Packet interface and method of packetizing information

• US 6,747,977 B1
• Filed: 11/09/1999
• Issued: 06/08/2004
• Est. Priority Date: 06/30/1999
• Status: Expired due to Fees

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Tsang, Fai, Brueckheimer, Simon Daniel, Smith, Roger
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): HYUN, SOON D
• Application Number:
  US09/437,063
• Time in Patent Office: 1,673 Days
• Field of Search: 370/473, 370/474, 370/395.1, 370/395.6, 370/395.61, 370/395.64, 370/466, 370/470, 370/471, 370/392, 370/393, 370/401, 370/465, 370/468, 370/476
• US Class Current: 370/395.64
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/5654 using the AAL1
• CPC Class Codes: H04L 2012/5664 Support of Video, e.g. MPEG
• CPC Class Codes: H04L 2012/5667 IP over ATM
• CPC Class Codes: H04L 2012/5671 Support of voice

Abstract

To obviate inefficient use of bandwidth in a packetised system, such as a broadband ATM domain, the use or amount of header information sent in relation to a channel is restricted by one of two principal mechanisms, as exemplified in FIGS. 3 and 4. First, control information incident to a packet interface (20) is interrogated by a processor (21) to determine (50) packet length requirements. A packet length indicator is then generated (52) for inclusion within a header (44) of a packet. Alternatively, a frame (30) is pre-partitioned (60) into several packets (32-42) having different lengths. An addressed subscriber unit (28) is allocated (64) a particular channel, i.e. at least one particular packet within the frame (30), based on data throughput requirements (62), whereby the location of the packet within the frame inherently identifies the length of the packet. Optionally, the data rate used within that packet may also be identified inherently by the location of the packet within the frame (30).

Claims

1. A method of sending information in packets over a multiplicity of frames, the method comprising:

pre-partitioning each frame into a plurality of slots of which at least one has a differing duration to the others, each of the plurality of slots being associated with at least a respective defined packet length and a channel; and

packetising call information into a slot of a pre-partitioned frame allocated to a call for transmission of said call information to an addressed unit, the packetised call information containing a truncated header of reduced length arising from the slot allocated to the call inherently identifying the defined packet length thereof and the channel through said slot'"'"'s association with a respective defined packet length and a channel for said slot in said pre-partitioned frame.

2. The method according to claim 1, wherein the frames are each pre-partitioned in an identical fashion.

3. The method according to claim 1, wherein a slot assigned to the call is identical between contiguous frames.

4. The method according to claim 1, wherein a slot assigned to the call is varied between contiguous frames according to a predetermined sequence.

5. The method according to claim 1, wherein the packet is a non-standard sized ATM packet in a broadband domain, and where conversion between the broadband domain and a narrowband domain occurs.

6. The method according to claim 1, wherein a slot position is identified relative to a fixed timing structure.

7. The method according to claim 1, further comprising assessing at least one of a data transmission requirement for the call and a processing capability of an addressed unit of the call before allocating the slot.

8. The method according to claim 1, further comprising notifying the addressed subscriber unit of the slot allocated to the call.

12. The method according to claim 1, comprising:

receiving information from a channel and constructing at least one intermediate packet associated with that channel during a first time segment;

generating an intermediate packet header having an intermediate packet length indication identifying a number of intermediate bytes received from the channel within the first time segment;

communicating the intermediate packet header and the at least one intermediate packet to a broadband signal processor;

receiving the intermediate packet header at the broadband signal processor and interrogating the intermediate packet header to identify the number of intermediate bytes that can be expected at the broadband signal processor during a second time segment;

determining whether the at least one intermediate packet to be received at the broadband signal processor should be temporarily stored or converted into a broadband packet for onward transmission; and

generating a broadband packet including a header containing a length indication if the at least one intermediate packet is to be converted into a broadband packet for substantially instantaneous onward transmission, else temporarily storing the at least one intermediate packet and incrementing a record of a number of intermediate packets temporarily stored in relation to said channel.

13. The method of sending information in packets according to claim 12, wherein the length indication in the broadband packet is variable and dependent upon the number of intermediate packets that are to be transmitted in the broadband packet.

14. The method of sending information in packets according to claim 12, further comprising repeatedly storing contiguous intermediate packets incident on the broadband signal processor during successive time segments and incrementing the record of the number intermediate packets temporarily stored in relation to said channel.

15. The method of sending information in packets according to claim 14, further comprising:

comparing the record of the number of intermediate packets with a predetermined threshold and constructing a broadband packet and associated length indicating when the record of the number of intermediate packets is at least equal to the predetermined threshold.

16. The method of sending information in packets according to claim 12, wherein the step of temporarily storing the intermediate packets is overridden on the basis of one of an addressing unit'"'"'s identity and an addressed unit'"'"'s identity.

9. A packet interface for coupling between a narrowband domain and a broadband domain, the packet interface arranged to packetise information from the narrowband domain to the broadband domain into variable length packets, the packet interface having associated therewith:

a processor arranged to construct a plurality of contiguous frames with each frame pre-partitioned into a plurality of slots of which at least one has a differing duration to the others, each of the plurality of slots being associated with at least a respective defined packet length and a channel, the processor further comprising;

means to packetise call information from the narrowband domain into a slot of a pre-partitioned frame selectively allocated to a call for transmission of said call information to an addressed unit, the packetised call information containing a truncated header of reduced length arising from the slot allocated to the call inherently identifying the defined packet length thereof and the channel through said slot'"'"'s association with a respective defined packet length and a channel for said slot in said pre-partitioned frame.

10. The packet interface according to claim 9, wherein the processor further comprises:

means to assess at last one of a data transmission requirement for the call and a subscriber processing capability of the addressed unit in the call; and

means to select and allocate the slot within the frame based on the assessment.

11. The packet interface according to claim 9, wherein the processor further comprising means for notifying the addressed unit of the slot allocated to the call.

17. A packet interface according to claim 9, comprising:

a) a first buffer and processor combination arranged to receive information form a channel and to construct intermediate packets associated with that channel during a first time segment, the processor including;

means for generating an intermediate packet header having an intermediate packet length indication identifying a number of intermediate bytes received from the channel within the first time segment; and

means for communicating the intermediate packet header and the intermediate packets to a broadband signal processor;

b) a signal processor and channel buffer combination, the signal processor coupled to received the intermediate packet header and arranged to interrogate the intermediate packet header to identify the number of intermediate bytes that can be expected at the broadband signal processor during a second time segment, the signal processor further comprising;

means for determining whether the intermediate packet to be received should be temporarily stored or converted into a broadband packet for onward transmission; and

means for generating a broadband packet including a header containing a length indication if an incident intermediate packet is to be converted into a broadband packet for substantially instantaneous onward transmission, else means for temporarily storing the incident intermediate packet in the channel buffer and incrementing a record of a number of intermediate packet temporarily stored in relation to said channel.

18. The packet interface according to claim 17, wherein the length indication in the broadband packet is variable and dependent upon the number of intermediate packets that are to be transmitted in the broadband packet.

19. The packet interface according to claim 17, wherein the signal processor and channel buffer are further arranged to repeatedly store contiguous intermediate packets incident on the broadband signal processor during successive time segments and wherein the signal processor further includes means for incrementing the record of the number intermediate packets temporarily stored in relation to said channel.

20. The packet interface according to claim 17, wherein the signal processor further comprises:

means for comparing the record of the number of intermediate packets with a predetermined threshold; and

means for constructing a broadband packet and associated length indication when the record of the number of intermediate packets is at least equal to the predetermined threshold.

21. The packet interface according to claim 17, wherein the signal processor is arranged to override the temporarily storing of the intermediate packets on the basis of one of an addressing unit'"'"'s identity and an addressed unit'"'"'s identity.

22. A communications network comprising:

a broadband communications network;

a narrowband communications network; and

a packet interface for coupling said broadband and narrowband communications networks, the packet interface being arranged to packetise information from the narrowband domain to the broadband domain into variable length packets, the packet interface having associated therewith;

a processor arranged to construct a plurality of contiguous frames with each frame pre-partitioned into a plurality of slots of which at least one has a differing durations to the others, each of the plurality of slots being associated with at least a respective defined packet length and a channel, the processor further comprising;

means to packetise call information from the narrowband domain into a slot of a pre-partitioned frame selectively allocated to a call for transmission of said call information to an addressed unit, the packetised call information containing a truncated header of reduced length arising from the slot allocated to the call inherently identifying the defined packet length thereof and the channel through said slot'"'"'s association with a respective defined packet length and a channel for said slot in said pre-partitioned frame.