Random access channel access and backoff mechanism

• US 6,721,281 B1
• Filed: 06/14/2000
• Issued: 04/13/2004
• Est. Priority Date: 06/18/1999
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Zeira, Eldad, Dick, Stephen G.
• Primary Examiner(s): HO, DUC CHI
• Application Number:
  US09/593,879
• Time in Patent Office: 1,399 Days
• Field of Search: 370/252, 370/328, 370/335, 370/320, 370/342, 370/431, 370/443, 370/448, 370/462, 714/748, 714/749, 455/464, 455/69, 455/434, 455/450, 455/577, 455/522, 375/141
• US Class Current: 370/252
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A base station transmits access control signals on a periodic basis having a first transmission rate. The base station transmits access control modification signals at a second transmission rate higher than the first transmission rate. The user equipment transmits an access attempt signal. The access attempt signal requests the base station to permit the user equipment access to the random access channel. The user equipment receives the transmitted access control signals and access modification signals. A wait period is determined based on in part the received access control signals and access control modification signals. In response to an unsuccessful access attempt, the user equipment delays transmitting a subsequent access attempt signal for the wait period.

Claims

1. A method for controlling user equipment access to a random access channel in a wireless code division multiple access communication system, the method comprising:

transmitting on a periodic basis having a first transmission rate from a base station access control signals;

transmitting from the base station access control modification signals at a second transmission rate higher than the first transmission rate;

transmitting from the user equipment an access attempt signal, the access attempt signal requesting the base station to permit the user equipment access to the random access channel;

receiving at the user equipment the transmitted access control signals and access control modification signals;

determining a wait period based on in part the received access control signals and access control modification signals; and

in response to an unsuccessful access attempt to the random access channel, the user equipment delays transmitting a subsequent access attempt signal for the wait period.

2. The method of claim 1 wherein the access control modification signals are layer one signals.

3. The method of claim 1 further comprising:

in response to receiving the transmitted access attempt signal, the base station determining whether the user equipment is permitted to access the random access channel;

if a result of the determination is to permit access, transmitting from the base station an acknowledgment signal;

if the result of the determination is to not permit access, transmitting from the base station a negative acknowledgment signal; and

wherein an unsuccessful access attempt comprises receiving at the user equipment the negative acknowledgment signal.

4. The method of claim 3 wherein the step of the access attempt signal transmitting comprises repeatedly transmitting the access attempt signal from the user equipment for a maximum number of repetitions at increasing transmission power levels and an unsuccessful access attempt further comprises not receiving at the user equipment the acknowledgment or negative acknowledgment signal.

5. The method of claim 1 wherein the access control signals comprise backoff parameters and the wait period is a backoff wait period which is based on in part the received backoff parameters modified by the received modification signals.

6. The method of claim 1 wherein the wait period is based on in part a backoff wait period and a probability of sending an access signal during the backoff wait period.

7. The method of claim 6 wherein the access control signals comprise backoff parameters and persistence parameters and the backoff wait period is based on in part the received backoff parameters modified by the received modification signals.

8. The method of claim 6 wherein the access control signals comprise backoff parameters and persistence parameters and the sending access signal probability is based on in part the received persistence parameters modified by the received modification signals.

9. A wireless code division multiple access communication system comprising:

a base station having;

means for transmitting on a period basis having a first transmission rate access control signals; and

means for transmitting access control modification signals at a second transmission rate higher than the first transmission rate; and

a user equipment having;

means for transmitting an access attempt signal, the access attempt signal requesting the base station to permit the user equipment access to a random access channel;

means for receiving the transmitted access control signals and access control modification signals;

means for determining a wait period based on in part the received access control signals and access control modification signals; and

means for delaying transmission of a subsequent access attempt signal for the wait period in response to an unsuccessful access attempt to the random access channel.

10. The system of claim 9 wherein the access control modification signals are layer one signals.

11. The system of claim 9 wherein:

the base station further comprises;

means for determining whether the user equipment is permitted to access the random access channel, in response to receiving the transmitted access attempt signal;

means for transmitting an acknowledgment signal, if a result of the determination is to permit access;

means for transmitting a negative acknowledgment signal, if a result of the determination is to not permit access; and

the user equipment further comprises;

means for receiving an acknowledgment and a negative acknowledgment signal; and

wherein an unsuccessful access attempt comprises receiving at the user equipment the negative acknowledgment signal.

12. The system of claim 9 wherein the access control signals comprise backoff parameters and the wait period is a backoff wait period which is based on in part the received backoff parameters modified by the received modification signals.

13. The system of claim 9 wherein the wait period is based on in part a backoff wait period and a probability of sending an access signal during the backoff wait period.

14. The system of claim 13 wherein the access control signals comprise backoff parameters and persistence parameters and the backoff wait period is based on in part the received backoff parameters modified by the received modification signals.

15. The system of claim 13 wherein the access control signals comprise backoff parameters and persistence parameters and the sending access signal probability is based on in part the received persistence parameters modified by the received modification signals.