Method and apparatus enabling multiple access on a broadband communication network

• US 6,813,277 B2
• Filed: 12/26/2001
• Issued: 11/02/2004
• Est. Priority Date: 04/15/1998
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Sriram, Kotikalapudi, Li, Chia-Chang, Edmon, Eugene L.
• Primary Examiner(s): TON, DANG T
• Application Number:
  US10/036,272
• Publication Number:
  US 20020057709A1
• Time in Patent Office: 1,042 Days
• Field of Search: 370/442, 370/347, 370/321, 370/337, 370/351, 370/352, 370/401, 370/465, 370/470, 370/461, 370/462, 370/457, 370/458, 370/459, 370/460, 370/468, 370/345.1, 370/251, 370/252, 370/254, 370/395.61, 370/395.63, 370/395.65, 370/395.64, 370/395.42, 370/395.43, 370/395.5, 370/395.41, 370/395.21, 370/396
• US Class Current: 370/442
• CPC Class Codes: H04J 3/1694 Allocation of channels in TDM/TDMA networks, e.g. distributed multiplexers Passive Optical Networks H04Q11/0062
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 2012/5671 Support of voice
• CPC Class Codes: H04L 2012/5675 Timeslot assignment, e.g. TDMA
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A protocol for handling multiple access on broadband communication networks, e.g., fiber/coax networks and wireless networks, supports both continuous bit rate (CBR) and variable bit rate (VBR) traffic representing voice, video telephony, interactive television, and data. The invention is carried out both in customer premise equipment (CPE) at stations, and in a common controller with which all stations communicate. A medium access control (MAC) processor provided in each of the stations and in the common controller divides the time domain for a given RF channel into a series of successive frames, each having a plurality of time slots. Because of the architecture of the communication network, individual stations do not communicate directly with each other, but can receive broadcast messages indicating the status of each time slot, which messages are generated in the common controller and transmitted in a downstream channel. When a station desires to transmit information in the upstream direction, it inserts the information into an available time slot, with availability being determined in accordance with time slot status. Depending upon the type of traffic being originated, a station can indicate to the common controller a need for continued use of the “same” time slot in successive frames. This permits a station, such as a station requiring a CBR connection, to avoid having to contend repeatedly for continued access to the transmission network. In the case of a wireless communication network, the invention is carried out both in mobile stations, and in a base station which acts as a common controller and with which all mobile stations communicate.

Claims

1. A method of allocating transmission bandwidth among a plurality of stations interconnected with a common controller via a transmission medium having a multiple access upstream channel, said method comprising the steps of:

dividing data in said upstream channel on said transmission medium into a series of successive time frames;

dividing each of the time frames into a plurality of time slots wherein said time slots consist of both fixed length and variable length time slots;

responsive to contention by competing stations of said plurality of stations requiring transmission bandwidth, allocating, on an initial basis, one or more of said plurality of time slots to a particular station of said plurality of stations that contends for said plurality of time slots;

reserving said one or more of said plurality of time slots for continued use by said particular station in response to a reservation indication contained in a plurality of messages inserted by said particular station in said one or more of said plurality of time slots;

providing a plurality of status messages in said one or more of said plurality of time slots indicative of a status of each of said one or more of said plurality of time slots to said plurality of stations from said common controller, the plurality of status messages provided in said plurality of time slots including overhead information; and

combining contiguous time slots of the plurality of time slots to form a super slot, if said contiguous time slots are allocated to a particular station of said plurality of stations, by eliminating the overhead information contained in at least one of said contiguous time slots.

2. The method defined in claim 1, wherein a first subset of said plurality of stations each originate constant bit rate (CBR) traffic requiring a first number of time slots per time frame, a second subset of said plurality of stations each originate CBR traffic requiring a second number of time slots per time frame, and wherein said first and second numbers are different.

3. The method defined in claim 1, wherein a first subset of said plurality of stations each originate constant bit rate (CBR) traffic requiring a fixed number of time slots per time frame and a second subset of said plurality of stations each originate variable bit rate (VBR) traffic requiring a variable number of time slots per time frame.

4. The method defined in claim 1, wherein said method further includes the steps of:

providing said plurality of status messages in a downstream channel; and

responsive to said plurality of status messages, said plurality of stations (a) transmitting a new packet in one of said plurality of time slots, (b) continuing to transmit an on-going message in one of said plurality of time slots, or (c) allowing other ones of said plurality of stations to transmit in one of said plurality of time slots.

5. A method of allocating transmission bandwidth among a plurality of stations interconnected with a common controller via a transmission medium having a multiple access upstream channel, at least one of said plurality of stations originating variable bit rate (VBR) traffic, said method comprising:

dividing data in said upstream channel on said transmission medium into a series of successive time frames;

dividing each of the time frames into a plurality of time slots;

allocating a guaranteed minimum number of time slots of said plurality of time slots to at least one station of said plurality of stations, on an initial basis, when said at least one station contends for said plurality of time slots;

allocating said guaranteed minimum number of time slots for continued use by said at least one station in response to a first reservation indication contained in a first plurality of messages inserted by said at least one station in said guaranteed minimum number of time slots, wherein the first plurality of messages inserted into said guaranteed minimum number of time slots include first overhead information;

allocating a plurality of additional time slots of said plurality of time slots to said at least one station when the at least one station signals a high activity period,

allocating said plurality of additional time slots for continued use by said at least one station during said high activity period, in response to a second reservation indication contained in a second plurality of messages inserted by said at least one station in said plurality of additional time slots;

wherein the second plurality of messages inserted into said plurality of additional time slots include second overhead information;

releasing said plurality of additional time slots when the at least one station signals a decrease in its activity; and

wherein, if more than one of said guaranteed minimum number of time slots and said plurality of additional time slots is allocated to a particular station, said method further includes the steps of;

determining if said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots are contiguous; and

combining said guaranteed minimum number of time slots and said plurality of additional time slots into a superslot if said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots are contiguous, by eliminating the overhead information contained in at least one of said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots.

6. A method of allocating transmission bandwidth among a plurality of stations interconnected with a common controller via a transmission medium having a multiple access upstream channel, said method comprising the steps of:

dividing time in said upstream channel on said transmission medium into a series of successive time frames;

dividing each of the time frames into a plurality of time slots wherein said time slots consist of both fixed length and variable length time slots;

providing a plurality of status messages indicative of a status of each of said plurality of time slots to said plurality of stations from said common controller, said plurality of status messages being provided in a downstream channel;

responsive to said plurality of status messages, said plurality of stations(a) transmitting a new packet in one of said plurality of time slots, (b) continuing to transmit an on-going message in one of said plurality of time slots, or (c) allowing other ones of said plurality of stations to transmit in one of said time slots; and

wherein each of said plurality of status messages is provided to said plurality of stations in a time slot of said plurality of time slots in said downstream channel that occurs at a time interval before an appearance of a corresponding time slot of the plurality of time slots in a next succeeding time frame in the series of successive time frames in said upstream channel.

7. The method defined in claim 6, wherein said time interval is sufficiently long so as to permit said plurality of stations to process and respond to said plurality of status messages.

8. A method for allowing a plurality of stations originating constant bit rate (CBR) and variable bit rate (VBR) types of traffic to share a transmission medium having a multiple access upstream channel to a common controller, said upstream channel including a series of successive time frames, and each time frame including a plurality of time slots, said method comprising the steps of:

determining the type of traffic to be transmitted by a station seeking access to the transmission medium,

for CBR traffic, allocating, on an initial basis, one or more of said plurality of time slots to a first station of said plurality of stations that contends for said plurality of time slots; and

reserving said one or more of said plurality of time slots for continued use by said first station in response to a first reservation indication contained in a first plurality of messages inserted by said first station in said one or more of said plurality of time slots; and

for VBR traffic, allocating a guaranteed minimum number of time slots of said plurality of time slots to a second station of said plurality of stations, on an initial basis, when said second station contends for said plurality of time slots;

reserving said guaranteed minimum number of time slots for continued use by said second station in response to a second reservation indication contained in a second plurality of messages inserted by said second station in said guaranteed minimum number of time slots;

allocating a plurality additional time slots of said plurality of time slots to said second station when the second station signals a high activity period;

reserving said plurality of additional time slots for continued use by said second station during said high activity period, in response to a third reservation indication contained in a third plurality of messages inserted by said second station in said plurality of additional time slots;

releasing said plurality of additional time slots when the second station signals a decrease in its activity, and

wherein, if more than one of said guaranteed minimum number of time slots and said plurality of additional time slots is allocated to a particular station, said method further includes the steps of;

determining if said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots are contiguous; and

combining said guaranteed minimum number of time slots and said plurality of additional time slots into a superslot, if said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots are contiguous, by eliminating overhead information contained in at least one of said more than one of said guaranteed minimum number of time slots and said plurality of additional time slots.

9. The method defined in claim 8, wherein said transmission medium further includes a downstream channel, and wherein said method further includes the steps of:

providing a plurality of status messages indicative of a status of each of said plurality of time slots to said plurality of stations, said plurality of status messages being provided in said downstream channel; and

responsive to said plurality of status messages, said plurality of stations (a) transmit a new packet in one of said plurality of time slots, (b) continue to transmit an ongoing message in one of said plurality of time slots, or (c) allow other ones of said plurality of stations to transmit in said one of said plurality of time slots.

10. A communication system, including:

a transmission network, wherein a plurality of stations are interconnected with a common controller via a transmission medium having a multiple access upstream channel and a broadcast downstream channel, each of said upstream and downstream channels defining a sequence of time frames, each of the time frames including a plurality of time slots, and

means for allowing any of said plurality of stations requiring isochronous, asynchronous or sporadic transmission capacity to transmit signals in any available time slots of the plurality of time slots on said upstream channel without interfering with each other, wherein the means for allowing includes;

means in said common controller for transmitting status information regarding the plurality of time slots in said upstream channel to said plurality of stations, said status information being transmitted in said downstream channel;

means in said plurality of stations for receiving said status information and in response, interpreting and creating a control signal indicating whether to transmit or not;

means in said plurality of stations arranged so that, if said plurality of stations transmit data in one or more of said plurality of time slots in said upstream channel, said plurality of stations include an indication of sustained use of said one or more of said plurality of timeslots in subsequent time frames in the sequence of time frames; and

means in the plurality of stations for inserting in a particular subset of the plurality of time slots, a first indication to said common controller of an intention of a particular station to combine a plurality of messages in a contiguous series of time slots of the plurality of time slots in a time frame in the sequence of time frames.

11. A communication system, including:

a transmission network, wherein a plurality of stations are interconnected with a common controller via a transmission medium having a multiple access upstream channel and a broadcast downstream channel, each of said upstream and downstream channels defining a sequence of time frames, each of the time frames including a plurality of time slots,

means in the plurality of stations for inserting in a particular subset of the plurality of time slots, a first indication to said common controller of an intention of a particular station to combine a plurality of messages in a contiguous series of time slots of the plurality of time slots in a time frame in the sequence of time frames, and a second indication to said common controller of an intention of said particular station to use a particular time slot in a particular subsequence of time frames in the sequence of time frames.

12. The system of claim 11, wherein said plurality of messages includes overhead information, and wherein said combining means includes means for forming a superslot by eliminating said overhead information contained in said plurality of messages in said contiguous time slots of theplurality of time slots.

13. The system defined in claim 12, wherein said overhead information includes a guard time and a preamble, and wherein said combining means is arranged to eliminate the guard time and preamble normally found between at least two adjacent time slots of the plurality of time slots.

14. A method of providing shared access to a plurality of time slots on a transmission medium interconnecting a plurality of stations to a common controller via a tree and branch arrangement, comprising the steps of:

generating in said plurality of stations an indication for said common controller of a type of traffic being generated in said plurality of stations, said type of traffic including isochronous, asynchronous or sporadic traffic;

responsive to said indication of the type of traffic, generating in a head end a signal for providing each station of the plurality of stations with necessary bandwidth by (a) dynamically allocating a number of time slots of the plurality of time slots assigned to said each station in each time frame, and (b) reserving those time slots of the plurality of time slots in a plurality of successive time frames assigned to contain information associated with said each station; and

modifying an allocated number of time slots of the plurality of time slots for a particular station of the plurality of stations in accordance with a look ahead prediction of a need for additional bandwidth by that particular station.

15. The method defined in claim 14, wherein said common controller is further arranged to generate a plurality of status messages for upstream time slots of the plurality of time slots and transmit said status plurality of messages in a downstream channel, said plurality of status messages reflecting the allocations of said plurality of time slots.

16. The method defined in claim 15, wherein each station seeking access for sporadic traffic is arranged to transmit in a time slot of the plurality of time slots that is not yet allocated and is thus available for contention.

17. The method defined in claim 15, wherein each station transmitting asynchronous traffic is further arranged to obtain additional bandwidth needed to transmit additional information by transmitting in other available time slots of the plurality of time slots on a contention basis.

18. The method defined in claim 16, further including the step of preassigning, in said common controller, one or more time slots of the plurality of time slots for use solely by a portion of the sporadic traffic generated in said each station, based upon a priority of said portion of the sporadic traffic.

19. An apparatus for allocating transmission bandwidth among a plurality of stations interconnected with a common controller via a transmission medium having a multiple access upstream channel, said apparatus comprising:

means for (a) dividing data in said upstream channel on said transmission medium into a series of successive time frames and (b) dividing each of the time frames into a plurality of time slots;

means for providing a plurality of status messages indicative of a status of each of said plurality of time slots to said plurality of stations from said common controller, said plurality of status messages being provided in a downstream channel;

means in said plurality of stations, responsive to said plurality of status messages, for (a) transmitting a new packet in one of said time slots, (b) continuing to transmit an on-going message in one of said time slots, or (c) allowing other ones of said stations to transmit in said one of said time slots; and

means for combining contiguous time slots of the plurality of time slots, if said contiguous time slots are allocated to a particular station of said plurality of stations, by eliminating overhead information contained in at least one of said contiguous time slots.

20. A method of allocating transmission bandwidth among a plurality of stations, said method comprising:

combining contiguous time slots of a plurality of time slots, if said contiguous time slots are allocated to a particular station of said plurality of stations, by eliminating overhead information contained in at least one of said contiguous time slots.

21. The method of claim 20, wherein the plurality of stations are interconnected with a common controller via a transmission medium having a multiple access upstream channel.

22. A method for allowing a plurality of stations originating constant bit rate (CBR) and variable bit rate (VBR) types of traffic to share a transmission medium having a multiple access upstream channel to a common controller, said upstream channel including a series of successive time frames, and each time frame including a plurality of time slots, said method comprising the steps of:

combining one or more guaranteed time slots of the plurality of time slots and one or more additional time slots of the plurality of time slots into a superslot, if said one or more guaranteed time slots and said one or more additional time slots are contiguous and allocated to the same station of the plurality of stations, by eliminating overhead information contained in at least one of said plurality of guaranteed time slots and said plurality of additional time slots.