Transmission control scheme

• US 6,889,056 B2
• Filed: 04/30/2001
• Issued: 05/03/2005
• Est. Priority Date: 04/30/2001
• Status: Expired due to Term

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Shibutani, Akira
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US09/846,021
• Publication Number:
  US 20020193133A1
• Time in Patent Office: 1,464 Days
• Field of Search: 455/69, 455/126, 455/522, 455/13.1, 455/63, 455/424, 370/252
• US Class Current: 455/522
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning
• CPC Class Codes: H04W 52/267 taking into account the information rate

Abstract

The present invention provides a transmission control scheme for wireless digital networks comprised of a plurality of access points each communicating with access terminals, which improves data throughput to access terminals located in areas where interference from the neighboring access points are high. Generally, under the transmission control scheme according to the present invention, the access points are controlled so that neighboring access points will not transmit signals simultaneously with transmission parameters providing high robustness. The transmission parameters include, for instance, transmission power, a modulation scheme and a coding rate. Higher power transmission achieves higher robustness. Transmission at a lower modulation level achieves higher robustness. Transmission at a lower coding rate achieves higher robustness. Transmission providing high or low robustness will expand or narrow a virtual communication zone, which is defined in this application as an area within which it is feasible at a given level of error performance for access terminals to communicate with the access point in the zone. The access points may change their transmission parameters according to predetermined schedules, such as at regular intervals.

Claims

1. A transmission control scheme for wireless digital networks comprised of a plurality of access points communicating with access terminals, in which transmission parameters of the access points are collectively controlled so that neighboring access points will not transmit signals simultaneously with transmission parameters providing high robustness, the scheme comprising the steps of:

requesting a permission to transmit with transmission parameters achieving high robustness;

receiving a permission, wherein the permission is given with priority to an access point that has large data to be transmitted; and

while in possession of the permission, making a transmission with transmission parameters achieving high robustness.

2. A transmission control scheme as defined in claim 1, wherein the transmission parameters include any of transmission power, a modulation scheme and a coding rate.

3. A transmission control scheme for wireless digital networks comprised of a plurality of access points communicating with access terminals, in which transmission parameters of the access points are collectively controlled so that neighboring access points will not transmit signals simultaneously with transmission parameters providing high robustness, the scheme comprising the steps of:

requesting a permission to transmit with transmission parameters achieving high robustness;

receiving a permission wherein the permission is given with priority to an access point that has a large number of access terminals to serve; and

while in possession of the permission, making a transmission with transmission parameters achieving high robustness.

4. A transmission control scheme for wireless digital networks comprised of a plurality of access points communicating with access terminals, comprising the steps of:

(a) acknowledging a condition of communication channel with an access terminal that is estimated to be realized;

(b) determining a data transmission rate highest feasible at a given transmission power level under the estimated channel condition;

(c) revising the determined data transmission rate based on a length of data to be transmitted to the access terminal;

(d) revising the transmission power level to a level at which the revised data transmission rate is highest feasible; and

(e) transmitting data to the access terminal at the revised transmission rate at the revised transmission power level.

5. A transmission control scheme as defined in claim 4, further comprising the step of, in response to the revision of the transmission power level by an access point, calibrating the determined data transmission rate in view of an expected change in interference due to the revision of the power level by the neighboring access point.

6. A transmission control scheme as defined in claim 4, wherein the channel condition is realized by means of any one of SIR, SNIR, SNR, CI, FJN, FER, BER and DRC.

7. A transmission control scheme as defined in claim 4, wherein the channel condition is-measured by the access terminal.

8. An access point that wirelessly communicates with access terminals, comprising:

a transmission control that requests a permission to transmit with transmission parameters achieving high robustness so that neighboring access points will not transmit simultaneously with transmission parameters providing high robustness, the permission being given with priority to an access point that has large data to be transmitted; and

a transmitter that, while in possession of the permission, performs a data transmission with transmission parameters achieving high robustness.

9. An access point that wirelessly communicates with access terminals, comprising:

a transmission control that requests a permission to transmit with transmission parameters achieving high robustness so that neighboring access points will not transmit simultaneously with transmission parameters providing high robustness, the permission being given with priority to an access point that has a large number of access terminals to serve; and

a transmitter that, while in possession of the permission, performs a data transmission with transmission parameters achieving high robustness.

10. An access point that wirelessly communicates with an access terminal, comprising:

a channel condition detector that acknowledges an estimated condition of communication channel to be realized with the access terminal;

a transmission rate control that determines a data transmission rate highest feasible at a given transmission power level under the estimated channel condition and then revises the determined data transmission rate based on a length of data to be transmitted to the access terminal;

a transmission power control that revises the given transmission power level to a level at which the revised data transmission rate is to be highest feasible;

a transmitter that transmits data to the access terminal at the revised transmission rate at the revised transmission power level.

11. An access point as defined in claim 10, wherein the channel condition is realized by means of any one of SIR, SNIR, SNR, CI, EIN, FIER, BER and DRC.

12. An access point as defined in claim 10, wherein the channel condition is measured by the access terminal.

13. A transmission control scheme for wireless digital network comprised of a plurality of access points communicating with access terminals, comprising the steps of:

(a) acknowledging an estimated condition of communication channel to be realized with an access terminal;

(b) revising the estimated channel condition in view of a change of a transmission power level at which a neighboring access point is to perform a data transmission;

(c) determining a data transmission rate highest feasible at a given transmission power level under the revised channel condition; and

(d) transmitting to the access terminal at the determined highest transmission rate at the given transmission power level.

14. A transmission control scheme as defined in claim 13, further comprising the step of determining a power level lower than the given power level at which the determined highest transmission rate is to be still feasible wherein data is to be transmitted at the determined highest transmission rate at the determined lower power level.

15. A transmission control scheme as defined in claim 13, wherein the channel condition is realized by means of any one of SIR, SNIR, SNR, CI, E/N, FER, BER and DRC.

16. A transmission control scheme as defined in claim 13, wherein the channel condition is, measured by the access terminal.

17. An access point that wirelessly communicates with an access terminal, comprising:

a channel condition detector that acknowledges an estimated condition of communication channel to be realized with an access terminal and revises the estimated condition in view of a change of a transmission power level at which a neighboring access point is to perform a data transmission;

a transmission rate control that determines a data transmission rate highest feasible at a given transmission power level under the revised channel condition; and

a transmitter that transmits to the access terminal at the determined highest transmission rate at the given transmission power level.

18. An access point as defined in claim 17, further comprising a transmission power control that determines a power level lower than the given power level at which the determined highest transmission rate is to be still feasible, wherein the transmitter transmits to the access terminal at the determined highest transmission rate at the determined lower power level.

19. An access point as defined in claim 17, wherein the channel condition is realized the means of any one of SIR, SNIR, SNR, CI, EIN, FER, BER and DRC.

20. An access point as defined in claim 17, wherein the channel condition is measured by the access terminal.