The proxim wireless ethernet cards arrived on Monday, May 2nd. The
two main competitors to the rangeLAN2 technology are Xircom's netwave
and NCR's wavelan. Although we already have Mach drivers for the
wavelan hardware, the wavelan PCMCIA model requires more transmit,
receive, and standby power compared to rangeLAN2. We wanted to
purchase hardware that could work with a low power PDA. Xircom's
netwave hardware is a first generation product and they were not
considering to release a device driver development kit until next
year. Proxim was the only company that had a second generation
wireless ethernet product and was willing to release a device
driver development kit.
Software Details
Negotiations for a non-disclosure agreement with Proxim are in the
works. By May 13th we can either return the hardware for a full
refund, but I expect to have a NDA agreement worked out with Dean
Chang @ Proxim. Upon delivery of the C level development kit I'll
start to implement a driver for Mach 3.0.
Delivered with the rangeLAN2 cards were binaries of the ODI/NDIS
drivers. I'll try to run the ODI driver between my office (Sieg 223)
and Geoff Voelker's office (Sieg 225). The
distance between the two workstations is about 20ft separated by a
thin wall. We'll measure signal strength and link quality
using the utilities provided by Proxim.
Hardware Details
Specifications
- Bus Interface: ISA BUS
- Range: up to 500ft
- Data Rate: 1.6Mbps (uncompressed)
- Media Access Protocol: RangeLAN2 CSMA/CA
- Ethernet Compatibility: Ethernet packet types and ethernet addressing
- Frequency Band: 2.4-2.483 Ghz (spread spectrum frequency hopping).
- Independent Channels: 15
- Output Power: 100 mW
Frequency Hopping
The rangeLAN2 uses a spread spectrum frequency hopping technique.
This means that the radio signal is constantly moving from one
frequency to anther in a pre-defined sequence. For two rangeLAN2
radios to communicate, they must be at the same frequency at the same
time. The rangeLAN2 cards can be configured as a master, alternative
master, or a station. All stations look to the master to determine
where and when to hop to a new frequency. If there is no master
station present, a station configured as an alternative master will
decide to become the master for that session. Can someone explain
what spread spectrum is?
Network Configuration
Mobile units should be configured as alternative stations. While they
are in the reach of a basestation (master) all mobile units will
synchronize their frequency hopping with the master. When there is no
master station then the mobile units will come to a consensus about a
new master. It is unclear if the consensus is controlled by the
device driver or by the firmware. Proxim's user manual mentions that
the highest performance is achieved when the fewest number of machines
possible are configured as master or alternative master stations.
Signal Strength
The hardware supports a mechanism to measure both the link quality and
signal strengths of other rangeLAN2 devices.
Security
The rangeLAN2 supports a security ID and every card must have a
matching ID in order to communicate. The security ID prevents
unauthorized access to the departmental networks via wireless
ethernet. This logical security probably is better than the simple
physical security that we have now with our current ethernet. At the
moment it is possible for anyone to walk up to an ethernet transceiver
and gain full network connectivity.
Microwave Ovens
Both the rangeLAN2 radios and microwave ovens operate in the same
frequency band. We'll probably notice some network performance
degradation when both are operated in close vicinity. The output
power is 100 mW versus 400-800 W used by microwave ovens;
nevertheless, it is a disturbing thought that I'll be microwaving
myself slowly.
Silly PC details
- IRQ = 3,4,5,7,10,11,12,15
- I/O Address = 100,120,140,218,270,280,290,298,2A0,2A8,2E0,300,310,358,360,368
Marc E. Fiuczynski
$Id: proxim_progress.html,v 1.5 1994/05/04 18:19:14 mef Exp $