Multiplex communications – Fault recovery – Bypass an inoperative channel
Reexamination Certificate
1998-05-05
2002-01-15
Chin, Wellington (Department: 2664)
Multiplex communications
Fault recovery
Bypass an inoperative channel
C370S315000, C370S350000
Reexamination Certificate
active
06339585
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to error recovery methodology in communication systems, and, in particular, to a method of error-recovery which utilizes the establishment of a temporary forwarding node through which information can be advantageously forwarded during periods when the communication link between a primary station and a wireless terminal is disabled or less than satisfactory. The establishment of the temporary forwarded node ensures that the wireless terminal and/or primary base station continuously receives the transmitted information transmitted by the other source. The present invention relates to the method of use of the temporary forwarding node in both a centralized architecture and an adhoc architecture as well as the system configurations contemplated thereby.
The success of various telecommunication systems, such as GSM, establish wireless communications as indispensable in modern life. While certain systems are directed only to voice communications, the future communications content is multimedia in nature. ATM (asynchronous transfer mode) technology has been developed over wired networks to deal with high-speed data with, for example, different data rates, different quality-of-service (Qos) requirements (such as data reliability and delay considerations) and different connection or connectionless paradigms for multimedia communications. An effective combination of wireless and ATM-based service at the consumer end of a wired network will be instrumental in establishing a large multimedia home and business communications market.
Existing efforts towards building a wireless local-area network (LAN) are focused around emerging standards, such as IEEE 802.11 (United States) and HIPERLAN (Europe). While the standards are almost mature, their development do not adequately take into consideration ATM-based service requirements of QoS guarantees for both real-time and data traffic. Essentially these requirements are the result of complex video, audio, and data service multiplexing in the same medium. For example, while audio data does not require the packet-error reliability required of data services, audio data cannot tolerate excessive delay. On the other hand, video data can in general suffer more delay than audio, although, it is less tolerant to delay jitter. These delay and packet-error rate considerations forced ATM to adopt a connection-oriented service. It also forced error-control to be performed end-to-end, instead of between every two nodes within the specified connection (error-control being understood to mean a method of ensuring reliable transmission of packets to and from a node). Such a strategy was feasible with the wired fiber-optic networks, which has a very small packet error rate. Unfortunately, wireless networks do not in general provide such low-error rates.
Delay considerations are also important for ATM service. A wired ATM network will simply block any services for which it cannot guarantee the required QoS. Typically wireless networks do not allow such a feature and the delay actually can increase exponentially in an overloaded network.
Accordingly, an improved communication system which overcomes the aforementioned deficiencies, and in particular, reduces the packet-error rate, reduces the transmission delay, and at the same time increases the quality of service guarantees, improves reliability in communication and improves error-recovery, is desired.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, forward-error-correction (FEC) techniques can be used to determine drastic falls in performance if the total signal power at a wireless terminal is less than a predetermined value. This can then allow for the channel to be considered to be in either “good” or “bad” states. Of course, since the channel does not change very fast, it is expected that whenever there is a transition between the “good” and the “bad” states, it will remain in either state for considerable amount of time relative to the transmission rate of the system. If the channel goes in the “bad” state, the preferable solution is to change the channel. Utilizing this approach, the present invention contemplates the utilization of a temporary forwarding node to reroute the information from a sender to the receiver.
Specifically, a method of transmitting information in a communications system is provided. The method preferably comprises the steps of establishing a first communications link between a first base station and a second base station, attempting to establish or satisfactorily maintain a second communication link between the first base station and the wireless terminal and upon a determination that the second communication link cannot be established or satisfactorily maintained, transmitting information from the first base station to the second base station for retransmission of the information to the wireless terminal, attempting to reestablish the second communication link between the first base station and the wireless terminal and upon such establishment, discontinuing the transmission of subsequent information from the first base station to the second base station and directly transmitting the subsequent information to the wireless terminal from the first base station.
In another preferred embodiment, the method of transmitting information in a communications system comprises the steps of establishing a first communications link between a first node and a second node, establishing a second communications link between the first node and the wireless terminal, transmitting information from the wireless terminal to both the first and second nodes, the information being received by both the first and second nodes, transmitting the information from the second node to the first node, processing, in the first node, the information first received by the wireless terminal or the second node and discarding the second receipt of the information from the other of the wireless terminal or the second node.
The method of transmitting information in a communications system may also comprise the steps of establishing a communications link between a primary node and a secondary node, determining that a communications link between the primary node and the wireless terminal is unsatisfactory for reliable information transmission, transmitting information from the primary node to the secondary node for retransmission to the wireless terminal, transmitting information from the wireless terminal to the secondary node for retransmission to the primary node during which the primary node is attempting to establish a communications link with the wireless terminal, achieving establishment of the communications link between the primary node and the wireless terminal, and disabling the communications link between the secondary node and the wireless terminal.
Additionally, the present invention is directed to a communication system that can carry out the foregoing methods.
Accordingly, it is an object of the present invention to provide an improved method to more reliably relay data and/or signaling information.
Another object of the present invention is to provide a method of improving reliable data or signaling information transmission using a temporary forwarding node which may advantageously be another base station operating on preferably the same frequency, or could be another wireless terminal.
Yet another object of the present invention is to provide a method of improved reliable communication with the automatic detection of a faulty communication link with a wireless terminal.
Still another object of the present invention is to provide a method of improving reliable communication which can utilize multiple temporary forwarding nodes.
And still yet another object of the present invention is to provide a method of improving reliable data communication that can also be realized in a stationary environment such as in a residential or office building environment.
And still yet another object of the present invention is to p
Hulyalkar Samir N.
Ngo Chiu Y.
Verma Dinesh C.
Chin Wellington
Harper Kevin C.
Philips Electronics North America Corp.
Piotrowski Daniel J.
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