Multi-access system and method using multi-sectored antenna

• US 7,359,679 B2
• Filed: 01/28/2005
• Issued: 04/15/2008
• Est. Priority Date: 01/28/2005
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: King, Wayne G., Giaimo, Edward C. III, Brennan, James, Ranta, Craig Steven
• Primary Examiner(s): LE, THANH C
• Application Number:
  US11/045,687
• Publication Number:
  US 20060172711A1
• Time in Patent Office: 1,173 Days
• Field of Search: None
• US Class Current: 455/101
• CPC Class Codes: H04B 7/061 using feedback from receiving side

Abstract

A wireless access point is equipped with both an omnidirectional antenna and a directable antenna that can be selectively directed to any of a plurality of directional spaces overlapping the network space served by the omnidirectional antenna. The directable antenna is directed to an optimal directional space for a client when the access point is communicating with the client at a high data rate. The access point can intermittently exchange information with other clients using the omnidirectional antenna. The omnidirectional antenna enables broadcast signals to be transmitted to any client in the entire network space, but at a lower data rate. A preferred data rate and an optimal client directional space are re-determined periodically or as necessary based on parameters such as the data rate, signal strength, and rate of success in communicating data.

Claims

1. A method for controlling communication between an access point and a client in a wireless network, comprising the steps of:

(a) providing an omnidirectional antenna that is used for wireless communications with clients disposed around the omnidirectional antenna, in a network space;

(b) providing a directable antenna that is selectively controlled to provide coverage of any of a plurality of different directional spaces, each of the directional spaces overlapping a portion of the network space;

(c) identifying a client directional space from among the plurality of different directional spaces, the client directional space facilitating a higher communication rate between the access point and the client than a basic communication rate available between the access point and the client using the omnidirectional antenna;

(d) selecting one of the omnidirectional antenna and the directable antenna for communicating with the client based on at least one of;

(i) a characteristic of a transmission communicated between the access point and client; and

(ii) a characteristic of the wireless network; and

(e) when the directable antenna is selected, selectively directing the directable antenna to the client directional space.

2. The method of claim 1, further comprising the step of identifying an optimal directional space from among the plurality of directional spaces, the optimal directional space facilitating a highest communication rate between the access point and the client among the plurality of directional spaces.

3. The method of claim 2, wherein the step of identifying the optimal client directional space comprises the step of directing the directable antenna to at least a subset of the plurality of directions;

and at least one of the steps of;

(a) comparing one of a signal strength and a signal to noise ratio of a plurality of communications received from the client and selecting as the client directional space a directional space for which one of the signal strength and the signal to noise ratio is the greatest;

(b) comparing one of a client signal strength and a client signal to noise ratio measured by the client for at least one polling communication received from the access point while the directable antenna was directed to an identifiable directional space determinable from a label appended to the polling communication; and

(c) comparing a communication success rate for a plurality of communications exchanged with the client and selecting as the client directional space a direction space for which the communication success is highest.

4. The method of claim 3, wherein the communication success rate is determinable from at least one of:

(a) a packet error rate;

(b) a number of acknowledgement failures; and

(c) a number of transmissions that are resent before a transmission is successfully received.

5. The method of claim 3, further comprising the step of transmitting a plurality of polling signals from the access point to the client, receipt of each of the polling signals causing the client to transmit a responsive communication for the access point to evaluate.

6. The method of claim 1, wherein upon directing the directable antenna to the client directional space, further comprising the step of causing the communication rate to be increased between the client and the access point, by at least one of:

(a) increasing a data downlink transmission rate when transmitting data from the access point to the client; and

(b) sending an increase transmission rate message from the access point to the client commanding the client to increase an uplink transmission rate when the client is transmitting data to the access point.

7. The method of claim 1, further comprising maintaining an association table at the access point, the association table including an entry for the client indicating at least one of:

(a) a preferred omnidirectional communication rate to be used when the omnidirectional antenna is selected for communicating with the client; and

(b) a preferred directional communication rate to be used when the directable antenna is selected and directed to the client directional space designated for the client.

8. The method of claim 1, wherein a characteristic of a transmission communicated between the access point and the client includes at least one of:

(a) a volume of data in the transmission; and

(b) a priority associated with the transmission.

9. The method of claim 1, wherein the characteristic of the wireless network includes at least one of:

(a) a rate at which data communications are exchanged between the access point and the client;

(b) a likelihood of a large volume of data being exchanged with the client based on a record of past communications with the client;

(c) a reduced demand among other clients to communicate with the access point;

(d) a reduced demand among other clients to exchange large volumes of data with the access point; and

(e) a client priority assigned to the client.

10. The method of claim 1, wherein transmissions intended for all clients within the communication area are broadcast using the omnidirectional antenna.

11. The method of claim 1, further comprising the step of preventing a first client not in direct communication range with a second client from transmitting while the access point is communicating with the second client including one of:

(a) before transmitting to the second client, transmitting on the omnidirectional antenna at least one protection mechanism frame adapted to prevent the first client from transmitting while communicating with the second client; and

(b) upon receiving a request to send (RTS) frame from the second client, transmitting on the omnidirectional antenna a clear to send (CTS) frame to the second client.

12. A method for controlling communication between an access point and a client in a wireless network, comprising the steps of:

(a) providing an omnidirectional antenna that is used for wireless communications with clients disposed around the omnidirectional antenna, in a network space;

(b) providing a directable antenna that is selectively controlled to provide coverage of any of a plurality of different directional spaces, each of the directional spaces overlapping a portion of the network space;

(c) identifying an optimal client directional space from among the plurality of different directional spaces, the optimal directional space facilitating a highest communication rate between the access point and the client among the plurality of directional spaces;

(d) identifying a preferred directional communication rate for use when the directable antenna is directed to the optimal directional client space;

(e) selecting one of the omnidirectional antenna and the directable antenna for communicating with the client; and

(f) when the directable antenna is selected;

(i) directing the directable antenna to the optimal client directional space; and

(ii) communicating with the client using the preferred directional communication rate.

13. The method of claim 12, wherein the step of identifying the optimal client directional space includes the steps of directing the directable antenna to at least a subset of the plurality of different directional spaces;

and at least one of the steps of;

(a) comparing one of a signal strength and a signal to noise ratio of a plurality of communications received from the client and selecting as the optimal client directional space a directional space for which one of the signal strength and the signal to noise ratio is the greatest;

(b) comparing one of a client signal strength and a client signal to noise ratio measured by the client for at least one polling communication received from the access point while the directable antenna was directed to an identifiable directional space determinable from a label appended to the polling communication; and

(c) comparing a communication success rate for a plurality of communications exchanged with the client and selecting as the optimal client directional space a direction for which the communication success rate is highest.

14. The method of claim 13, further comprising the step of transmitting a plurality of polling signals from the access point to the client, receipt of each of the polling signals causing the client to transmit a responsive communication for the access point to evaluate.

15. The method of claim 12, further comprising the step, upon directing the directable antenna to the optimal client directional space, causing the communication rate to be increased between the client and the access point, by at least one of:

(a) increasing a data downlink transmission rate when transmitting data from the access point to the client; and

(b) sending an increase transmission rate message signaling the client to increase an uplink transmission rate, when the client is transmitting data to the access point.

16. The method of claim 12, further comprising the step of maintaining an association table in the access point, the association table including an entry for the client including at least one of:

(a) a preferred omnidirectional communication rate to be used when the omnidirectional antenna is selected for communicating with the client; and

(b) the preferred directional communication rate to be used when the directable antenna is selected and directed to the optimal client directional space.

17. The method of claim 12, wherein the step of selecting one of the omnidirectional antenna and the directable antenna for communicating with the client includes the step of evaluating at least one of:

(a) a volume of data for the transmission;

(b) a priority associated with the transmission;

(c) a rate with which data communications are exchanged between the access point and the client;

(d) a likelihood of a large volume of data being exchanged with the client based on a record of past communications exchanged with the client;

(e) a reduced demand among other clients to communicate with the access point;

(f) a reduced demand among other clients to exchange large volumes of data with the access point;

(g) a client priority assigned to the client; and

(h) whether a transmission is intended for at least one other client at least potentially within the network space, in addition to the client.

18. The method of claim 12, further comprising the step of preventing a first client not in direct communication range with a second client from transmitting while the access point is communicating with the second client including one of:

(a) before transmitting to the second client, transmitting on the omnidirectional antenna at least one protection mechanism frame adapted to prevent the first client from transmitting while communicating with the second client; and

(b) upon receiving a request to send (RTS) frame from the second client, transmitting on the omnidirectional antenna a clear to send (CTS) frame to the second client.

19. A networking system for communicating with at least one client in a wireless network, comprising:

(a) an antenna subsystem, including;

(i) an omnidirectional antenna configured to provide coverage of a network space around the omnidirectional antenna;

(ii) a directable antenna that is controllable to provide coverage of any of a plurality of different directional spaces, each of the directional spaces overlapping a portion of the network space; and

(iii) an antenna switch coupled to both the omnidirectional antenna and the directable antenna, the antenna switch being configured to select one of the omnidirectional antenna and the directable antenna for at least one of a downlink and an uplink communication;

(d) a processor;

(e) a communication interface in communication with a network, the antenna subsystem, and the processor; and

(c) a memory in communication with the processor, the memory storing data and machine instructions that cause the processor to carry out a plurality of functions, including;

(i) identifying a client directional space from among the plurality of directional spaces, the client directional space facilitating a higher communication rate between the access point and the client than a basic communication rate that is available between the access point and the client using the omnidirectional antenna;

(ii) selecting one of the omnidirectional antenna and the directable antenna for communicating with the client based on at least one of;

(A) a characteristic of a transmission communicated between the access point and client; and

(B) a characteristic of the wireless network; and

(iii) when the directable antenna is selected, directing the directable antenna to the client directional space.

20. The networking system of claim 19, wherein the machine instructions further cause the processor to identifying an optimal directional space as the client directional space, from among the plurality of different directional spaces, the optimal directional space facilitating a highest communication rate between the access point and the client among the plurality of directional spaces.