The Wireless Outdoor Router Protocol (WORP) is designed to optimise the performance of outdoor wireless point-to-point and point-to-multipoint links using IEEE 802.11b radios.
Andy Robb, a technology specialist at Duxbury Networking, looks at the role this technology is expected to play in last mile and campus area networking solutions.
Undoubtedly the use of wireless local area networking (WLAN) technology has, in the last few years, significantly changed the way people and enterprises communicate and conduct business.
Mobility within the organisation has become the norm, and the ability to take a wireless equipped notebook from office to office and from the boardroom to basement all the while remaining connected to the corporate network has been a boon to executives "on the go".
But now executives are demanding more mobility. They are looking to radio technology - and the IEEE 802.11b standard - to help them use radio technologies to assist in extending the reach of the corporate WLAN beyond the confines of the building.
With this in mind, companies are now looking for stable, reliable and economical last mile wireless access and campus networking solutions.
This is where the recently developed Wireless Outdoor Router Protocol (WORP) comes in. WORP takes care of the performance degradation that normally occurs when WLAN technology is used for outdoor, building-to-building connectivity as a result of the so-called "hidden-node" problem.
The `hidden-node` problem
The hidden node problem arises because all wireless radio links are programmed to have carrier-sensing (detection of signal) capabilities. This means that each radio transmitter within a given system can "hear" other radio signals and halt their transmission if others are active.
This is easily achieved within a building - but it is not feasible in outdoor point-to-multipoint environments of any significance.
This is because the Request-To-Send/Clear-To-Send (RTS/CTS) signal, when sent from an outdoor subscriber unit to the base station will corrupt any data that other outdoor subscriber units are currently sending.
This results in unnecessary packet loss and multiple re-transmissions, causing the network performance to drop dramatically and even stall.
However, use of the WORP polling algorithm within outdoor 802.11b-standard WLANs ensures that these data packet collisions cannot occur, which increases the performance of the overall network significantly.
More bandwidth
By solving the hidden node problem, WORP can increase the overall net bandwidth of a multipoint system by up to 6 Megabits per second with a corresponding jump in overall performance.
Without WORP, an outdoor installation can begin to suffer from data packet collisions with as few as two remote nodes linked to it.
Using WORP, on the other hand, allows up to 100 remote nodes to be connected without adverse effects on usable bandwidth, allowing more concurrent subscriber units to be active.
WORP also allows the network operator to control network bandwidth, protecting the network from excessive use by any one station.
Undoubtedly, the WORP protocol is more efficient than the protocols used in many legacy outdoor router systems, offering benefits that range from increased net bandwidth and more concurrent subscribers on the same base station to asymmetric bandwidth control and the ability to provide link statistics on demand.
Super-packeting and fragmentation
WORP`s efficiency also comes from the fact that it uses "super-packeting" and "fragmentation" functionalities to improve the effective throughput of the WLAN system by minimising the overhead.
For example, with super-packeting, WORP puts multiple packets into one frame, while fragmentation splits packets over two or more frames.
Super-packeting is useful to pack multiple short messages into a single frame to effectively increase throughput. (Generally, around 60% of IP messages are under 100 bytes.)
Fragmentation, on the other hand, reduces the 802.11b frames to the most efficient data packet size of 2 304 bytes.
WORP security
Security is at or near the top of every network managers` priority list. With WLANs, protection against "car-park" hackers and others with mal-intent is key.
WORP offers a variety of security features for securing data in the network.
Firstly, the protocol is not publicised or standardised, which makes it less vulnerable for hackers than a WiFi-based system.
Then, WORP requires mutual authentication between service provider and user with identification via an MD-5 secret string.
The MD5 algorithm produces as output a 128-bit "fingerprint" or "message digest" of the input. With MD5, it is computationally impossible to produce two messages having the same message digest, or to produce any message having a given pre-specified target message digest.
Additionally, WORP uses 128-bit encryption using WEP+ with weak key avoidance to encrypt the data being sent.
Finally, all remote management methods are password-protected. Different passwords can be set for SNMP read, SNMP read/write, Telnet and HTTP.
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