Method for optimizing near field links

• US 8,400,913 B2
• Filed: 09/14/2007
• Issued: 03/19/2013
• 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.
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): KHIRODHAR, MAHARISHI V
• Application Number:
  US11/855,913
• Publication Number:
  US 20080291852A1
• Time in Patent Office: 2,013 Days
• Field of Search: 370/230, 370/231, 370/232, 370/235, 455/67.11, 4551151-1154
• US Class Current: 370/230
• 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. In a device configured to communicate with at least one other device in a half duplex link, a method for coordinating data communication in the half duplex link, the method comprising:

receiving, by the device, a data packet;

determining, by the device, a type of information included in said data packet;

initializing, by the device, a data transmission delay and storing the data transmission delay in the device;

decreasing said data transmission delay when said type indicates that data transmission on said link is active, and increasing said data transmission delay when said type indicates that data transmission on the link is idle;

transmitting, by the device, a data packet to the at least one other device when a data packet is pending; and

when no data packet is pending, transmitting, by the device, a synchronization packet to the at least one other device after lapse of said data transmission delay.

2. The method of claim 1, further comprising determining said data 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. In a device configured to communicate with at least one other device in a Near Field Communication (NFC) link, a method for coordinating data communication in the NFC link, the method comprising:

receiving, by the device, a data frame;

determining, by the device, a type of information included in said data frame;

setting, by the device, a data transmission delay to zero when said type is an information frame, increasing said data transmission delay when said type is a synchronization frame, and otherwise setting said data transmission delay to a predetermined level, the data transmission delay comprising a product of an idle factor and an idle delay;

transmitting, by the device, a pending data frame to the at least one other device when at least one data frame is pending; and

when no data frame is pending, transmitting, by the device, a synchronization message to the at least one other device after lapse of said data transmission delay.

8. The method of claim 7, 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.

9. The method of claim 8 wherein said idle factor is set to a predetermined value when said type is a control frame.

10. The method of claim 9, 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.

11. The method of claim 9, 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.

12. The method of claim 9, wherein said data transmission delay is negotiated with a second device.

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

a receiver configured to receive a data frame;

a transmitter configured to transmit a pending data frame; and

a transmission control component configured to;

determine a type of information included in said data frame, set a data transmission delay to zero when said type is an information frame, increase said data transmission delay when said type is a synchronization frame, and otherwise set said data transmission delay to a predetermined level, the data transmission delay determined as a product of an idle factor and an idle delay;

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

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

14. The device of claim 13, 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.

15. The device of claim 14 wherein said idle factor is set to a predetermined value when said type is a control frame.

16. The device of claim 15, 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.

17. The device of claim 15, 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.

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