Hybrid return gate system in a bidirectional cable network

• US 5,867,764 A
• Filed: 11/01/1996
• Issued: 02/02/1999
• Est. Priority Date: 09/01/1995
• Status: Expired due to Term

• Current Assignee: Cable Television Laboratories Incorporated
• Original Assignee: Cable Television Laboratories Incorporated
• Inventors: Williams, Thomas H.
• Primary Examiner(s): GRANT, CHRISTOPHER C
• Application Number:
  US08/742,452
• Time in Patent Office: 823 Days
• Field of Search: 348/12, 348/10, 348/11, 348/13, 348/7, 455/5.1, 455/4.2, 455/3.1, 455/6.1, 455/6.2, 455/6.3
• US Class Current: 725/125
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/44 Star or tree networks
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A bi-directional cable network having a hybrid return gate system that prevents undesirable energy in the bi-directional cable network'"'"'s return path from adversely effecting the entire network whether the network is operating as a contention based network, a reservation based network, or combination of contention and reservation. The hybrid return gate system comprises a solid state radio frequency switch used to connect and disconnect the return path of a bi-directional communication path in conjunction with a transmission from one of a plurality of remote points. Transmissions from a remote point occur in one of a plurality of dynamically defined contention time slots or reservation time slots. At least one network monitoring time slot can also defined to monitor and/or test the bi-directional cable network. In one embodiment each return gate services a plurality of remote points downstream from the return gate. In a second embodiment each remote point has a dedicated return gate. In either embodiment, the switch in a return gate will connect the return path at the occurrence of a contention time slot accompanied by a return gate enabling prybar signal from a transmitting remote point. A return gate will also connect the return path at the occurrence of a reservation time slot assigned by the headend or due to any other command from the headend.

Claims

1. A hybrid return gate system for suppressing undesirable energy in a network having a bi-directional communication path comprising a first direction and a second direction between a headend and a plurality of remote points, said system comprising:

means for disconnecting said second direction of said bi-directional communication path;

first means for connecting said second direction of said bi-directional communication path on occurrence of at least one reservation time slot that is dynamically assigned by a command from said headend in response to a reservation time slot request submitted by any one of said plurality of remote points; and

second means for connecting said second direction of said bi-directional communication path on a contention basis in response to a request from any one of said plurality of remote points.

2. A system according to claim 1 including:

a return gate in said second direction of said bi-directional communication path shared by said means for disconnecting, said first means for connecting, and said second means for connecting.

3. A system according to claim 2 including:

a plurality of return gates in said second direction of said bi-directional communication path; and

at least one of said plurality of return gates dedicated to a corresponding one of said plurality of remote points.

4. A system according to claim 2 including:

a plurality of return gates in said second direction of said bi-directional communication path;

at least one of said plurality of return gates dedicated to a corresponding one of said plurality of remote points within one of a plurality of distribution branches in said network; and

at least one of said plurality of return gates dedicated to one of said plurality of distribution branches in said network.

5. A system according to claim 2 including:

a plurality of return gates in said second direction of said bi-directional communication path;

at least one of said plurality of return gates in a primary position dedicated to one of a plurality of distribution branches in said network; and

at least one of said plurality of return gates in a secondary position dedicated to at least one of said plurality of distribution branches in said network.

6. A system according to claim 1 including:

means for dynamically defining a series of cyclically reoccurring time slots selected from at least one of the group consisting of;

at least one contention time slot, at least one reservation time slot, and at least one network time slot; and

means for broadcasting information about said series of cyclically reoccurring time slots to facilitate transmitting in said second direction of said bi-directional communication path.

7. A system according to claim 1 including:

third means for connecting said second direction of said bi-directional communication path exclusively with said first means for connecting.

8. A system according to claim 1 including:

third means for connecting said second direction of said bi-directional communication path exclusively with said second means for connecting.

9. A system according to claim 1 wherein said first means for connecting includes:

means for transmitting said reservation time slot request in a contention time slot in said second direction by a requesting one of said plurality of remote points means

means for receiving a reservation time slot assignment from said headend by said requesting one of said plurality of remote points and a return gate device controlling said second direction on behalf of said requesting one of said plurality of remote points; and

means for transmitting a data packet in said reservation time slot assignment in said second direction by said requesting one of said plurality of remote points in conjunction with said return gate device connecting said second direction of said bi-directional communication path for a duration of said reservation time slot assignment.

10. A system according to claim 9 including:

means for accompanying said data packet in said reservation time slot assignment with a request for at least one additional reservation time slot assignment for said requesting one of said plurality of remote points.

11. A system according to claim 1 wherein said second means for connecting includes:

means for generating a gate enabling prybar signal by a transmitting one of said plurality of remote points;

means for transmitting a data packet in a contention time slot substantially concurrently with said gate enabling prybar signal in said second direction of said bi-directional communication path from said transmitting one of said plurality of remote points;

means for receiving said gate enabling prybar signal in a return gate device capable of connecting said second direction of said bi-directional communication path;

means for connecting said second direction of said bi-directional communication path by said return gate device in response to said gate enabling prybar signal to allow said data packet to pass through said return gate device; and

means for disconnecting said second direction at an end of said contention time slot.

12. A hybrid method for suppressing undesirable energy in a network having a first direction and a second direction in a bi-directional communication path between a headend and a plurality of remote points, said method comprising:

disconnecting said second direction of said bi-directional communication path;

first step of connecting said second direction of said bi-directional communication path on occurrence of at least one reservation time slot dynamically assigned by a command from said headend in response to a reservation time slot request submitted by any one of said plurality of remote points; and

second step of connecting said second direction of said bi-directional communication path on a contention basis in response to a command from any one of said plurality of remote points.

13. A method according to claim 12 including:

dynamically defining a series of reoccurring time slots selected from at least one of a group consisting of;

at least one contention time slot and at least one reservation time slot; and

broadcasting said series of reoccurring time slots for transmissions in said second direction of said bi-directional communication path.

14. A method according to claim 12 wherein said first step of connecting includes:

a first set of steps comprising;

transmitting a reservation time slot request in a contention time slot by a requesting one of said plurality of remote points;

receiving a reservation time slot assignment from said headend by said requesting one of said plurality of remote points; and

transmitting a data packet in said reservation time slot assignment by said requesting one of said plurality of remote points;

a second set of steps occurring in concert with said first set of steps, comprising;

detecting said reservation time slot request in said headend from said requesting one of said plurality of remote points; and

broadcasting said reservation time slot assignment in said first direction from said headend across said network;

a third set of steps occurring in concert with said first set of steps and said second set of steps, comprising;

monitoring said first direction of said bi-directional communication path with a return gate device;

detecting said reservation time slot assignment in said first direction with said return gate device; and

connecting said second direction of said bi-directional communication path with said return gate device at an occurrence of said reservation time slot assignment for a duration of said reservation time slot assignment.

15. A method according to claim 14 including:

accompanying said data packet in said reservation time slot assignment with a request for at least one additional reservation time slot.

16. A method according to claim 12 wherein said second step of connecting includes:

a first set of steps comprising;

generating a gate enabling prybar signal by a transmitting one of said plurality of remote points;

transmitting a data packet in a contention time slot substantially concurrently with said gate enabling prybar signal on said second direction of said bi-directional communication path from said transmitting one of said plurality of remote points;

determining if said data packet was successfully transmitted on said second direction of said bi-directional communication path; and

retransmitting said data packet if said data packet did not transmit successfully on said second direction of said bi-directional communication path;

a second set of steps occurring in concert with said first set of steps, comprising;

detecting said return gate enabling prybar signal in said second direction of said bi-directional communication path; and

connecting said second direction of said bi-directional communication path for a duration of said contention time slot.

17. A method according to claim 12 including:

operating said second direction of said bi-directional communication path on a contention access only basis according to said second step of connecting said second direction.

18. A method according to claim 12 including:

operating said second direction of said bi-directional communication path on a reservation access only basis according to said first step of connecting said second direction.

19. A return gate system for suppressing undesirable energy in a network having a first direction and a second direction in a bi-directional communication path between a headend and a plurality of remote points, said system comprising:

means for dynamically defining a series of reoccurring time slots selected from at least one of the group consisting of;

at least one contention time slot and at least one reservation time slot;

means for restricting a transmission of a signal in said second direction of said bi-directional communication path comprising;

means for transmitting a reservation time slot assignment in said first direction of said bi-directional communication path from said headend to said plurality of remote points;

means for transmitting said signal in said second direction in a reservation time slot assigned to one of said plurality of remote points by said headend;

first means for connecting said second direction of said bi-directional communication path in response to an occurrence of said reservation time slot assigned to one of said plurality of remote points that resides in a part of said network controlled by said first means for connecting;

means for disconnecting said second direction of said bi-directional communication path at an end of said reservation time slot;

second means for connecting said second direction of said bi-directional communication path in response to a return gate enabling signal in said second direction of said bi-directional communication path transmitted by a remote point that resides in a part of said network controlled by said second means for connecting; and

means for disconnecting said second direction of said bi-directional communication path at an end of said occurrence of said contention time slot.

20. A return gate system according to claim 19 wherein said means for dynamically defining includes:

means for defining at least one contention only time slot; and

means for operating said network with contention only network communications in said second direction of said bi-directional communication path.

21. A return gate system according to claim 19 wherein said means for dynamically defining includes:

means for defining at least one reservation request contention time slot;

means for defining at least one reservation time slot; and

means for operating said network with reservation only network communications in said second direction of said bi-directional communication path.