Abstract

Nowadays, Wireless LAN (WLAN) technology becomes more popular as a choice in providing wireless internet access in company, campus, residential, public area, etc. Wireless Mesh as one of variant innovations of WLAN technology offers an unique solution because it can change or enrich capability of internet network infrastructure that has been there, both of cable based or wireless, more effective and efficient because it can coverage wider service area and hard to reach out without overruling the security, mobility, and QoS.

Wireless Mesh grown up by combining the standard of Wireless LAN 802.11 a/b/g (see the previous article about comparison WLAN a/b/g standard). Technically, 802.11a (5, 8 GHz frequency) standard is used to connect inter AP while the 802.11b/g standard is functioned to connect client device to AP.

Wireless Mesh almost looks like repeater mode configuration, but more extended. Used AP unlimited only 2 AP but it has to be more than 2 AP. Connection inter AP is not have to point-to-point and use physical network but it has been multipoint and wirelessly.

Configuration

Wireless Mesh configuration looks like common wireless LAN configuration. The differentiate are in the common WLAN, AP connected through the cable into intranet/internet network through the HUB/switch, but in the Wireless Mesh not of all AP connected direct through the cable to HUB/Switch. In Wireless Mess possible connection inter AP through wireless network such as in the point-to-multipoint network. Beside that to extend coverage, AP also can connect direct to the client.

This is description of Wireless Mesh:

Picture 1. Wireless Mesh Configuration

Picture 2. Configuration of Wireless Mesh Implementation

Characteristics of Wireless Mesh Network

Basically, this Wireless Mesh solution developed to anticipate the technical limitation in WLAN technology first generation where the connection between each Access Point and Switch still very depending on Ethernet cable network and indirect can give solution based-WLAN technology which more effective and efficient. Biggest problem of the implementation will be there when the coverage area very wide, open, and difficult to access by Ethernet cable network, such as outdoor area. Beside that, Ethernet cable network that required connecting Access Point and this switch technically also has distance limitation.

Wireless Mesh solution introduce a concept with wireless communication inter Access Point such as described in Picture 3.The example of Wireless Mesh implementation in big scale can be seen as the picture below:

Picture 3. an example of wireless mesh implementation

Characteristics and advantages of wireless mesh solution are:

1. Give added value when begin and develop business of wireless high speed internet access.

a. This solution capable to support security and mobility feature.

b. This solution capable to support QoS level that enough well to run triple play application, are affiliation voice, data, and video in one infrastructure.

c. user terminal such as handset, PDA, laptop, and PCMCIA that capable to support WLAN technology based- IEEE 802.11b/g easier to get, common used, and reachable price.

2. Reduce costs of capitalization, installation, and operational.

a. Using wireless connection more economical for connection inter Access Point and Access Point with User Terminal.

b. Capability of auto configuration, self organizing, and self healing that possible to reduce installation and operational cost.

c. Simplification of centralized management network system.

3. Very flexible and efficient solution if it saw from the end user capacity and offered data rate, coverage area that can be included either indoor or outdoor, also some offered application. The advantage of this wireless mesh implementation is capability when covering an area and flexibility in the installation.

Components of Wireless Mesh Network

Architecture of wireless Mesh network built-in from three main elements:

1. Access Point

Access Point functioned to collect, distribute, and route data traffic in coverage area. Access Point also functioned to keep the security and validation of connectivity of one Access Point with the other Access Point and Access Point with User Terminal. Access Point in Wireless Mesh built-in from two subsystem:

§ Access link; Provides connectivity between Access Point with User Terminal that developed based-IEEE 802.11b/g standard that operated in bandwidth 2.4 GHz and capable to support access data rate up to 54Mbps maximum.

§ Transit Link; provides connectivity between an Access Point and the other Access Point and/or to the distribution network based-ethernet cable. This link developed based-IEEE 802.11a standard that operated in bandwidth 5.8 GHz and capable to support access data rate up to 54 Mbps maximum.

Picture 4. Access Point

Picture 5. An example of Access Point as Wireless Mesh

2. Wireless Gateway

Wireless gateway functioned to facilitate connectivity to the public WAN and reach ability in distribution network. Wireless gateway also functioned as central point of the mobility feature implementation and security.

Mobility feature in Wireless Gateway possible for movement user process from one access point to the other ones without loosing the connectivity. For a while, security feature in wireless gateway functioned as second layer in both of security network process which supported by IEEE 802.11a/b/g standard in access link level and transit link. Network security between Access Point and Wireless Gateway implemented through the implementation of IPSec tunnel protocol.

3. Network Operations Support System (NOSS)

Network Operations Support System (NOSS) functioned to provide centralized management system and administration for monitoring and controlling performance and configuration of all elements in wireless mesh network. Some important parts of NOSS are:

§ Optivity Network Management System (ONMS); functioned as central point of management system implementation for all elements in wireless mesh network.

§ Industry-standard: FTP, RADIUS, DHCP, and SNTP Server.

Wireless Mesh Planning

There are things that have to be observed when design the wireless mesh network:

§ Each Access point has to be connected minimum with two another Access Point (two connection transit link) to support self healing feature and rerouting process if there is access point problem.

§ For maximize the network performance, two or more Transit Link have to be connected with Access Point @ NAP; is the Access point that has direct connection (via Ethernet cable) with distribution network based-Ethernet cable.

§ Capacity of network and reachable data rate.

§ Distance between Access point and width coverage area by one access point which based on characteristics of radio propagation in required coverage area.

Table 1. Maximum distance estimation

Installation of Wireless Mesh network especially in Access Point relative more simple because after the installation process and supply the power, access point capable to run process of Transit Link auto-discovery, auto-configuration, and self-organizing.

Things that required to be done before the access point installation in wireless mesh network are:

§ Planning of IP addressing scheme

§ Installation and configuration the management system components (NOSS)

§ Installation and configuration the wireless gateway

§ Installation and configuration the access point @ NAP.

Examples of Application and implementation the wireless mesh network

Some examples of wireless mesh solution implementation:

1. Enterprises

Wireless Mesh solution evaluated most efficient in provides or extend service area of wireless internet access either indoor or outdoor.

§ In university, school, company, manufacture, hospital, airport, convention center, department store, sport center, park, etc.

§ Temporary instalation where the presentation of special events such as in exhibition, olympic games, reconstruction efforts of natural disaster, etc.

2. Internet Service Provider

§ Solution that capable to raise revenue and productivity trade when it seen from the capacity, data rate, wide coverage area, application type, and various offered billing.

3. Government and Military/Police

For growing up the government performance and quality of public safety for the citizen, stimulates business growth in a town or recreation area, and provides internet service in resident settlement, both of urban and rural.

Some Examples of wireless mesh network implementation are in some locations as follow:

1. NASA Kennedy Space Station’s Joint Industry Press Center (JIPC)

This implementation purposed to provides solution of wireless internet access which capable to support the journalist mobility indoor and outdoor the Kennedy Space Center. Wireless Mesh solution possible the journalist to access the internet by using their laptop or PDA and mobile from one area press release to the other press release without loosing the connectivity.

2. University of Arkansas

Wireless Mesh solution possible the colleges to access internet and intranet from each campuss direction both of indoor and outdoor and mobile from one area to the other area in campuss area without loosing conectivity.

3. Taipei City\'s \"M-City\" (Mobile City)

This implementation purposed to provide broadband service of internet access in stations where the crowded passengers, office and trade buildings, also the other important location in Taipei and nowadays believed as biggest implementation of wireless mesh. Wireless mesh solution cover 10.000 Access Point that will be cover 272 Km² coverage areas and services two million inhabitants Taipei.

Conclusion

Things that can take as conclusion from the article above are:

1. Wireless Mesh solution is a variant from WLAN that can used as a solution to fulfill the necessity of wireless internet user

2. Wireless Mesh very compatible if used not only for indoor solution but also for outdoor coverage area.

3. Wireless Mesh technology combine the WLAN technology with IEEE 802.11 a/b/g standard.

4. In Wireless Mesh known two connection types are Access Link and Transit Link.

Gunadi Dwi Hantoro, Author was graduated from STTTelkom and joined in TELKOMRisTI since 1996 as engineer in Wireless Laboratory. Some research activity has been doing related with WiMAX technology and Wireless LAN.

References

1. Wireless Mesh Presentation from Nortel

2. www.nortel.com

3. www.tropos.com

4. Report of Outdoor Hotspot Trial, TELKOM RisTI

5. Teknologi dan Aplikasi Wireless LAN, Gunadi Dwi Hantoro