Multiplex communications – Channel assignment techniques – Adaptive selection of channel assignment technique
Reexamination Certificate
1999-07-02
2001-04-24
Rao, Seema S. (Department: 2661)
Multiplex communications
Channel assignment techniques
Adaptive selection of channel assignment technique
C370S228000, C370S439000, C370S449000, C370S462000, C370S465000, C370S522000, C379S230000
Reexamination Certificate
active
06222849
ABSTRACT:
BACKGROUND
The present invention relates generally to designating a control channel in a telecommunications system.
Telecommunications terminals connect subscriber lines, such as POTS (Plain Old Telephone Service) lines, ISDN (Integrated Services Digital Network) lines, E1 (Electronic Interface Level 1) lines, and optics lines to telecommunications exchanges and other telecommunications equipment. A terminal contains channel unit card slots that accept channel unit cards. The channel unit cards, or line cards, convert analog or digital signals from subscriber lines into formatted digital data signals. Different types of channel unit cards service different types of subscriber lines.
A terminal constructs a single time division multiplexed (TDM) signal from several channel unit cards' formatted digital data signals for transmission to remote telecommunications equipment. The terminal also demultiplexes TDM signals received from remote telecommunications equipment to deliver formatted digital data back to the channel unit cards. Channel unit cards convert the formatted digital data into a form suitable for transmission over subscriber lines.
Two telecommunications terminals can be connected “back to back” to form a digital carrier loop network. A digital carrier loop network typically includes a remote terminal placed near a business or residence and a central terminal placed in a central exchange connected to a telecommunications switch. The remote terminal and central terminal communicate over one or more lines carrying TDM signals. This configuration connects subscribers to the telecommunications switch.
SUMMARY
In general, in one aspect, a method of providing a control channel between first and second access terminals in a digital loop carrier, includes forming a pool of channels which couple the first and second terminals, wherein each member of the pool can be assigned either to serve as the control channel or as a data channel. A member of the pool is dynamically assigned as the control channel. The control channel can be used to convey information regarding assignment of data channels to handle an incoming or outgoing call.
In another aspect, a digital loop carrier includes terminals configured and programmed to assign a control channel dynamically from among a pool of channels.
Various implementation can include one or more of the following features. A first signal pattern can be broadcast from the first terminal to the second terminal over at least a subset of the pool members. A second signal pattern can be transmitted from the second terminal to the first terminal over a pool member on which the first signal pattern was broadcast and received. A third signal pattern can be transmitted from the first terminal to the second terminal using the pool member over which the second signal pattern was transmitted and received. The pool member, over which the second and third signal patterns were transmitted and received, can then be assigned as the control channel. The first, second and third signal patterns can include, for example, predetermined asynchronous patterns.
In some implementations, the first and second terminals are central office and remote terminals of a digital loop carrier. The pool of channels can consist of non-dedicated channels. A pool member can be assigned dynamically as the control channel in response to detection of a failure of a previously assigned control channel.
The first signal pattern can be broadcast repeatedly from the first terminal to the second terminal. Similarly, the second signal pattern can be repeatedly transmitted from the second terminal to the first terminal using the pool member on which the first signal was received by the second terminal.
The first and second terminals can include respective databases storing status information for the pool members. Thus, in some implementations, the first signal pattern can be broadcast only over those pool members whose status information indicates that they currently are not handling a call on a subscriber line, do not have an alarm associated with them, and are in service.
The second terminal can poll at least a subset of the pool members for receipt of the first signal pattern. Similarly, the first terminal can poll at least a subset of the pool members for receipt of the second signal pattern. In various implementations, the terminals poll only pool members whose status information indicates that they currently are not handling a call on a subscriber line, do not have an alarm associated with them, and are in service.
The second terminal can calculate an expected response time within which it expects to receive a third signal pattern from the first terminal on the same poll member over which the second signal pattern was transmitted. The expected response time can be calculated by multiplying the number of pool members by a predetermined average time. If the third signal pattern is not received within the expected response time, a status indicator for the pool member over which the second signal pattern was transmitted can be marked as currently unavailable.
In addition, the transmission medium can comprise, for example, one or more metallic conductors, optical fibers, wireless media or a combination thereof. Similarly, the pool of channels can be formed from among channels in the conductors, the optical fibers, wireless channels, or a combination thereof. A single channel can serve as the control channel for all the available data channels connecting the two terminals.
In some implementations, subscriber signaling information also can be communicated over the control channel.
Various implementations may provide one or more of the following advantages. By dynamically allocating the control channel from among a pool of available channels, the system provides greater flexibility in the event of the failure of a control channel or the failure of an entire facility carrying the control channel. Moreover, the technique described herein obviates the need for reserving a particular channel as a back-up control channel. A new control channel is assigned if and when it is required. Thus, a greater number of channels can be used for carrying subscriber data.
Additional features and advantages will be readily apparent from the following description, drawings and claims.
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Cornes Martin P. J.
Giordano Glenn Anthony
Koath Christopher James
Alcatel USA Sourcing L.P.
Fish & Richardson P.C.
Rao Seema S.
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