WIRELESS NETWORK
OVERVIEW:
A wireless networks consists of two major parts:

Access point - A network bridge between the wireless network and the wired LAN. The access point allows hosts on the wireless network to communicate to hosts on the wired network.

Host computer with a network antenna - Normally a laptop computer with a network antenna attached to a PCMCIA card.

CONSIDERATIONS:
When designing the wireless network you must be concerned with the following issues:

Network Issues

Coverage

Interference from other devices

Security of data on network

Interoperability of wireless equipment

Network Design

Overlapping Cells

Wired to/from Wireless communication

Moble vs Roaming Communication

Mobility Limitations

Network Protocols : Unicast vs Multicast Communication

OUR DECISION:
After extensively researching various wireless network options and vendors, we decided to use Lucent's WaveLAN equipment. The WaveLAN technology currently operates at 2 Mbps which is share by all laptops using the network. Latency between machines is slightly higher than latencies experience across a standard ethernet, but for most applications the difference is not noticable at all. Lucent is expected to release a 10 Mbps version of their equipment within the next year. You can purchase 915 Mhz or 2.4 Ghz equipment with the 915 giving you a little better distance but the 2.4 giving you a little less interference with cell phones, etc. We chose the 2.4 Ghz because it provide almost the same indoor coverage in our environment as the 915. The equipment we purchased did not yet follow the IEEE wireless standard, but their new equipment does and should be able to interoperate with other vendors.

One advantage of the WaveLAN access points is that they are easily upgraded. Each access point can hold two standard PCMCIA wireless NIC cards which is how they communicate with the other wireless laptops roaming about. If you really want to get higher bandwidth, you can play little tricks by inserting two cards and running them at different frequencies to double the effective bandwidth of the cell covered by the access point. However, this means half the machines must be configured on one frequency while the others are configured for the other frequency. The access points function just like a standard bridge, allow you to filter certain packet types, and support roaming (i.e., laptops can move from one access point to the other without loss of communication). We found the access points to be very robust. We have put pretty heavy loads on them (including live video and audio multicasts) yet they have been running since they were installed without need for any physical access to them and only occassional network access to modify the filters. Lucent technical support has been very good.

In short, we have been very happy with the Lucent equipment, but in light of the recent IEEE standard, most vendors should interoperate.

LINKS:
Here is a good link for information on mobile IP and Linux.

Links to wireless network vendors: