Tuesday, July 14, 2009

Wireless Routing Protocol

The Wireless Routing Protocol (WRP) is a proactive unicast routing protocol for mobile ad-hoc networks (MANETs). WRP uses an enhanced version of the distance-vector routing protocol. Because of the mobile nature of the nodes within the MANET, the protocol introduces mechanisms which reduce route loops and ensure reliable message exchange.
WRP is a distance vector routing protocol. Each node maintains 4 tables:
Distance table
Routing table
Link cost table
Message Retransmission List table

The wireless routing protocol (WRP), similar to DSDV, inherits the properties of the distributed Bellman-Ford algorithm. To counter the count-to-infinity problem and to enable faster convergence, it employs a unique method of maintaining information regarding the shortest distance to every destination node in the network and the penultimate hop node on the path to every destination node. Since WRP, like DSDV, maintains an up-to-date view of the network, every node has a readily available route to every destination node in the network. It differs from DSDV in table maintenance and in the update procedures. While DSDV maintains only one topology table, WRP uses a set of tables to maintain more accurate information. The tables that are maintained by a node are the following: distance table (DT), routing table (RT), link cost table (LCT), and a message retransmission list (MRL).

The DT contains the network view of the neighbors of a node. It contains a matrix where each element contains the distance and the penultimate node reported by a neighbor for a particular destination. The RT contains the up-to-date view of the network for all known destinations. It keeps the shortest distance, the predecessor node (penultimate node), the successor node (the next node to reach the destination), and a flag indicating the status of the path. The path status may be a simple path (correct), or a loop (error), or the destination node not marked (null). The LCT contains the cost (e.g., the number of hops to reach the destination) of relaying messages through each link. The cost of a broken link is infinity. It also contains the number of update periods (intervals between two successive periodic updates) passed since the last successful update was received from that link. This is done to detect links breaks. The MRL contains an entry for every update message that is to be retransmitted and maintains a counter for each entry. This counter is decremented after every retransmission of an update message. Each update message contains a list of updates. A node also marks each node in the RT that has to acknowledge the update message it transmitted. Once the counter reaches zero, the entries in the update message for which no acknowledgments have been received are to be retransmitted and the update message is deleted. Thus, a node detects a link break by the number of update periods missed since the last successful transmission. After receiving an update message, a node not only updates the distance for transmission neighbors but also checks the other neighbors’ distance, hence convergence is much faster than DSDV.


Friday, July 10, 2009

How to Extend Wireless Range

Maximizing the signal of a wireless network is always a big advantage to a home, business establishment, or workplace. There are many ways of boosting wireless range. Some may require something as simple as relocating the wireless router, while some would need special equipment. One or a combination of these methods will hopefully help extend network range enough to cover an entire home, office, or establishment.

Materials Needed:
- wireless router
- hi-gain antenna (optional)
- USB network adapter (optional)
- wireless repeater (optional)
Step 1
Try relocating the router. Ideally, the router should be placed at the center of the area for maximum coverage in all directions. Also, thick metal and concrete, as well as floors may interfere with the signal of the router so try placing the unit away from these obstructions. Elevating the unit onto a table or mounting it on a wall may also help boost the signal.

Step 2
Try to gauge if the signal has increased by referring to the Wi-Fi client’s signal meter.

Step 3
Try changing the orientation of the router’s antennas (horizontal, vertical, at a certain angle) to see which direction works best to intensify the signal.

Step 4
Go to the wireless router’s configuration page to change channels. Changing the wireless channel, much like fiddling with the dial of a radio to find the best signal, may also help in choosing a channel that is free of interference.

Step 5
Most antennas that come with the router are omni-directional so they broadcast in equal intensity around the router. This will prove inefficient if the router is near an outside wall since half of the signal will go to a place outside the needed area. If this is the case, consider upgrading to a hi-gain antenna. This kind of antenna will concentrate the wireless signal toward only one direction, maybe the area where the router power is most needed.

Step 6
Adding a wireless repeater is one very common way of increasing signal strength. Placing the repeater halfway from the computer and the router will instantly boost the wireless signal. Choose a repeater from the same producer of the router if possible, as hardware coming from the same manufacturers generally work better together.

Step 7
Upgrading the wireless router may prove to be more costly but it is the surest way to actually boost wireless signal. The best in the market, according to most online reviews, is the 802.11n so far. It has been said that this model’s signal provides better range as well as stability. It has also been observed that it crashes less frequently than other models.

Friday, July 3, 2009

How to Encrypt a Wireless Router

A wireless network deployed without adequate encryption is similar to a house without front door with a welcome mat saying thieves are welcomed here at any time. The increasing popularity of Wireless Fidelity (Wi-Fi) networks also led to a need for more reliable protection mechanism which prevents the hijacking of the Internet connection for authorized users of the wireless network. Unfortunately, majority of novice computer owners opt to forego of the process of encrypting the broadcasting of their wireless routers because of the perceived complexity associated with the procedure. This is a dangerous practice because it allows an unhampered access not only to the broadband connection but possibly to the resources of the network clients.

Materials Needed:
- Wireless router
- computer
- Internet connection
- Web browser
Step 1
The process of encrypting the digital signals of the wireless router is not as complicated as it seems. To lock down the router broadcast, open the Web browser and type the IP address of the wireless router in the address page. Possible addresses are,, and among others depending on the device’s manufacturer. Consult your router manual for verification.
Step 2
Entering the correct address will bring up the Administrator login screen for the router. Unless previously modified, possible default usernames are admin, root, or simply a blank box. The possible passwords would be admin or just leaving it blank. The default username and password should be in the device documentation.
Step 3
After successfully entering the correct username and password, the Web Administration Page will be displayed to the user. This is where the encryption of the broadcast will be done.
Step 4
Click on the “Wireless” section of the router configuration page. Choose the section for the “Wireless Security” option.
Step 5
Under the “Security Mode” option, click the dropdown list to select from the possible choices for encryption mode. Each router supports a different range of security methods. More common choices would be WPA (further divided into Personal and Pre-Shared key) and WEP.
Step 6
After choosing the preferred security method, choose the “Wireless Encryption Level” which is normally 64- or 128-bits. The higher the number of bits, the more secured the encryption level is.
Step 7
In the Passphrase field, type a reference text that you can remember. Click on the “Generate” button which will generate a corresponding key based on the Wireless Encryption Level. This code serves as the password for all wireless devices attempting to access the network.
Step 8
Click on the “Save Changes” button to implement the new configuration. Test the broadcast encryption by attempting to connect your wireless device without specifying the network password. The connection should be denied.
Step 9
Repeat the same connection process but this time, type in the generated network key. Click on the “Connect” button. The wireless device should be able to connect to the network. Select the option to save the network key to eliminate the need to type it in at every connection attempt.

Sources: http://www.liutilities.com/how-to/encrypt-a-wireless-router/