone system that is widely used in Europe and other parts of the world. It operates at either the 900 MHz or 1800 MHz frequency band.

GSM is the de facto wireless telephone standard in Europe. GSM has over 120 million users worldwide and is available in 120 countries, according to the GSM MoU Association.

Fig. 1 – a typical GSM network

High-Speed Circuit-Switched Data (HSCSD)

is circuit-switched wireless data transmission for mobile users at data rates up to 38.4 Kbps, four times faster than the standard data rates of the Global System for Mobile (GSM) communication.

HSCSD is comparable to the speed of many computer modemsthat communicate with today's fixed telephone networks. HSCSD is an evolutionary technology on the way to Universal Mobile Telecommunications Service (UMTS).

Fig2. – HSCSD

General Packet Radio Service (GPRS)

is a packet-based wireless communication service that promises data rates from 56 up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users.

GPRS is based on Global System for Mobile (GSM) communication and complements existing services such circuit-switched cellular phone connections and the Short Message Service (SMS).

UMTS (Universal Mobile Telecommunications System )

Short for Universal Mobile Telecommunications System, a 3Gmobile technology that will deliver broadband information at speeds up to 2Mbit s/sec.

Besides voice and data, UMTS will deliver audio and video to wireless devices anywhere in the world through fixed, wireless and satellite systems.

WLAN (802.11)

A wireless LAN is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection.

A standard, IEEE 802.11, specifies the technologies for wireless LANs. The standard includes an encryption method, the Wired Equivalent Privacy algorithm.

LAN

Fig3. – WLAN usage

Bluetooth

Bluetooth is a computing and telecommunications industry specification that describes how mobile phones, computers, and personal digital assistants (PDAs) can easily interconnect with each other.

Bluetooth requires that a low-cost transceiver chip be included in each device. The tranceiver transmits and receives in a previously unused frequency band of 2.45 GHz that is available globally (with some variation of bandwidth in different countries).

Fig3. – Possible Bluetooth usage

Limitations of the mentioned technologies...

When chosing the means of inter-device or other communication we have to keep the technology‘s intended purpose and limitations in mind.

Think of what could prove to be limiting the use of WLAN, Bluetooth GPRS or even GSM. How are range and cost of installation/service connected to each other?

PDA (personal digital assistant)

is a term for any small mobile hand-held device that provides computing and information storage and retrieval capabilities forpersonal or business use, often for keeping schedule calendars and address book information handy.

The term handheld is a synonym. Many people use the name of one of the popular PDA products as a generic term. These include3Com's PalmPilot and the Compaq iPaq.

Fig4. – Modern day PDA (Palm Tungsten)

Smartphones

The term smartphone is sometimes used to characterize a wireless telephone set with special computer-enabled features not previously associated with telephones. In addition to functioning as an ordinary telephone, a smartphone's features may include:

• Wireless e-mail, Internet, Web browsing, and fax

• Personal information management

• LAN connectivity

Fig5. – Selection of smart phones

Other mobile devices

• Notebooks (equipped with WLAN/GPRS cards)

• On-board car computers

• GPS (navigation systems)

• Sat. Phones

• ....

Characteristics of mobile services today

Until smartphones and PDA‘s with suffiicient memory support were on the markt, every mobile application was either WAP or message (SMS) based, because the end user‘s clients were not yet capable of storing/executing client-side application.

Even today the premises when creating mobile services are:

• low memory usage on the client side

• low overall bandwidth usage

Characteristics of mobile services today

Even today, mobile services are more push/then pull, take AvantGo‘s (demo) example, the content is configured over a web-interface and then pushed to your mobile device using an AvantGocontent server.

What could be today‘s limitations for mobile services?

The Mobile Information Device Profile (MIDP)

combined with the Connected Limited Device Configuration (CLDC), is the JavaTM runtime environment for today's mobile information devices (MIDs) such as phones and entry level PDAs.

What MIDP provides is the core application functionality required by mobile applications - including the user interface, network connectivity, local data storage, and application lifecycle management - packaged as a standardized Java runtime environmentand set of Java APIs.

Connected/Disconnected use of devices

With GPRS end users for the firs time had the clear advantage of being bale to be online 24/7 though paying only for the data their applications would send and receive.

While the user was using a full slot with GSM, or even multiple connection slots with HSCSD, and was forced to switch between online/offline mode all the time, GPRS has brought a near-end to the offline use of mobile clients.