System and method for optimizing spectral efficiency using time-frequency-code slicing

• US 6,064,662 A
• Filed: 09/14/1998
• Issued: 05/16/2000
• Est. Priority Date: 04/28/1994
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Gitlin, Richard D., Karol, Mark J., Woodworth, Clark, Haas, Zygmunt
• Primary Examiner(s): VU, HUY DUY
• Application Number:
  US09/154,403
• Time in Patent Office: 610 Days
• Field of Search: 370/330, 370/329, 370/436, 370/437, 370/478, 370/468, 370/479, 370/335, 370/336, 370/337, 370/342, 370/343, 370/345, 370/431, 370/441, 370/442, 370/465, 370/480, 370/498 , 370/535, 370/477, 375/200, 375/201, 375/202, 375/203, 375/204, 375/205, 375/206
• US Class Current: 370/330
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04J 4/00 Combined time-division and frequency-division multiplex systems H04J13/00 takes precedence ; data transmission H04L5/26; telemetry G08C15/00
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 72/0466 the resource being a scrambling code

Abstract

A system and method for optimizing usage of a communications transmission medium. The transmission medium may be sliced into time and frequency domains so as to create time-frequency slices for assignment to users having varying access rates and user-application requirements. Through scheduling of the various speed users within the frequency and time domains, the system and method can efficiently allocate and make use of the available spectrum, thereby accommodating higher rate users requiring greater bandwidths and time slot assignments while still preserving cost-efficient access for lower speed users. Depending on the signal modulation scheme, the time-frequency slices may be allocated on non-contiguous frequency bands. The system and method is also applicable to code-division multiple access (CDMA) techniques by slicing the available code space along time-code domains, frequency-code domains or, in three dimensions, along time-frequency-code domains. Users may be efficiently scheduled based on code space requirements so as to optimize user of the communication medium.

Claims

1. A system for optimizing spectral user of a code-division-multiple-access (CDMA) transmission medium by a plurality of users of varying user-application and access rates, comprising:

a plurality of code slice allocations collectively representing a quantity of code space contained in said transmission medium;

a plurality of time slices in said transmission medium;

means for slicing the transmission medium into a plurality of code-time slices; and

means for scheduling one or more users in at least one of said code-time slices in said transmission medium, wherein said means for scheduling schedules a quantity of code space based on a level of interference contributed by each user in said transmission medium, the scheduling based on a number and type of users for each of said code-time slices.

2. The system in accordance with claim 1, wherein a signal transmitted by a user in said transmission medium is assigned a quantity of code space in said transmission medium.

3. The system in accordance with claim 2, wherein said quantity of code space is inversely related to the length of code assigned to a user.

4. A system for optimizing spectral use of a code-division-multiple-access (CDMA) transmission medium by a plurality of users of varying user-application and access speeds, comprising:

a plurality of code slice allocations representing a quantity of code space contained in said transmission medium;

a plurality of time slices in said transmission medium;

means for slicing the transmission medium into a plurality of code-time slices;

a set of individual codes contained within said transmission medium;

means for assigning an individual code having a length to a user of said transmission medium, the length of said individual code inversely related to a quantity of code space to be occupied by said user;

means for scheduling one or more users in at least one of said code-time slices in said transmission medium, wherein said means for scheduling assigns individual length codes to said users based on the code space requirements of the users in said transmission medium.

5. The system of claim 4, wherein at least one of said individual codes in reassigned to a user based on temporal occupancy of said at least one individual code in the transmission medium.

6. A system for optimizing spectral use of a code-division-multiple-access (CDMA) transmission medium by a plurality of users of varying user-application and access speeds, comprising:

a plurality of code slice allocations representing a quantity of code space contained in said transmission medium;

a plurality of time slices in said transmission medium;

a plurality of frequency slices in said transmission medium;

means for slicing the transmission medium into a plurality of code-time-frequency slices; and

means for scheduling one or more users in at least one of said code-time-frequency slices in said transmission medium, wherein said means for scheduling schedules a quantity of code space to each of said users of the transmission medium.

7. The system in accordance with claim 6, wherein said means for scheduling schedules users to said code-time-frequency slices based on the user-application and access rates of said users.

8. A method for optimizing spectral use of a CDMA communications transmission medium by a plurality of users of varying user-application and access rates, comprising the steps of:

slicing the transmission medium into a plurality of code slice allocations collectively representing a quantity of code space contained within said transmission medium;

slicing the transmission medium into a plurality of time-slice allocations;

slicing the transmission medium into a plurality of code-time slices, each of the code-time slices occupying space at least equal to one code slice allocation extending over one time slice allocation; and

scheduling one or more said users in at least one of said code-time slices in the transmission medium according to the amount of code space required by each of said users so as to optimize the occupancy of the code space contained within the communications transmission medium.

9. A method for optimizing spectral use of a CDMA communications transmission medium by a plurality of users of varying user-application and access rates, comprising the steps of:

slicing the transmission medium into a plurality of code slice allocations collectively representing a quantity of code space contained within said transmission medium;

slicing the transmission medium into a plurality of frequency slice allocations;

slicing the transmission medium into a plurality of code-frequency slices, each of the code-frequency slices occupying space at least equal to one code slice allocation extending over one frequency slice; and

scheduling one or more of said users in at least one of said code-frequency slices in the transmission medium according to the amount of code space required by each of said users so as to optimize the occupancy of the code space contained within the communications transmission medium.

10. A method for optimizing spectral use of a CDMA communications transmission medium by a plurality of users of varying user-application and access rates, comprising the steps of:

slicing the transmission medium into a plurality of code slice allocations collectively representing a quantity of code space contained within said transmission medium;

slicing the transmission medium into a plurality of time slices;

slicing the transmission medium into a plurality of code-time slices, each of the code-time slices occupying space at least equal to one code slice allocation extending over one time slice allocation;

assigning an individual user a code from a set of individual codes contained within said transmission medium, the length of said individual code inversely related to a quantity of code space to be occupied in the medium by said user; and

scheduling one or more of said users in at least one of said code-time slices in the transmission medium, wherein the means for scheduling assigns an individual length code to a user based on code space requirements of a user so as to optimize the occupancy of the code space contained within the communications transmission medium.

11. A method for optimizing spectral use of a code-division-multiple-access (CDMA) transmission medium by a plurality of users of varying user-application and access speeds, comprising the steps of:

slicing the transmission medium into a plurality of code slice allocations representing a quantity of code space contained in said transmission medium;

slicing the transmission medium into a plurality of time slices in said transmission medium;

slicing the transmission medium into a plurality of frequency slices in said transmission medium;

slicing the transmission medium into a plurality of code-time-frequency slices; and

scheduling one or more users in at least one of said code-time-frequency slices in said transmission medium according to the amount of code space required by each of said users so as to optimize the occupancy of the code space contained within the communications transmission medium.

12. A system for maximizing spectral use of a communications transmission medium by a plurality of users of varying user-application and access rates, comprising:

a plurality of frequency slices along a frequency dimension in said communications transmission medium;

a plurality of time slices along a time dimension in said communications transmission medium;

means for slicing the communications transmission medium into a plurality of time-frequency slices, each of said time-frequency slices occupying a space in said communications transmission medium at least equal to one frequency slice allocation measured over one time slice allocation; and

means for scheduling said users in a plurality of time-frequency slice so as to maximize the use of said communications transmission medium along both said time and frequency dimensions, wherein at least one of said users modulates a respective transmitted signal over two or more frequency slice allocations in said communications transmission medium, wherein said at least one of said users occupies two or more time-frequency slices extending over two or more frequency slice allocations in said communications transmission medium, wherein said two or more time-frequency slices do not form a continuous allocation.

13. A system for maximizing spectral use of a communications transmission medium by a plurality of users of varying user-application and access rates, comprising:

a plurality of frequency slices in said communications transmission medium;

a plurality of time slices in said communications transmission medium;

means for slicing the communications transmission medium into a plurality of time-frequency slices occupying a space in said communications transmission medium equal to at least one frequency slice allocation measured over one time slice allocation, wherein at least one of said users modulates his respective signal to cover two or more frequency slice allocations in said communications transmission medium; and

means for scheduling a plurality of users in a plurality of said time-frequency slices so as to maximize the use of said communication transmission medium, wherein said at least one user modulates his respective signal on a multi-tone scheme, wherein each of the tones modulated by said user is allocated to a separate frequency slice, wherein said frequency slice allocation are not contiguous.

14. A method for maximizing spectral use of a communications transmission medium by a plurality of users of varying user-application and access rates, comprising the steps of:

dividing the transmission medium into a plurality of frequency slices;

dividing the transmission medium into a plurality of time slices;

slicing the transmission medium into a plurality of time-frequency slices;

occupying space at least equal to one frequency slice extending over one time slice;

modulating the signal emitted by a user over two or more frequency slices; and

scheduling a plurality of users in a plurality of said time-frequency slices so as to maximize the use of the space contained within said communications transmission medium which includes the substep of scheduling two or more time frequency slices having non-contiguous frequency slice allocations.