Verizon M7100 The M7100 Internal Radio

The M7100 Internal Radio

The M7100 Handheld Terminal comes equipped with an internal 802.11b radio and antenna. This

internal radio is specifically designed to communicate with any 802.11b Access Point. The range

of the internal radio depends greatly on the quality of the Access Point and the RF

communications characteristic of the environment where the device is used. The typical range for

an 802.11b radio is 500 feet through free air. Additional Access Points must be added to improve

coverage in a larger area, or in electrically noisy RF environments.

Wireless LAN technology is designed to make maintaining a connection between two devices as

reliable and consistent as possible. Since the speed of the connection between wireless devices

will vary as range and signal quality varies, the wireless devices will intentionally sacrifice

throughput (data rate or connection speed as measured in bits per second) in exchange for

maintaining a reliable connection. In other words, a reliable connection at a lower speed is

preferred over an unreliable connection at a higher speed (i.e., it is easier to maintain the

connection if data rate is deliberately reduced, or put another way, lower data rates will tolerate a

higher range and/or worse signal quality). This characteristic is known as fallback. As example, an

802.11b system will fallback from 11 Mbps to 5.5 Mbps as range increases or signal quality

decreases. Subsequent fallbacks from 5.5 Mbps to 2 Mbps and 1 Mbps are also supported

802.11b operates in a range of radio frequencies known as an "unlicensed" band (i.e. the FCC does

NOT require the use of a license in order to operate a radio transmitter in this range). This means

that commercially available radio devices other than wireless LAN devices are permitted to use

the same frequency band as 802.11b. Consequently, these co-existing radio devices can interfere

or "jam" the wireless LAN (and vice versa). Ironically, the most troublesome devices are cordless

telephones and microwave ovens.

Fortunately, higher quality cordless phones tend to "listen" for a clear channel before becoming

active and will thus avoid interfering with a wireless LAN (i.e., the cordless phone seeks a clear

channel for itself so naturally avoids being interfered with or being a source of interference).

Jamming from microwave ovens is more severe but is usually restricted to the upper frequency

range for 802.11b (it should be noted that 802.11b divides the available frequency band into 11

channels. The higher numbered channels are most susceptible to microwave oven interference).

In each instance, jamming occurs only when the cordless telephone or microwave oven is active.

Much has been publicized in the media about security problems with wireless LANs. Although it

cannot be denied that the encryption algorithms currently used in 802.11b are flawed, the fact is

that security breaches of a wireless LAN require a deliberate attempt to access the network by an

intruder. It is highly recommended that WEP encryption be used and in some cases the access