Initialization of communication channel between a subsciber station and a base station in a subscriber communication system

• US 4,811,420 A
• Filed: 07/08/1987
• Issued: 03/07/1989
• Est. Priority Date: 07/08/1987
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: International Mobile Machines Corporation (InterDigital, Inc.)
• Inventors: Avis, Graham M., Fletcher, Thomas E., Saffee, Gregory T.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Queen, Tyrone
• Application Number:
  US07/070,970
• Time in Patent Office: 608 Days
• Field of Search: 340/825.54, 455/32, 455/34, 455/51, 379/63
• US Class Current: 455/502
• CPC Class Codes: H04B 7/24 for communication between two or more posts wireless communication networks H04W
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

A subscriber communication system includes a base station in a network with a plurality of subscriber stations, wherein control information is communicated between the base station and the subscriber stations over a radio control channel (RCC) at a frequency selected by the base station from a plurality of predetermined frequencies. The a base station transmits control messages including a unique network number over the RCC. Each subscriber station processes the network number in the control message received over the RCC to enable the subscriber station to process the control message in accordance with whether the subscriber station is in the same network as the base station. The timing of communications transmitted by a subscriber station over a given communication channel between a base station and the subscriber station is refined upon initial establishment of the communication channel. Both DC signaling information and voice data signals are communicated over an assigned channel between a line appearance that couples a base station to a central office and a line interface that couples a subscriber station to a subscriber terminal.

Claims

1. A subscriber communication system, including a plurality of base stations, each in a separate network, the base station in each network being in selective communication with a plurality of subscriber stations and having means to transmit control information to its subscriber stations over a radio control channel (RCC) at a frequency selected by the base station from a plurality of predetermined frequencies;

each base station including means for transmitting over the RCC both control messages to the subscriber stations in its network and a network number unique to that base station; and

each subscriber station in each network including means for receiving the network number from any base station in the system over its respective RCC to enable that subscriber station to determine whether it is in the same network as a particular base station having a particular network number.

2. A system according to claim 1,

wherein each subscriber station includes means for searching for the RCC frequency by sequentially transmitting an RCC acquisition message at each of the predetermined frequencies, with each of the acquisition messages including an identification number that is unique to the subscriber station;

and

wherein the base station includes

means for processing the subscriber identification number in a said acquisition message received over the RCC to determine whether the subscriber station is in the same network as the base station; and

means for transmitting an acknowledgement to the subscriber station that the RCC has been acquired by the subscriber station when said processing of the subscriber identification number indicates that the subscriber station is in the same network as the base station.

3. A subscriber communication system including a plurality of base stations, each in a separate network, the base station in each network being in selective communication with a plurality of subscriber stations and having means to transmit control information to its subscriber stations over a radio control channel (RCC) at a frequency selected by the base station from a plurality of predetermined frequencies

each base station, including

a master clock for providing a system timing signal;

and

each subscriber station including

an internal timing generator for generating a subscriber station timing signal for timing the signals that are transmitted over a given communication channel from each subscriber station to a base station; and

means for providing a refinement signal timed by the subscriber station timing signal;

means operable upon initial establishment of a communication channel between a base station and a subscriber station for transmitting the refinement signal over the respective communication channel from the subscriber station to the base station;

wherein each base station further includes

means for processing the refinement signal received from a subscriber station in relation to the system timing signal to determine the value of any offset between the timing of the system timing signal and the timing of the refinement signal;

means for communicating the determined offset value to the subscriber station; and

wherein the subscriber station further includes

means coupled to the internal timing generator for processing the offset value communicated from the base station to adjust the subscriber station timing signal to reduce said offset.

4. A communication system according to claim 3,

wherein the subscriber station refinement signal transmitting means transmits successive frames of refinement signal bursts;

wherein the base station processing means determines an offset value for each received refinement signal burst; and

wherein the subscriber station processing means processes a predetermined number of successively received offset values to adjust the timing of the subscriber station timing signal.

5. A subscriber communication system according to claim 4, wherein each base station includes means for terminating communication of said predetermined offset values when a predetermined number of successively determined offset values are below a predetermined value.

6. A subscriber communication system according to claim 5,

wherein the base station communicating means communicates a stop refinement signal to the subscriber station when a predetermined number of successively determined offset values are below a predetermined value;

and

wherein the subscriber station refinement signal transmitting means responds to receipt of the stop refinement signal by ceasing to transmit the refinement signal.

7. A subscriber communication system according to claim 6,

wherein the subscriber station responds to receipt of the stop refinement signal by enabling normal communications over the given communication channel at the subscriber station.

8. A subscriber communication system according to claim 4, wherein the base station includes means for tearing down the given communication channel when said determined offset values remain above a predetermined value for a predetermined duration.

9. A subscriber communication system according to claim 8,

wherein the base station communicating means communicates an abort signal to the subscriber station when said determined offset values remain above the predetermined value for a predetermined duration;

wherein the subscriber station responds to receipt of the abort signal by sending an acknowledgment signal to the base station and by tearing down the given communication channel at the subscriber station; and

wherein the base station responds to receipt of the acknowledgment signal by tearing down the given communication channel at the base station.

10. A subscriber communication system according to claim 4, wherein the subscriber station processing means computes a mean offset value from the predetermined number of processed offset values and provides the computed mean offset value to adjust the subscriber station internal timing signal generator when the predetermined number of processed offset values are within a predetermined tolerance of the computed mean offset value.

11. A subscriber communication system according to claim 10, wherein the subscriber station processing means provides the computed means offset value to adjust the subscriber station internal timing signal generator after a predetermined duration when the predetermined number of processed offset values are not within the predetermined tolerance of the computed mean offset value.

12. A subscriber communication system including a plurality of base stations, each in a separate network, the base station in each network being in selective communication with a plurality of subscriber stations and having means to transmit control information to its subscriber stations over a radio control channel (BCC) at a frequency selected by the base station from a plurality of predetermined frequencies wherein voice data signals are communicated over an assigned channel between a line appearance that couples a base station to a central office and a line interface that couples a subscriber station to a subscriber terminal, at a base station,

each base station being coupled to a line appearance for providing an assigned channel for communicating voice data signals between the line appearance and a subscriber station;

each subscriber station being coupled to a line interface for providing an assigned channel for communicating voice data signals between the line interface and the base station; and

means for processing DC signaling information for communication over the assigned channel between the line appearance and the line interface.

13. A system according to claim 12, wherein the processing means comprise

means for detecting DC signaling information on the line appearance and/or on the line interface;

means for conditioning the detected DC signaling information for communication over the assigned channel in lieu of the voice data signals.

14. A system according to claim 13, wherein the voice data signals are communicated over the assigned channel in signal bursts;

wherein the means for detecting the DC signaling information on the line interface comprises

means in the subscriber station for monitoring signals on the line interface;

means in the subscriber station for buffering the monitored signals; and

means in the subscriber station for processing the buffered signals to detect DC signaling information; and

wherein the means for conditioning the detected DC signaling information comprises

means in the subscriber station for transmitting the detected DC signaling information over the assigned channel as a control block in a control-signal burst having the same format as a said voice-data-signal burst.

15. A system according to claim 14, wherein the control block includes a flag pattern identifying the block as a control block and further includes the DC signaling information;

and

wherein the base station further comprises

means for determining the presence of a control block in a signal burst received from the subscriber station over the assigned channel by recognizing the flag pattern; and

means responsive to recognition of the flag pattern for reformatting the the DC signaling information in the control block to a standard DC signaling information format for transfer to the line appearance.

16. A system according to claim 13, wherein the voice data signals are communicated over the assigned channel in signal bursts;

wherein the means for detecting the DC signaling information on the line appearance comprises

means in the base station for monitoring signals on the line appearance;

means in the base station for buffering the monitored signals; and

means in the base station for processing the buffered signals to detect DC signaling information; and

wherein the means for conditioning the detected DC signaling information comprises

means in the base station for transmitting the detected DC signaling information over the assigned channel to the subscriber station as a control block in a control-signal burst having the same format as a said voice-data-signal burst.

17. A system according to claim 16, wherein the control block includes a flag pattern identifying the block as a control block and further includes the DC signaling information;

and

wherein the subscriber station further comprises

means for determining the presence of a control block in a signal block received from the base station over the assigned channel by recognizing the flag pattern; and

means responsive to recognition of the flag pattern for reformatting the the DC signaling information in the control block to a standard DC signaling information format for transfer to the line interface.