METHOD TO QUITE HIDDEN NODES

• US 20100091717A1
• Filed: 10/14/2008
• Published: 04/15/2010
• Est. Priority Date: 10/14/2008
• Status: Abandoned Application

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Calcev, George, Bonta, Jeffrey D.
• Application Number:
  US12/251,133
• Publication Number:
  US 20100091717A1
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

A method and apparatus for quieting multiple channels on unlicensed spectrum is provided herein. During operation, a cluster head (or centralized controller such as a base station) will listen to determine if channels exist without primary system traffic. A message will then be sent out by the cluster head quieting the channels. All secondary nodes in the cluster will transmit a CTS-to-self if they do not hear any traffic by any primary system node (which may be nodes out of range of the cluster head) on the channels, otherwise they send a NAK on channels not being used by the hidden nodes. If a NAK is received by the cluster head, the process repeats until no NAK has been received. After the primary system is quieted, a poll message is sent by the cluster head to nodes instructing them to send a CTS-to-Self message so that the spectrum is quieted for the period indicated in the message.

Claims

1. A method for a second communication system to quiet channels used by a first communication system, the method comprising the steps of:

monitoring channels used by the first communication system;

determining a group of channels of the first communication system to quiet;

transmitting a first message to nodes in the second communication system over the group of channels;

determining if a negative acknowledgment (NAK) has been received from the nodes in response to the first message, wherein the negative acknowledgment provides an indication that a hidden node exists and is using a channel from the group of channels; and

if no NAK has been received then transmitting a second message to the nodes in the second communication system, instructing the nodes to transmit a message quieting the group of channels.

2. The method of claim 1 wherein the second message comprises a CTS-to-self message containing a Network Allocation Vector (NAV) indicating how long the channel will be occupied.

3. The method of claim 1 wherein any NAK received is received over a channel that is not being used by the first communication system.

4. The method of claim 1 wherein the step of determining the group of channels to quiet comprises determining a group of channels perceived as having no transmissions.

5. The method of claim 1 further comprising the step of:

transmitting information over the group of channels.

6. A method for a node in a secondary communication system to quiet channels used by a primary communication system, the method comprising the steps of:

receiving a first message indicating a group of channels to be quieted;

monitoring the group of channels to determine if any activity is detected on the group of channels by the primary communication system;

If activity is detected then performing the step of transmitting a negative acknowledgment (NAK) indicating that at least one channel from the group of channels are being used by the primary communication system;

if activity is not detected, then performing the steps of;

transmitting a second message quieting the group of channels;

receiving a third message instructing the node to transmit a message quieting the group of channels; and

transmitting a final message quieting the group of channels.

7. The method of claim 6 wherein the first message is received over the group of channels to be quieted.

8. The method of claim 6 wherein the NAK is transmitted over a channel not being used by the first communication system.

9. The method of claim 6 wherein the final message comprises a CTS-to-self message containing a Network Allocation Vector (NAV) indicating how long the channel will be occupied.

16. The node of claim 6 wherein the NAK is transmitted over a channel not being used by the first communication system.

17. The node of claim 6 wherein the final message comprises a CTS-to-self message containing a Network Allocation Vector (NAV) indicating how long the channel will be occupied.

10. An apparatus for a second communication system to quiet channels used by a first communication system, the apparatus comprising:

a receiver monitoring channels used by the first communication system;

logic circuitry determining a group of channels of the first communication system to quiet; and

a transmitter transmitting a first message to nodes in the second communication system over the group of channels, wherein

the logic circuitry additionally determines if a negative acknowledgment (NAK) has been received from the nodes in response to the first message, where the negative acknowledgment provides an indication that a hidden node exists and is using a channel from the group of channels, and if no NAK has been received then the logic circuitry instructs the transmitter to transmit a second message to the nodes in the second communication system instructing the nodes to transmit a message quieting the group of channels.

11. The apparatus of claim 10 wherein the second message comprises a CTS-to-self message containing a Network Allocation Vector (NAV) indicating how long the channel will be occupied.

12. The apparatus of claim 10 wherein any NAK received is received over a channel that is not being used by the first communication system.

13. The apparatus of claim 10 wherein the logic circuitry determines the group of channels to quiet by determining a group of channels perceived as having no transmissions.

14. A node in a secondary communication system that quiets channels used by a primary communication system, the node comprising:

a receiver receiving a first message indicating a group of channels to be quieted and monitoring the group of channels to determine if any activity is detected on the group of channels by the primary communication system;

a transmitter transmitting a negative acknowledgment (NAK) when activity is detected, the NAK indicating that at least one channel from the group of channels are being used by the primary communication system;

the transmitter transmitting a second message quieting the group of channels when activity is not detected and transmitting a final message quieting the group of channels.

15. The node of claim 14 wherein the first message is received over the group of channels to be quieted.