Frequency coordination

Abstract: An improved AMPS cellular system where non-interfering digital communication channels are added to the existing analog or digital voice communications channels in the system by utilizing frequency space between channels made possible by the AMPS co-channel and adjacent channel frequency coordination procedures. Interference is prevented by reduction of power, selection of frequencies, proper modulation and demodulation techniques, and unique allocation to the channels in frequency and location. The system is also applicable in general to the insertion of narrow frequency bandwidth channels in any existing communications system using co-channel and adjacent channel frequency allocation strategies.

Abstract: A broadband local area data network uses coaxial cable wiring for interconnection of terminal devices. Orthogonal frequency division multiplexing (OFDM) with bit loading is used to overcome channel impairments and provide a path for terminal devices to transmit to and receive from other terminal devices. Probe messages are sent between devices to characterize the communication channel and determine optimum bit loading. The data network shares the cable spectrum with other services and uses frequency bands not used by other services. Adaptive power control can be used to maintain signal to noise ratio in a communication between terminal devices. Frequency coordination can be used to avoid interference between the LAN communications and other services transmitted on the cable.

Abstract: Recently, the current technology, WLAN a data communication device receiving worldwide attention, is operated on a 2.4 GHz ISM band. But since the ISM band is an unlicensed band used in a variety of low-power devices, there is a concern about radio interference between systems using the ISM band. With regard to this, IEEE 802.15 TG2 is operated on the basis of frequency coordination considering the radio interference between WLAN and Bluetooth [http:www.ieee802.org/15/pub/TG2.html]. However, there is insufficient research on the radio interference between WLAN and other radio devices. Therefore, in this paper, we explain the results of experiments conducted on the radio interference between the WLAN and other radio devices operated on a 2.4 GHz ISM band. Radio interference experiments were performed on the microwave oven which is easy to come across in our everyday living; the plasma lighting system (PLS), which is installed in hotels and other common places; and the video transmission device used in the wireless remote control robot for detecting explosives, which is operated in the airport, a hot spot area of WLAN. The results of the experiments will be utilized as data for more effective operation of WLAN.

Abstract: Unlike radio and microwave systems, Free Space Optics (FSO) is an optical technology which requires no spectrum licensing or frequency coordination with other users and provides secure transmission because of negligible interception by using point-to-point laser signals in conjunction with low errors than that of optical fiber transmission. This paper is an endeavor to thrash out about internal and external parameters that degrade the performance of FSO systems in conjunction with the alleviation techniques to realize a high speed, bandwidth efficient long haul FSO transmission system.