GSM-WLL Technology and Its Market Analysis

• The GSM-WLL system, based on the GSM technology, is the most attractive WLL system.
• It is absolutely possible for new operators to quickly enter the telecom market by adopting the GSM-WLL technology as a cut-in point.
• For experienced fixed network operators, they can choose GSM-WLL as a supplement to their existing fixed networks, and finally upgrade the GSM-WLL network into a standard GSM network, thus quickly entering the mobile market.
• For mobile network operators, they can provide WLL services by their existing GSM networks so as to step into the fixed communication market.

1 GSM-WLL Technology

1.1 GSM-WLL System Architecture
AWLL (Wireless Local Loop) is a radio access system for users to access PSTN (Public Switched Telephone Network). It is a substitute for conventional wired access. The GSM-WLL system makes use of GSM technologies to achieve WLL.

  As shown in Figure 1, a GSM-WLL system is composed of GSM system equipment and GSM wireless terminals. The system equipment includes MSC/VLR, HLR/AUC, SMSC, BSC and BTS, among which SMSC is optional. The terminals may be GSM handsets or other GSM terminals such as the radio access station, desktop GSM fixed terminal and public GSM fixed terminal.
The definition of a WLL system keeps changing with its technical development. The V5 interface was

  ever defined as a major characteristic of WLL. However, people pay more attention to the roaming restriction and terminals of WLL system now.

  At present, WLL refers to a wireless system that serves a designated area, and the GSM-WLL system is based on a standard GSM network. Its wireless terminals include diversified access stations made of standard GSM handset modules and plug-in SIM cards. Its numbering and billing policies can be the same as those of PSTN, but the terminals´ mobility is restricted via configuration on the network side. Terminals can only access the public network within a certain area, i.e. without roaming functionality. Therefore, some manufactures call the WLL system a restricted mobility solution.

1.2 Terminals
Due to the openness of GSM interfaces, standard GSM handsets can be directly used as GSM-WLL terminals. Moreover, GSM-WLL system providers have also developed other kinds of WLL terminals. With built-in GSM 900 MHz/1 800 MHz wireless communication modules, and via circuit switch and wireless module interfaces, these terminals can achieve service quality as good as a fixed telephone has. The terminals can easily access the GSM-WLL network and timely and economically provide fixed wireless communication services under the coverage of GSM-WLL network.

  In addition to GSM handsets, ZTE´s GSM-WLL system supports three kinds of terminals to meet various demands: the wireless access station, desktop mobile telephone and outdoor public mobile phone.

1.2.1 Wireless Access Station
A wireless access station is a kind of GSM wireless converter. It offers a common SIM slot, and can receive/send GSM radio signals through GSM wireless communication modules. An ordinary fixed telephone can access the GSM-WLL network via an RJ11 interface.

  With the RJ11 interface, the station has flexible application functions, such as providing fixed phone services when connected with an ordinary fixed telephone, providing one-to-N fixed phone services when connected with a PBX (Private Branch Exchange), and providing fax services when connected with a fax machine.

1.2.2 Desktop Mobile Telephone
 A desktop mobile telephone is a GSM-WLL terminal, integrating the access station and telephone together. It offers a common SIM slot, having the same shape and functions as an ordinary telephone, such as the LCD screen and hand free function. Some models of desktop terminals can send/receive short messages, and some models have the battery supporting 10-15 standby hours. Desktop mobile telephones are mainly applied at homes, offices and watched public phone booths.

1.2.3 Outdoor Mobile Public Telephone
An outdoor mobile public telephone is a GSM-WLL terminal, integrating the access station and IC phone (or pay phone) together. It has the same appearance as an ordinary IC phone (or pay phone), and may be applied at duty-free telephone booths, bus/train stations and docks. The terminal is usually powered by 220 V AC, but has a built-in storage battery.

2 Market Analysis
Apart from the GSM technology, other wireless technologies such as CDMA, DECT and PHS can also be used in a WLL system. But the present position of GSM in the mobile market makes the GSM-WLL system most attractive.

  GSM is the biggest mobile network in the world with matured technologies and products. GSM equipment is featured with open interfaces, powerful coverage, most equipment providers and cheap products. It´s an ideal solution for large-scale coverage at a low cost. In consideration of technology, cost and policy, it is absolutely possible for new operators to quickly enter the telecom market by adopting the GSM-WLL technology as a cut-in point.

  For experienced fixed network operators, they can choose GSM-WLL as a supplement to their existing fixed networks in order to quickly cover remote areas with low costs and acquire more users. At a right time, they can easily upgrade the GSM-WLL network into a standard GSM network, thus quickly entering the mobile market and serving for roaming-in GSM users, which may bring considerable benefits in a short period of time.

  For mobile operators, they can provide WLL services on their existing GSM networks so as to step into the fixed communications market.

  In developed countries, a mobile operator may use a WLL system to cover business buildings to deliver feature services. For example, a new operator signs an agreement with a public network operator to offer the latter´s group users special office phony services by GSM-WLL. When a subscriber enters the WLL-covered area, his/her handset will be automatically switched to the WLL network from a public network. Then his/her calls to others on the same WLL network are treated as internal calls.

  Since the GSM-WLL terminals adopt standard GSM handset modules, it is convenient to provide various WLL terminals to satisfy different demands. Furthermore, sufficient second-hand GSM handsets can be directly used as GSM-WLL terminals or modified into fixed WLL terminals to meet demands of the low-end market.

3 Conclusion
Based on the standard GSM system, the GSM-WLL system can be deployed under different access environments to bring operators quick benefits. It also makes operators more flexible in the evolution of networks. Therefore, the GSM-WLL system will be widely used in the future.