METHOD FOR OPTIMIZING NEAR FIELD LINKS

• US 20080291852A1
• Filed: 09/14/2007
• Published: 11/27/2008
• Est. Priority Date: 05/23/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Abel, Miller T.
• Granted Patent: US 8,400,913 B2
• Time in Patent Office: Days
• US Class Current: 370/296
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04L 2007/045 Fill bit or bits, idle words
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04W 72/569 of the traffic information
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In a Near Field Communications (NFC) link, the data link turn-around time is adjusted to optimize battery use while maximizing the data throughput. A receiving device immediately transmits any pending high priority control or data messages in its own queue in response to a message from the sending device, subject to the flow control status of the sending device. The value of the delay time before sending a SYMM primitive is selected in accordance with the types of link frames recently received.

Claims

1. A method for coordinating data communication in a half duplex link, the method comprising:

receiving a data packet;

determining a type of information included in said data packet;

setting a transmission delay, wherein said transmission delay accounts for said type, said transmission delay being decreased when said type indicates that data transmission on said link is active, and said transmission delay being increased when said type indicates that data transmission on the link is idle;

transmitting a data packet when a data packet is pending;

when no data packet is pending, transmitting a synchronization packet after lapse of said transmission delay.

2. The method of claim 1, further comprising determining said transmission delay using a timer, said timer further comprising the product of an idle factor and an idle delay.

3. The method of claim 2, wherein said idle factor is computed as follows:

when the link is first established the idle factor is set to zero;

incrementing said idle factor when said type indicates that data transmission on said link is idle; and

reducing said idle factor when said type indicates that data transmission on said link is active.

4. The method of claim 3, wherein said idle factor is set to a predetermined value when said type indicates that data transmission on said link is active and said type comprises a control data packet.

5. The method of claim 4, wherein said transmitting further comprises:

starting said timer when the idle factor is greater than zero, and

transmitting a synchronization packet when said timer expires.

6. The method of claim 4, wherein said predetermined value is at least one of:

based upon a priority of said data packet, a random time period, negotiated with a second device, a sliding scale, or mathematical relationship.

7. A method for coordinating data communication in a Near Field Communication link, the method comprising:

receiving a data frame;

determining a type of information included in said data frame;

setting a transmission delay to zero when said type is an information frame, increasing said transmission delay when said type is a synchronization frame, otherwise setting said transmission delay to a predetermined level;

transmitting a data frame when at least one data frame is pending; and

when no data frame is pending, transmitting a synchronization message after lapse of said transmission delay.

8. The method of claim 7, further comprising determining said transmission delay using a timer, said timer further comprising the product of an idle factor and an idle delay.

9. The method of claim 8, wherein said idle factor is computed as follows:

when the link is first established the idle factor is set to zero;

when said type is a synchronization frame said idle factor is incremented; and

otherwise said idle factor is reduced or set to zero.

10. The method of claim 9 wherein said idle factor is set to a predetermined value when said type is a control frame.

11. The method of claim 10, wherein said transmitting further comprises:

starting said timer when the idle factor is greater than zero, and

transmitting a synchronization frame when said timer expires.

12. The method of claim 10, wherein said idle factor is determined according to at least one of:

a mathematical relationship, a priority of said data packet, or a random time period.

13. The method of claim 7, wherein said transmission delay is negotiated with a second device.

14. A Near Field Communication device, said device comprising:

a receiver for receiving a data frame;

a transmitter for transmitting a data frame; and

a transmission control component that;

determines a type of information included in said data frame, sets a transmission delay to zero when said type is an information frame, increases said delay when said type is a synchronization frame, and otherwise sets said delay to a predetermined level;

commands said transmitter to transmit a data frame after lapse of said delay when at least one data frame is pending;

and commanding said transmitter to transmit a synchronization message after lapse of said delay when no data frame is pending.

15. The device of claim 14, wherein said transmission delay further comprises a timer, said timer comprised of a product of an idle factor and an idle delay.

16. The device of claim 15, wherein said idle factor is computed as follows:

when the link is first established the idle factor is set to zero;

when said type is a synchronization frame said idle factor is incremented; and

otherwise said idle factor is reduced or set to zero.

17. The device of claim 16 wherein said idle factor is set to a predetermined value when said type is a control frame.

18. The device of claim 17, wherein said transmission control component also starts said timer when the idle factor is greater than zero, and transmits a synchronization frame when said timer expires.

19. The device of claim 17, wherein said idle factor is determined according to at least one of:

a mathematical relationship, a priority of said data packet, or a random time period.

20. The device of claim 14, wherein said transmission delay is negotiated with a second device.