Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Reexamination Certificate
1999-05-04
2004-02-03
Cangialosi, Salvatore (Department: 2661)
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
C370S219000
Reexamination Certificate
active
06687217
ABSTRACT:
TECHNICAL FIELD
This invention relates to radio systems, and more particularly, to wireless communication apparatus and systems incorporating such apparatus providing a 1:1 facility protection.
BACKGROUND
The reliability of modern electronic devices has steadily improved as has our dependence on those devices. However, while highly reliable, these devices are not immune from failure resulting from a host of predictable and unpredictable causes and events. Various techniques are used to address the failures inevitable in all systems, and particularly in mission-critical apparatus and systems. For example, certain apparatus and systems incorporate built-in test (BIT) facilities and/or built-in test equipment (BITE) to evaluate apparatus performance, identify impending and actual failures and performance degradation conditions, and isolate, reconfigure and/or bypass around failed or malfunctioning equipment. Such systems may additionally notify appropriate personnel to take corrective action to restore system performance and facilities.
Reliability is a particularly critical issue in communications systems which support multiple users. Failure of a network component at a critical node in a network may disable all communications along the network or severely impede or limit communications along or between segments of the network. Even if a graceful degradation plan is in effect, such failures often limit available bandwidth supported by the remaining network facilities that are still in operation.
One common way to address equipment failures is to provide redundancy on, for example, a 1:1 or 1:n protection basis at the equipment level at communication nodes. For example, a 1:1 or 1:n module protection scheme uses redundant circuit packs within a radio, switching to a standby pack upon detecting failure of an active circuit.
In a “cold” standby configuration, the replacement circuit is not powered until fault detection. Cold standby saves power, wear on the standby and associated circuitry, and the addition of support circuitry required to maintain the redundant standby circuitry in a power-up mode, e.g., additional power supply capacity output terminations such as dummy loads, control circuitry, cooling, etc. Conversely, cold standby requires more time to bring the replacement “on-line” and risks that the replacement may be inoperative when powered up. Alternatively, the redundant circuitry may be maintained in a “hot” standby condition so that it can be quickly and automatically substituted for the failed circuit pack or module. To further expedite this transition, the hot standby can be operated in lock-step or an “errorless” condition so that it works in parallel and synchronously with the operational unit which it backs up. A monitor system can then detect the failure and switch over to the backup unit so that the transition is virtually errorless and transparent to system users.
At a system level, these protection systems may require auxiliary processing equipment to monitor the operational equipment, identify and locate faults, and command appropriate actions to activate and substitute backup equipment for failed units. This means that the redundancy equipment must interface with the equipment being monitored, requires deployment of additional systems, and can create another failure opportunity to bring the system down. Using discrete redundancy control systems also means that additional spares must be kept on hand, increasing costs and complicating logistics.
Accordingly, a need exists for a communication system having high reliability and self-diagnostics. A further need exists for a communication system which automatically reconfigures to replace failed units and maintain network service. A further need exists for communication equipment which incorporates facilities to accomplish network reconfiguration without requiring auxiliary equipment.
SUMMARY OF THE INVENTION
The present invention is directed to wireless communication equipment, preferably microwave radio (i.e., 1 GHz and above) equipment, and systems incorporating such equipment, including a method of operating such equipment and systems, which incorporates and integrates built-in test facilities into each radio which, when integrated into a wireless link, such as those of a radio network shown and described in the above referenced patent application entitled “COMMERCIAL NETWORK BASED ON POINT TO POINT RADIOS”, automatically form a system level fault detection and isolation facility. A preferred embodiment of the invention provides built-in test and redundancy control functionality into each active and standby radio in the form of redundancy modules which cooperate to identify faults, reconfigure to replace failed radios, communicate with the rest of the network to identify failed radios in remote nodes, and notify maintenance facilities that a failure has occurred. Preferably, each redundancy module includes a set of rules for identifying and locating failures occurring at the radio module unit, mated radio pair, node and system levels. According to the preferred embodiment, since each redundancy module implements the same rule set and redundancy processing, radio replacement is easily accomplished.
According to one object of the invention, a protection switching method and apparatus is provided wherein the processing to identify a fault and provide appropriate corrective action is incorporated within a radio and is preferably provided within each radio. Further, no auxiliary or external system is required for functioning of the system other than a passive coupler to provide simultaneous inputs to and outputs from the redundant radio pair. Thus, no external control logic is required.
According to one aspect of the invention, minimal network disruption is caused during a changeover by using a hot standby redundancy.
According to another aspect of the invention, a radio communication device, preferably a transceiver although receiver and transmitter circuitry may be utilized discreetly according to the present invention, for use as one of a pair of redundant communication devices forms part of a first communication site. The first communication site is in radio communication with a second communication site of the communication system. The radio communication device, described here with reference to a transceiver embodiment to facilitate discretion of both receive and transmit redundancy, preferably includes a radio transmitter selectively operating in an active and standby mode of operation and a radio receiver. According to a feature of the invention, the radio receiver is also operative in either standby or active modes of operation. The radio transceiver further includes a receiver monitor which is responsive to the radio receiver to detect a failure of a transmitter of a pair of remote transceivers located at the second communication site. The radio transceiver also includes a controller which controls the radio transmitter to operate in the active and standby modes of operation in response to the pair of remote transceivers detecting a failure of one of the pair of redundant radio transceivers. The controller is also responsive to the receiver monitor and to a similar signal received from a receiver monitor of the other radio transceiver of the pair of redundant radio transceivers so as to supply a transmitter failure signal to the remote pair of radio transceivers located at the second communication site. Accordingly, the controller preferably includes facilities for detecting a local transmitter failure in response to a remote site's loss of signal and to identify a local receiver failure in response to only one of the local receivers experiencing a loss of signal. Conversely, the controller provides a remote transmitter failure signal in response to a loss of received signal by both local receivers.
According to a feature of the invention, a preferred embodiment radio receiver or transceiver includes an output for selectively providing a signal from the radio receiver in response to (i) a receiver m
Chow Peter El Kwan
Van Truong Jeff Keit
Cangialosi Salvatore
Carriercomm, Inc.
Fulbright & Jaworski L.L.P.
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