Cisco Aironet 350 Series

This document provides information on the most frequently asked questions about wireless local-area network (WLAN) radios.

A. Some radio equipment manufacturers specifically warn against this because it damages the transmitter. Most pieces of amateur or commercial radio equipment carry this warning because they operate at a much higher transmitter power. The reflected wave standing wave ratio (SWR) caused by the lack of a proper antenna or load can damage the final amplifier stage known as the power amplifier (PA).

For Cisco Aironet equipment, the transmitter power output is 100 mW for the 350 series and 30 mW for the 340 series, so damage is unlikely but possible. If you absolutely have a requirement to run the devices without antennas, it is recommended that you turn the transmitter power down to 1-5 mW or use a 50-52 ohm "dummy load," just to be safe.

Warning: Never connect the antenna port of one device directly into the antenna port of another device since this could damage the devices.

A. In most cases, a license is not required to operate a spread spectrum device. In the United States, spread spectrum devices fall under Federal Communications Commission (FCC) Part 15 of the rules that govern unlicensed devices. However, other countries might require a license if you operate devices that are partially or completely outdoors, such as point-to-point bridges. In addition, some countries might require the system importer to obtain a telecommunications license to sell the product.

A. Under current Federal Aviation Administration (FAA) rules, the use of wireless devices on an aircraft is permitted if the aircraft is parked at the gate and the door is open, and if usage is allowed in the airport. The device must not interfere with flight operation equipment such as navigation radar, communications, or emergency services.

The use of wireless devices on an aircraft with the door closed, whether it is sitting at the gate, taxiing, or in flight, is prohibited by the FAA and other Civil Aviation Agencies worldwide. Wireless devices used on the aircraft (when the door is open at the gate) must meet the requirements of the local country agency or have been granted a waiver by the agency or airport authority.

Wireless devices that are stored on the aircraft for use at the gate must meet certification requirements for the country that the local carrier is flagged for, and must be able to operate in the frequency band of the host country, unless a waiver is granted to the system user. It is the responsibility of the system installer to obtain all licenses and frequency or usage waivers.

A. The WLAN devices are safe when used under normal operating conditions as stated in the user manuals. The power levels are below the power level of a typical microwave oven. The radio modules were tested by independent test labs in accordance with various recognized standards. The levels measured when the PCMCIA antenna was 1 cm away from the user were recorded at 10-12% of the maximum level allowed.

A. No. The FCC defines the system that uses directional gain antennas as only part of the complete system. You cannot exceed the 4W EIRP for any of the legs of this system since the whole system is a point-to-multipoint. This topic is defined in FCC docket 96-8, which covers the spread spectrum transmitter.

A. Relocate the Cisco Aironet equipment as far away as practical from potential sources of EMI/RFI or reorient the point-to-point antennas away from the RFI/EMI emitter.

Use a different frequency range for the phone and WLAN.

A. Yes. By its very nature, an FH product hops across the entire band. It therefore encounters interference from our product and causes interference to our product. There is no way to control where an FH unit hops. Blocking out the portion of the spectrum that the equipment uses is a possible solution, but in the United States the FCC does not permit FH devices to limit their hop—they must hop across the whole band.

A. 802.11b has a maximum speed of 11 Mbps while 802.11g and 802.11a have 54 Mbps.

A. A second antenna is only helpful if the signal from the first is not good enough. Even though you can connect two antennas for diversity. The AP uses only one, it checks for interface/multipath and then chooses the best choice. Also check the transmit power (by default it is set to max), unless this has been lowered.

A. A bridge is a device that connects two or more networks. The bridges can be separated with the media type they are connected with. If two networks are bridged together with wire then those are called 802.3 bridges while those which connect the network via wireless are called 802.11 bridges. Functionality-wise both are the same. Both IEEE standards have a different type of frame size. In order to communicate between them, there should be a translation of frame. Translation is usually done by the access point.

A. The extension cable between the AP 1242 and the AIR-ANT1728 antenna is AIR-CAB005LL-R. This extension cable is five feet long. The AIR-CAB005LL-R cable has the appropriate connector to connect to the AIR-ANT1728 antenna and the AP 1242.