domingo, 28 de noviembre de 2010

Applications of Mesh networks

Mesh networks may involve either fixed or mobile devices. The solutions are as diverse as communication needs, for example in difficult environments such as emergency situations, tunnels and oil rigs to battlefield surveillance and high speed mobile video applications on board public transport or real time racing car telemetry. A significant application for wireless mesh networks is VoIP. By using a Quality of Service scheme, the wireless mesh may support local telephone calls to be routed through the mesh. For example, miner safety has improved with VOIP phones communicating over a mesh network.

Some current applications:
U.S. military forces are now using wireless mesh networking to connect their computers, mainly ruggedized laptops, in field operations. It enables troops to know the locations and status of every soldier or marine, and to coordinate their activities without much direction from central command. Video Clip
Electric meters now being deployed on residences transfer their readings from one to another and eventually to the central office for billing without the need for human meter readers or the need to connect the meters with cables.[citation needed]
The laptops in the one laptop per child program use wireless mesh networking to enable students to exchange files and get on the Internet even though they lack wired or cell phone or other physical connections in their area.

The 66-satellite Iridium constellation operates as a mesh network, with wireless links between adjacent satellites. Calls between two satellite phones are routed through the mesh, from one satellite to another across the constellation, without having to go through an earth station. This makes for a smaller travel distance for the signal, reducing latency, and also allows for the constellation to operate with far fewer earth stations that would be required for 66 traditional communications satellites.

Marlon Guerrero



Wireless mesh Architecture

Wireless mesh architecture is a first step towards providing high-bandwidth network over a specific coverage area. Wireless mesh architectures infrastructure is, in effect, a router network minus the cabling between nodes. It's built of peer radio devices that don't have to be cabled to a wired port like traditional WLAN access points (AP) do. Mesh architecture sustains signal strength by breaking long distances into a series of shorter hops. Intermediate nodes not only boost the signal, but cooperatively make forwarding decisions based on their knowledge of the network, i.e. perform routing. Such an architecture may with careful design provide high bandwidth, spectral efficiency, and economic advantage over the coverage area.

Example of three types of wireless mesh network:
Infrastructure wireless mesh networks: Mesh routers form an infrastructure for clients.
Client wireless mesh networks: Client nodes constitute the actual network to perform routing and configuration functionalities.
Hybrid wireless mesh networks: Mesh clients can perform mesh functions with other mesh clients as well as accessing the network.

Wireless mesh networks have a relatively stable topology except for the occasional failure of nodes or addition of new nodes. The traffic, being aggregated from a large number of end users, changes infrequently. Practically all the traffic in an infrastructure mesh network is either forwarded to or from a gateway, while in ad hoc networks or client mesh networks the traffic flows between arbitrary pairs of nodes.

Marlon Guerrero



Wireless mesh network

A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. The mesh clients are often laptops, cell phones and other wireless devices while the mesh routers forward traffic to and from the gateways which may but need not connect to the Internet. The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network. A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes. The animation below illustrates how wireless mesh networks can self form and self heal. Wireless mesh networks can be implemented with various wireless technology including 802.11, 802.16, cellular technologies or combinations of more than one type.

A wireless mesh network can be seen as a special type of wireless ad-hoc network. It is often assumed that all nodes in a wireless mesh network are immobile but this need not be so. The mesh routers may be highly mobile. Often the mesh routers are not limited in terms of resources compared to other nodes in the network and thus can be exploited to perform more resource intensive functions. In this way, the wireless mesh network differs from an ad-hoc network since all of these nodes are often constrained by resources.

The principle is similar to the way packets travel around the wired Internet — data will hop from one device to another until it reaches its destination. Dynamic routing algorithms implemented in each device allow this to happen. To implement such dynamic routing protocols, each device needs to communicate routing information to other devices in the network. Each device then determines what to do with the data it receives — either pass it on to the next device or keep it, depending on the protocol. The routing algorithm used should attempt to always ensure that the data takes the most appropriate (fastest) route to its destination.

Marlon Guerrero



Wireless community network

Wireless community networks or wireless community projects are the organizations that attempt to take a grassroots approach to providing a viable alternative to municipal wireless networks for consumers.

Because of evolving technology and locales, there are at least four different types of solution:
Cluster: Advocacy groups which simply encourage sharing of unmetered internet bandwidth via Wi-Fi, may also index nodes, suggest uniform SSID (for low-quality roaming), supply equipment, dns services, etc.
Mesh: Technology groups which coordinate building a mesh network to provide Wi-Fi access to the internet
WISP: A mesh that forwards all traffic back to consolidated link aggregation point(s) that have centralized access to the internet

WUG: A wireless user group run by wireless enthusiasts. An open network not used for the reselling of internet. Running a combination of various off the shelf WIFI hardware running in the license free ISM bands 2.4 GHz/5.8 GHz

Certain countries regulate the selling of internet access, requiring a license to sell internet access over a wireless network. In South Africa it is regulated by ICASA They require that WISP's apply for a VANS or ECNS/ECS license before being allowed to resell internet access over a wireless link. The cluster and mesh approaches are more common but rely primarily on the sharing of unmetered residential and business DSL and cable Internet. This sort of usage might be non-compliant with the Terms of Service (ToS) of the typical local providers that deliver their service via the consumer phone and cable duopoly. Wireless community network sometimes advocate complete freedom from censorship, and this position may be at odds with the Acceptable Use Policies of some commercial services used. Some ISPs do allow sharing or reselling of bandwidth.

Marlon Guerrero



Uses of Wireless

Wireless networks have continued to develop and their uses have grown significantly. Cellular phones are part of huge wireless network systems. People use these phones daily to communicate with one another. Sending information overseas is possible through wireless network systems using satellites and other signals to communicate across the world. Emergency services such as the police department utilize wireless networks to communicate important information quickly. People and businesses use wireless networks to send and share data quickly whether it be in a small office building or across the world.

Another important use for wireless networks is as an inexpensive and rapid way to be connected to the Internet in countries and regions where the telecom infrastructure is poor or there is a lack of resources, as in most developing countries.

Compatibility issues also arise when dealing with wireless networks. Different components not made by the same company may not work together, or might require extra work to fix these issues. Wireless networks are typically slower than those that are directly connected through an Ethernet cable.

A wireless network is more vulnerable, because anyone can try to break into a network broadcasting a signal.Many networks offer WEP - Wired Equivalent Privacy - security systems which have been found to be vulnerable to intrusion. Though WEP does block some intruders, the security problems have caused some businesses to stick with wired networks until security can be improved. Another type of security for wireless networks is WPA - Wi-Fi Protected Access. WPA provides more security to wireless networks than a WEP security set up. The use of firewalls will help with security breaches which can help to fix security problems in some wireless networks that are more vulnerable.

Marlon Guerrero



Types of wireless connections

Wireless PAN

Wireless Personal Area Networks (WPANs) interconnect devices within a relatively small area, generally within reach of a person. For example, Bluetooth provides a WPAN for interconnecting a headset to a laptop. ZigBee also supports WPAN applications. Wi-Fi PANs are also getting popular as vendors have started integrating Wi-Fi in variety of consumer electronic devices. Intel My WiFi and Windows 7 virtual Wi-Fi capabilities have made Wi-Fi PANs simpler and easier to set up and configure.

Wireless LAN

A wireless local area network (WLAN) links two or more devices using a wireless distribution method (typically spread-spectrum or OFDM radio), and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network.
Wi-Fi: Wi-Fi is increasingly used as a synonym for 802.11 WLANs, although it is technically a certification of interoperability between 802.11 devices.
Fixed Wireless Data: This implements point to point links between computers or networks at two locations, often using dedicated microwave or laser beams over line of sight paths. It is often used in cities to connect networks in two or more buildings without physically wiring the buildings together.

Wireless MAN

Wireless Metropolitan area networks are a type of wireless network that connects several Wireless LANs.

WiMAX is the term used to refer to wireless MANs and is covered in IEEE 802.16d/802.16e.

Wireless WAN

wireless wide area networks are wireless networks that typically cover large outdoor areas. These networks can be used to connect branch offices of business or as a public internet access system. They are usually deployed on the 2.4 GHz band. A typical system contains base station gateways, access points and wireless bridging relays. Other configurations are mesh systems where each access point acts as a relay also. When combined with renewable energy systems such as photo-voltaic solar panels or wind systems they can be stand alone systems.

Mobile devices networks

With the development of smart phones, cellular telephone networks routinely carry data in addition to telephone conversations:
Global System for Mobile Communications (GSM): The GSM network is divided into three major systems: the switching system, the base station system, and the operation and support system. The cell phone connects to the base system station which then connects to the operation and support station; it then connects to the switching station where the call is transferred to where it needs to go. GSM is the most common standard and is used for a majority of cell phones.[5]
Personal Communications Service (PCS): PCS is a radio band that can be used by mobile phones in North America and South Asia. Sprint happened to be the first service to set up a PCS.

D-AMPS: Digital Advanced Mobile Phone Service, an upgraded version of AMPS, is being phased out due to advancement in technology. The newer GSM networks are replacing the older system.

Marlon Guerrero



802.11 Wireless Standard

Before setting up wireless network, you need to understand 802.11 wireless standard that can be used. 802.11a, 802.11b and 802.11g are three popular wireless communication standards. Wireless networks can be built using any of the three, but each has its advantages and disadvantages. 


In September of 1999, the IEEE 802 committee extended the 802.11 standard, created 802.11b standard. It became popular due to low setup cost and bandwidth support up to 11Mbps in the 2.4GHz S-Band Industrial, Scientific, and Medical (ISM) frequency range. For your information, the maximum bandwidth supported by original 802.11 standard is only 2Mbps.

Being an unregulated frequency, 802.11b device can suffer interference from other wireless users, cordless phones, microwave ovens and other devices using the same 2.4 GHz band. However the interference can be avoided by placing 802.11b device a reasonable distance from other devices.


802.11a was created the same time with 802.11b with the ability to support 55Mbps in the 5GHz band. 802.11a is not popular due to the slow availability of the 5 GHz components needed to implement products by vendor, more expensive cost and not compatible with 802.11b. The higher frequency also makes 802.11a signals have more difficulty to penetrate walls and other obstructions.

However the advantage of 802.11a is that it operates at a radio frequency that's less clogged by competing signals from other wireless users, cordless phones and microwave ovens. Its maximum bandwidth is higher as well comparing to 802.11b. 802.11a is usually found on business networks whereas 802.11b better suits the home network.


Due to 802.11b is not compatible with 802.11a and there are needs for higher bandwidth, 802.11g was ratified in June 2003 to provide high data rate and maintain backward compatibility with 802.11b products.

802.11g supports bandwidth up to 55Mbps in the 2.4GHz band. 802.11g is compatible with 802.11b products because they both use the same radio frequency (2.4GHz) to transmit data over the airwaves, it means 802.11g wireless router will be able to talk to 80.11b wireless adapter. 802.11g also provides better security features, such as WiFi Protected Access (WAP) and WPA2 authentication with pre-shared key or RADIUS server.

Again, 802.11g also suffers from the same interference as 802.11b in the already crowded 2.4 GHz range, but can be avoided by placing 802.11g device a reasonable distance from other devices


802.11n is latest wireless communication standard that was approved by IEEE in October 2009, and it can provide bandwidth up to 600Mbps, 10 times faster than 802.11g.

Prior to the release of this final approved 802.11n, several vendors already produced the wireless products based on 802.11n draft standard and they're called 802.11pre-n or 802.11n(draft) wireless products, and it's good to know that the 802.11n wireless product is backward compatible with those draft-n products.

Furthermore, 802.11n can operate in 2.4GHz or 5GHz band, and is backward compatible with 802.11a (5GHz band), 802.11b (2.4GHz band) and 802.11g (2.4GHz band) products.

If you want to set up a wireless network, you can use wireless products that support 802.11n standard that supports much higher bandwidth, but it's more expensive if you compare to 802.11g products.

Marlon Guerrero



Setting Up Ad Hoc Wireless Network in Windows XP

Do you know that you can set up ad hoc wireless network to share Internet Connection at home without using router and switch? Of course you can also use it to share files or printer between 2 or more computers wirelessly.

Please note you can have up to 9 wireless clients in an ad-hoc wireless network, which the computers send their data directly to each other. The only drawback of this approach is its limited wireless range support. You would need to have wireless router or access point for better wireless coverage.

IP Address Allocation: 

You need to allocate the IP address to each computer that involves in this ad-hoc wireless network. If you have 3 computers, you can simply assign, and to each computer with netmask

Host Computer Configuration

1) Let's start with the configuration, here I will choose one computer to start the configuration, right click wireless adapter and then click properties.

Note: Please enable this host computer's ad hoc configuration on ICS host computer if you want to use Microsoft's Internet Connection Sharing feature.

2) Wireless Network Connection Properties will appear. Click Wireless Networks tab, here I tick Use Windows to configure my wireless network settings. After that click Advanced button.

Note: You can also use the configuration tool provided by wireless adapter manufacturers to configure ad hoc wireless network.

3) Advanced window will appear. Select Computer-to-computer (ad hoc) networks only option. Click Close at last.

Note: Don't tick Automatically connect to non-preferred networks in order to ease the configuration.

4) After that, click Add to add new ad hoc wireless network.

5) Name your ad hoc network, here I use home-adhoc. Try to use open authentication without encryption first. After tested it works well, only proceed to enable WPA or WEP encryption. Click OK at last.

6) Now you will see your created ad hoc network (PC card icon) in preferred networks list. Wooo.. You have finished configuring this host computer.

Client Computer Configuration

1) On other client computers, you only need to set its wireless adapter to use Windows to configure its network settings and enable Computer-to-computer (ad-hoc) networks only. Simply follow step 2 and 3 on host computer configuration above to get it done.

2) You then right click wireless adapter to view available wireless networks, you will see your ad hoc wireless network, proceed to connect to it. At this stage, you should be able to connect to this ad hoc wireless network!!! Have fun… :o)

Note: If you have Internet Connection Sharing enabled on host computer, you can just set each client computer to obtain an IP address automatically, then these computers should be able to access Internet.

Marlon Guerrero



Wireless Operating Mode

The IEEE 802.11 standards specify two operating modes: infrastructure mode and ad hoc mode.

Infrastructure mode is used to connect computers with wireless network adapters, also known as wireless clients, to an existing wired network with the help from wireless router or access point. The 2 examples which I specified above operate in this mode.

Ad hoc mode is used to connect wireless clients directly together, without the need for a wireless router or access point. An ad hoc network consists of up to 9 wireless clients, which send their data directly to each other.

Marlon Guerrero



What is wireless network?

Wireless network is a network set up by using radio signal frequency to communicate among computers and other network devices. Sometimes it's also referred to as WiFi network or WLAN. This  network is getting popular nowadays due to easy to setup feature and no cabling involved. You can connect computers anywhere in your home without the need for wires.

Here is simple explanation of how it works, let say you have 2 computers each equipped with wireless adapter and you have set up wireless router. When the computer send out the data, the binary data will be encoded to radio frequency and transmitted via wireless router. The receiving computer will then decode the signal back to binary data.

It doesn't matter you are using broadband cable/DSL modem to access internet, both ways will work with wireless network. If you heard about wireless hotspot, that means that location is equipped with wireless devices for you and others to join the network. You can check out the nearest hotspots from your home here.

The two main components are wireless router or access point and wireless clients.

Marlon Guerrero