It’s hip2b2

After my previous blog entry about WMN and after a bit more reading, two (2) additional important properties emerged that add to the definition of wireless mesh networks (WMN). There two (2) properties are described in brief below.

• Multi-hop. This is to differentiate it from regular Access Point (AP) type wireless networks, WMN has the ability to route packets through multiple hops within the mesh network [1]. AP type networks on the other hand only have one hop from the terminal equipment to the AP. I believe this is a key characteristic of a WMN. It was a wonder why I failed to see this earlier.
• Multi-channel. IEEE 802.11 standards allow the use of multiple channels to prevent base station interference. This is a likely consequence if we put numerous ad-hoc wireless APs within range of each other. There have been a number of studies [2] that describe how these additional channels can also be used to improve the performance of the WMN. Of course, there are more references out their with different inputs on how to use the multiple channels. Some use separate channels for network traffic and network management. Other separate routing and signaling to another channel. Even others channel bond these network interfaces to get more bandwidth for that node. So do it with multiple network interfaces. Others do it with just one but manage frequency usage.

The two (2) additional properties I realized are central to the definition of a WMN. Multi-hop is the key differentiating factor between a WMN and a Wireless AP-based Network. The use of multi-channels are also central in minimizing interference between neighboring nodes in the WMN. This is particularly important as WMN’s tend to be ad-hoc and unplanned increasing the chances of frequency interference. There you have it.

PS. On another note, I also found some interesting ancient references to wireless mesh networking technology. They are interesting reads. The one about DARPA’s PRNET [3] describes a lot of interesting technologies and implementations that look like (but are not quite the same) to a number of technology we commonly use today like CSMA (IEEE 802.3), CDMA (used in CMTS) and logical addressing (probable precursor to ARP and RARP). Their CDMA description for maximize radio spectrum is particularly interesting because they use the DES cipher as their PN code generator. Now, I wonder what PN code generator is used today? A simple LFSR or Feistel structure?

[1] J Bicket and D Aguayo and S Biswas and R Morris. 2005. Architecture and evaluation of an unplanned 802.11 b mesh network. Proceedings of the 11th annual international conference on Mobile computing and networking. New York.
[2] A Raniwala and T Chiueh. 2005. Architecture and Algorithms for an IEEE 802.11-Based Multi-Channel Wireless Mesh Network. Proceedings of IEEE Infocom.
[3] J Jubin, JD Tornow. 1987. The DARPA packet radio network protocols. Proceedings of the IEEE.

This entry was posted on Monday, April 2nd, 2007 at 12:01 am and is filed under ProjectWM. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.