RANDOM ACCESS CHANNEL PROTOCOL

• US 20110176506A1
• Filed: 03/30/2011
• Published: 07/21/2011
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Tong, Wen, Zhu, Peiying, Vvedenskaya, Nikita D., Fedortsov, Sergei P., Likhanov, Nikolai L.
• Granted Patent: US 8,730,936 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 12/40143 involving priority mechanisms hybrid switching fabrics H04L12/6402; intermediate storage or scheduling H04L49/90; time-division multiplex systems H04J3/00
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

The present invention provides an improved random access channel protocol, wherein different user elements may be associated with different priority levels. Based on relative priority, the user elements may have different probabilities for deciding when to retransmit a previously transmitted packet upon receiving information from an access point indicating that the packet needs to be retransmitted. A buffer is provided for storing a packet to transmit, and the buffer is associated with a stack counter, which is incremented or decremented to or from a nominal value to determine when to transmit or retransmit the packet stored in the buffer. Based on the relative priority, feedback information from the access point may cause the stack counter for a packet needing to be retransmitted to stay at the nominal value, wherein retransmission will occur at the next available time slot, or it may increase the stack counter by one or more levels.

Claims

1. A method of facilitating random access communications at an access point comprising:

a) attempting to receive a packet transmitted from at least one of a plurality of user elements during a time slot;

b) determining if a packet was properly received during the time slot;

c) transmitting a feedback message to the plurality of user elements wherein the feedback message is selected from a group comprising;

1) an idle message indicating that no transmissions were detected during the slot,

2) a successful transmission message indicating that a packet was successfully received during the slot, and

3) a collision message indicating that at least one packet was detected but could not be successfully received during the slot.

2. An access point for receiving random access communications from a plurality of user elements, the access point comprising:

a) a receiver operable;

to attempt to receive a packet transmitted from at least one of the plurality of user elements during a time slot; and

to determine if a packet was properly received during the time slot;

b) a transmitter operable to transmit a feedback message to the plurality of user elements wherein the feedback message is selected from a group comprising;

1) an idle message indicating that no transmissions were detected during the slot,

2) a successful transmission message indicating that a packet was successfully received during the slot, and

3) a collision message indicating that at least one packet was detected but could not be successfully received during the slot.

3. A method of random access communications from a user element to an access point, the user element being operable to maintain a stack counter, the method comprising:

a) storing at least one packet in a buffer;

b) transmitting the packet for reception by the access point if the stack counter is zero;

c) receiving a feedback message from the access point wherein the feedback message is one of;

1) an idle message indicating that no transmissions were detected during the slot,

2) a successful transmission message indicating that a packet was successfully received during the slot, and

3) a collision message indicating that at least one packet was detected but could not be successfully received during the slot;

d) when the received feedback message is a successful transmission message and the stack counter is zero, removing the transmitted packet from the buffer;

e) when the received feedback message is a collision message, generating a random number and setting the stack counter to an amount determined by the generated random number; and

f) when the received feedback message is an idle message and the stack counter is greater than zero, decrementing the stack counter.

4. A method as defined in claim 3, further comprising repeating steps (b) to (f) as long as there is at least one packet in the buffer.

5. A method as defined in claim 3, wherein the user element is assigned a priority and step (e) comprises, when the received feedback message is a collision message, generating a random number and incrementing the stack counter by an amount determined by the generated random number in combination with the assigned priority.

6. A method as defined in claim 3, further comprising:

receiving a successful transmission message in a time slot in which no packet was transmitted from the user element; and

decrementing the stack counter in response to the received successful transmission message.

7. A user element for random access communications with an access point, the user element comprising:

a) a stack counter;

b) a buffer operable to store at least one packet;

c) a transmitter operable to transmit the packet for reception by the access point if the stack counter is zero;

d) a receiver operable to receive a feedback message from the access point wherein the feedback message is one of;

1) an idle message indicating that no transmissions were detected during the slot,

2) a successful transmission message indicating that a packet was successfully received during the slot, and

3) a collision message indicating that at least one packet was detected but could not be successfully received during the slot;

the buffer being operable, when the received feedback message is a successful transmission message and the stack counter is zero, to remove the transmitted packet from the buffer; and

the stack counter being operable;

(i) when the received feedback message is a collision message, to generate a random number and to set the stack counter to an amount determined by the generated random number; and

(ii) when the received feedback message is an idle message and the stack counter is greater than zero, to decrement the stack counter.

8. A user element as defined in claim 7, wherein the stack counter is operable to repeat steps (i) to (ii) and the transmitter is operable to transmit a packet each time the stack counter is zero as long as there is at least one packet in the buffer.

9. A user element as defined in claim 7, wherein the user element is assigned a priority and the stack counter is operable, when the received feedback message is a collision message, to generate a random number and to increment the stack counter by an amount determined by the generated random number in combination with the assigned priority.

10. A user element as defined in claim 7, wherein the stack counter is further operable to decrement the stack counter in response to receipt of a successful transmission message in a time slot in which no packet was transmitted from the user element.

11. A method of facilitating random access communications at an access point comprising:

a) attempting to receive packets transmitted via a plurality of channels from a plurality of user elements during a time slot;

b) determining a number of successful channels in which packets were properly received during the time slot;

c) determining a number of unsuccessful channels in which packets were not properly received during the time slot; and

d) transmitting a feedback message to the plurality of user elements wherein the feedback message is selected from a group comprising;

1) a merge message when the ratio of successful channels to unsuccessful channels meets a merge message condition;

2) a split message when the ratio of successful channels to unsuccessful channels meets a split message condition, and

3) a stay message when the ratio of successful channels does not meet the merge message condition and does not meet the split message condition.

12. A method as defined in claim 11, wherein the merge message condition comprises the ratio of successful channels to unsuccessful channels exceeding a merge message threshold.

13. A method as defined in claim 11, wherein the split message condition comprises the ratio of successful channels to unsuccessful channels being less than a split channel threshold.

14. A method as defined in claim 11, further comprising transmitting to a user element a successful transmission message indicating that a packet was successfully received from the user element.

15. An access point for receiving random access communications from an plurality of user elements, the access point comprising:

a) a receiver operable;

to attempt to receive packets transmitted via a plurality of channels from the plurality of user elements during a time slot;

to determine a number of successful channels in which packets were properly received during the time slot; and

to determine a number of unsuccessful channels in which packets were not properly received during the time slot; and

b) a transmitter operable to transmit a feedback message to the plurality of user elements wherein the feedback message is selected from a group comprising;

1) a merge message when the ratio of successful channels to unsuccessful channels meets a merge message condition;

2) a split message when the ratio of successful channels to unsuccessful channels meets a split message condition, and

3) a stay message when the ratio of successful channels does not meet the merge message condition and does not meet the split message condition.

16. An access point as defined in claim 15, wherein the merge message condition comprises the ratio of successful channels to unsuccessful channels exceeding a merge message threshold.

17. An access point as defined in claim 15, wherein the split message condition comprises the ratio of successful channels to unsuccessful channels being less than a split channel threshold.

18. An access point as defined in claim 15, wherein the transmitter is further operable to transmit to a user element a successful transmission message indicating that a packet was successfully received from the user element.

19. A method of random access communications from a user element to an access point, the user element being operable to maintain a stack counter, the method comprising:

a) storing at least one packet in a buffer;

b) transmitting the packet for reception by the access point if the stack counter is zero;

c) receiving a feedback message from the access point wherein the feedback message is one of;

1) a merge message when the ratio of successful channels to unsuccessful channels meets a merge message condition;

2) a split message when the ratio of successful channels to unsuccessful channels meets a split message condition, and

3) a stay message when the ratio of successful channels does not meet the merge message condition and does not meet the split message condition.

d) when the received feedback message is a split message, the stack counter is zero and the packet is not successfully transmitted, generating a random number and setting the stack counter to an amount determined by the generated random number;

e) when the received feedback message is one of a merge message and a stay message, the stack counter is zero and the packet is not successfully transmitted, maintaining the stack counter at zero.

20. A method as defined in claim 19, comprising repeating steps (b) to (f) as long as there is at least one packet in the buffer.

21. A method as defined in claim 19, wherein the user element is assigned a priority and step (e) comprises, when the received feedback message is a split message, generating a random number and incrementing the stack counter by an amount determined by the generated random number in combination with the assigned priority.

22. A method as defined in claim 19, further comprising:

receiving a split message when the stack counter is at least one; and

incrementing the stack counter in response to the received split message.

23. A method as defined in claim 19, further comprising:

receiving a stay message when the stack counter is at least one; and

maintaining the value of the stack counter in response to the received stay message.

24. A method as defined in claim 19, further comprising:

receiving a merge message when the stack counter is at least one; and

decrementing the stack counter in response to the received merge message.

25. A method as defined in claim 19, further comprising:

receiving a successful transmission message from the access point; and

removing the transmitted packet from the buffer in response to the successful transmission message.

26. A method as defined in claim 19, further comprising, before transmitting the packet, randomly selecting a channel for transmitting the packet.

27. A method as defined in claim 26, comprising randomly selecting a channel for transmitting a packet at each time slot in which a packet is to be transmitted.

28. A user element for random access communications with an access point, the user element comprising:

a) a stack counter;

b) a buffer operable to store at least one packet;

c) a transmitter operable to transmit the packet for reception by the access point if the stack counter is zero;

d) a receiver operable to receive a feedback message from the access point wherein the feedback message is one of;

1) a merge message when the ratio of successful channels to unsuccessful channels meets a merge message condition;

2) a split message when the ratio of successful channels to unsuccessful channels meets a split message condition, and

3) a stay message when the ratio of successful channels does not meet the merge message condition and does not meet the split message condition.

the stack counter being operable;

(i) when the received feedback message is a split message, the stack counter is zero and the packet is not successfully transmitted, to generate a random number and to set the stack counter to an amount determined by the generated random number; and

(ii) when the received feedback message is one of a merge message and a stay message, the stack counter is zero and the packet is not successfully transmitted, maintaining the stack counter at zero.

29. A user element as defined in claim 28, wherein the stack counter is operable to repeat steps (i) to (ii) and the transmitter is operable to transmit a packet each time the stack counter is zero as long as there is at least one packet in the buffer.

30. A user element as defined in claim 28, wherein the user element is assigned a priority and the stack counter is operable, when the received feedback message is a split message, to generate a random number and to increment the stack counter by an amount determined by the generated random number in combination with the assigned priority.

31. A user element as defined in claim 28, wherein the stack counter is further operable, on receipt of a split message when the stack counter is at least one, to increment the stack counter in response to the received split message.

32. A user element as defined in claim 28, wherein the stack counter is operable, on receipt of a stay message when the stack counter is at least one, to maintain the value of the stack counter in response to the received stay message.

33. A user element as defined in claim 28, wherein the stack counter is operable, on receipt of a merge message when the stack counter is at least one to decrement the stack counter in response to the received merge message.

34. A user element as defined in claim 28, wherein:

the receiver is operable to receive a successful transmission message from the access point; and

the buffer is operable to remove the transmitted packet from the buffer in response to the successful transmission message.

35. A user element as defined in claim 28, wherein the transmitter is operable, before transmitting the packet, to randomly select a channel for transmitting the packet.

36. A user element as defined in claim 35, wherein the transmitter is operable to randomly select a channel for transmitting a packet at each time slot in which a packet is to be transmitted.