1. Technical Field
The present invention relates generally to wireless communication systems and more particularly to a wireless communication system having noise management circuitry operable to reduce generated noise during receipt of a radio communication. The present invention also relates to transmission protocols and operating modes in a wireless communication system that allow units within the system to selectively operate in reduced noise modes when required.
2. Related Art
Wireless communication systems are well known in the art. In most wireless systems, control units form the basis of a communication cell. The control units act as hubs in facilitating communication with and between terminal units in the cell and also often provide a communication link between the wireless communication system and a wired communication system. Terminal units may include hand-held data terminals, code readers, printers, portable computers and various other devices that require communication with other devices in the system. Thus, portable units within the wireless communication system may easily communicate with other wireless units in the system as well as with units connected only to the wired communication system
Modern wireless communication systems operate using various transmission techniques that were developed to increase both the speed and accuracy of the transmissions within the system. Some of these techniques, such as frequency hopping, include modifying the frequency of operation of the radios within the system to avoid noisy portions of the transmission spectrum. Other of these techniques, such as code spreading, include encoding and decoding transmissions within the system to increase the likelihood of receiving correct data. In the operation of many wireless systems, however, control units transmitting data and terminal units receiving data are isolated from one another and the strength of received signals is relatively small. Transmitter strength, the physical distance between control unit and the terminal unit, the existence and type of physical obstacles between the units, background noise and various other factors affect the quality and strength of received transmissions. Problems caused by these factors cannot be fully addressed by known techniques.
With the advent of high speed digital circuitry, another communication problem has arisen. Control and terminal units have circuitry that operates at high clocking frequencies. Digital signals produced by the circuitry travel along buses and other conductors within the units and produce radiated noise. Because of the physical proximity between the circuitry and the radios in the units, the radios receive the radiated noise while concurrently receiving wireless communications. The locally generated noise interferes with receipt of the communications and oftentimes requires that data transmission rates be decreased and/or that data corrupted by the noise be re-transmitted.
Shielding of the circuitry within the units does not fully block the radiated noise and adds cost to the units. Further, the modular construction of many units precludes proper shielding.
Thus, there is a need in the art for a wireless communication system that produces minimal generated noise during receipt of wireless communications that may corrupt the communications.
There is a further need in the art for a wireless communication system that operates in various reduced noise modes but that still performing required processing functions.
Thus, it is an object of the present innovation to provide a wireless communication system that selectively operates in a noise reduced state during the receipt of wireless communications.
It is a further object of the present invention to provide a wireless communication system that selectively operates in various noise reduced states based upon its own characteristics as well as the wireless transmission characteristics of the system.
It is still a further object of the present invention to provide a wireless communication system that allows control units and terminal units to cooperatively operate in various modes as required to facilitate satisfactory communications.