Method and system for detecting mobility of a wireless-capable modem to minimize data transfer rate renegotiations

• US 6,075,797 A
• Filed: 10/17/1997
• Issued: 06/13/2000
• Est. Priority Date: 10/17/1997
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Thomas, Nicholas A.
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): BOAKYE, ALEXANDER O
• Application Number:
  US08/953,757
• Time in Patent Office: 970 Days
• Field of Search: 370/241, 370/252, 370/310, 370/328, 370/468, 370/465, 375/222, 375/223, 455/557, 455/67.3, 455/226.3
• US Class Current: 370/468
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/22 Negotiating communication rate

Abstract

A method and apparatus for revising and minimizing renegotiations of a data transfer rate for wireless-capable modems transceiving data over a wireless communication channel via a wireless transceiver. When a wireless-capable modem presents a favorable signal-to-noise ratio resulting from a stationary or near stationary position, higher data transfer rates are employed for data exchange. When varying signal-to-noise ratios are detected designating mobility of the wireless-capable modem, then a reduced mobility data transfer rate is employed to provide a sustained data transfer rate for the duration of the mobility without oscillating between differing data transfer rates thereby incurring the significant renegotiation down-time due to fluctuating signal quality. The mobility detection and reduction in the data transfer rate to a more reliable level during mobility is performed automatically without user intervention.

Claims

1. In a data communication system employing a wireless-capable modem transceiving data at a determined data transfer rate via a wireless transceiver, a method for revising and minimizing renegotiations of said data transfer rate when variations to the mobility of said wireless-capable modem are detected, said method comprising the steps of:

a) executing a mobility detection process to determine variations to a signal-to-noise ratio (SNR) of said data received by said wireless-capable modem;

b) when said variations to said SNR exceed a mobility threshold, revising said data transfer rate from a stationary maximum data transfer rate to a mobile default data transfer rate to provide a sustained SNR during mobility of said wireless-capable modem; and

c) when variations to said SNR do not exceed said mobility threshold, revising said data transfer rate to said stationary maximum data transfer rate capable by said wireless-capable modem.

2. The method as recited in claim 1, wherein said executing a mobility detection process step comprises the steps of:

a) statistically selecting an SNR mean and variance for said stationary maximum data transfer rate;

b) calculating said SNR of said data received by said wireless-capable modem; and

c) comparing said SNR against said mean and variance for said stationary maximum data transfer rate to determine said variations to said SNR of said data received by said wireless-capable modem.

3. The method as recited in claim 2, wherein said comparing said SNR against said mean and variance step further comprises the steps of:

a) when said SNR exceeds said mean and variance for said stationary maximum data transfer rate, incrementing an SNR deviation counter to sum successive deviations of said mean and variance for said stationary maximum data transfer rate;

b) when said SNR deviation counter exceeds a count threshold, designating variations to said SNR to exceed said mobility threshold; and

c) when said SNR deviation counter is stable for N seconds, designating said wireless-capable modem as not exceeding said mobility threshold.

4. The method as recited in claim 3, wherein said calculating said SNR of said data received by said wireless-capable modem step comprises the steps of:

a) measuring a plurality of eye scatter samples of said data received by said modem;

b) integrating said plurality of said eye scatter samples to form an integrated value;

c) summing a plurality of said integrated values to form an eye log 2 value; and

d) convert said eye log 2 value to said SNR.

5. The method as recited in claim 1, wherein said executing a mobility detection process step comprises the steps of:

a) calculating a discrete time domain SNR of said data received by said wireless-capable modem;

b) converting said discrete time domain SNR to a frequency domain SNR; and

c) comparing said frequency domain SNR against a high frequency SNR threshold to determine said variations to said SNR of said data received by said wireless-capable modem.

6. The method as recited in claim 5, wherein said comparing said frequency domain SNR against a high frequency SNR threshold step further comprises the steps of:

a) when said SNR exceeds said high frequency threshold, designating variations to said SNR to exceed said mobility threshold; and

b) when said SNR does not exceed said high frequency threshold, designating said wireless-capable modem as not exceeding said mobility threshold.

7. The method as recited in claim 6, wherein said calculating said SNR of said data received by said wireless-capable modem step comprises the steps of:

a) measuring a plurality of eye scatter samples of said data received by said modem;

b) integrating said plurality of said eye scatter samples to form an integrated value;

c) summing a plurality of said integrated values to form an eye log 2 value; and

d) converting said eye log 2 value to said SNR.

8. The method as recited in claim 5, wherein said calculating a time domain SNR of said data received by said wireless-capable modem step further comprises the steps of:

a) detrending said time domain SNR; and

b) smoothing said domain SNR.

9. A wireless-capable modem for transceiving data via a wireless transceiver and capable of revising and minimizing renegotiations of a data transfer rate in response to variations in the mobility of said wireless-capable modem, comprising:

a) a mobility detection process to determine variations to a signal-to-noise ratio (SNR) of said data received by said wireless-capable modem; and

b) a data transfer rate negotiation process for revising said data transfer rate from a stationary maximum data transfer rate to a mobile default data transfer rate to provide a sustained SNR during mobility of said wireless-capable modem when said variations to said SNR exceed a mobility threshold, and when variations to said SNR do not exceed said mobility threshold, said data transfer rate negotiation process for revising said data transfer rate to said stationary maximum data transfer rate capable by said wireless-capable modem.

10. The wireless-capable modem as recited in claim 9, wherein said mobility detection process comprises:

a) means for statistically selecting an SNR mean and variance for said stationary maximum data transfer rate;

b) means for calculating said SNR of said data received by said wireless-capable modem; and

c) means for comparing said SNR against said mean and variance for said stationary maximum data transfer rate to determine said variations to said SNR of said data received by said wireless-capable modem.

11. The wireless-capable modem as recited in claim 10, wherein said means for comparing said SNR against said mean and variance further comprises:

a) means for incrementing an SNR deviation counter to sum successive deviations of said mean and variance for said stationary maximum data transfer rate when said SNR exceeds said mean and variance for said stationary maximum data transfer rate; and

b) means for designating variations to said SNR to exceed said mobility threshold when said SNR deviation counter exceeds a count threshold, and for designating said wireless-capable modem as not exceeding said mobility threshold when said SNR deviation counter is stable for N seconds.

12. The wireless-capable modem as recited in claim 11, wherein said means for calculating said SNR of said data received by said wireless-capable modem comprises:

a) means for measuring a plurality of eye scatter samples of said data received by said modem;

b) means for integrating said plurality of said eye scatter samples to form an integrated value;

c) means for summing a plurality of said integrated values to form an eye log 2 value; and

d) means for converting said eye log 2 value to said SNR.

13. The wireless-capable modem as recited in claim 9, wherein said mobility detection process comprises:

a) means for calculating a discrete time domain SNR of said data received by said wireless-capable modem;

b) means for converting said discrete time domain SNR to a frequency domain SNR; and

c) means for comparing said frequency domain SNR against a high frequency SNR threshold to determine said variations to said SNR of said data received by said wireless-capable modem.

14. The wireless-capable modem as recited in claim 13, wherein said means for comparing said frequency domain SNR against a high frequency SNR threshold further comprises a means for designating variations to said SNR to exceed said mobility threshold when said SNR exceeds said high frequency threshold, and designating said wireless-capable modem as not exceeding said mobility threshold when said SNR does not exceed said high frequency threshold.

15. The wireless-capable modem as recited in claim 13, wherein said means for calculating said SNR of said data received by said wireless-capable modem comprises:

a) means for measuring a plurality of eye scatter samples of said data received by said modem;

b) means for integrating said plurality of said eye scatter samples to form an integrated value;

c) means for summing a plurality of said integrated values to form an eye log 2 value; and

d) means for converting said eye log 2 value to said SNR.

16. The wireless-capable modem as recited in claim 13, wherein said means for calculating a time domain SNR of said data received by said wireless-capable modem further comprises:

a) means for detrending said time domain SNR; and

b) means for smoothing said domain SNR.

17. In a data communication system employing a wireless-capable modem transceiving data at a determined data transfer rate via a wireless transceiver, a method for continuously detecting variations to the mobility of said wireless-capable modem, said method comprising the steps of:

(a) continuously monitoring variations to a signal-to-noise ratio (SNR) value of a data signal being received by the wireless-capable modem;

(b) identifying at least one mobility threshold boundary that indicates that a wireless-capable modem is in a mobile state;

(c) comparing the monitored variations to the SNR value to the mobility threshold boundary; and

(d) if the monitored variations to the SNR value exceeds the SNR threshold, determining that the wireless-capable modem is in a mobile state.