WIRELESS COMMUNICATION TERMINAL AND ROAMING METHOD

• US 20090135794A1
• Filed: 09/17/2008
• Published: 05/28/2009
• Est. Priority Date: 11/28/2007
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: CHIANG, MIN-CHIA, SU, CHI-CHUNG
• Granted Patent: US 8,085,732 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 36/26 by agreed or negotiated communication parameters
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A wireless communication terminal roaming from a current access point (AP) to a destination AP within a plurality of APs includes various functional modules. The wireless communication terminal detects a current service quality parameter of each of the plurality of APs, a roaming frequency, and a packet retransmission rate of the wireless communication terminal in a predetermined detection period. Furthermore, the wireless communication terminal calculates a value of an RQI according to the current service quality parameter of each of the plurality of APs, the roaming frequency, and the packet retransmission rate of the wireless communication terminal, and regulates a roaming threshold of the current AP according to the value of the RQI and determines the destination AP that has satisfied a roaming condition corresponding to the value of the RQI.

Claims

1. A wireless communication terminal for roaming from a current access point (AP) to a destination AP within a plurality of APs, comprising:

a detection module configured for detecting a current service quality parameter of each of the plurality of APs, a roaming frequency and a packet retransmission rate of the wireless communication terminal in a predetermined detection period;

a roaming policy regulating module configured for calculating a value of a radio quality index (RQI) according to the current service quality parameter of each of the plurality of APs, the roaming frequency and the packet retransmission rate of the wireless communication terminal, and regulating a roaming threshold of the current AP according to the value of the RQI; and

a roaming determining module configured for determining the destination AP that has satisfied a roaming condition corresponding to the value of the RQI.

2. The wireless communication terminal of claim 1, wherein the current service quality parameter of each of the plurality of APs includes a quality of service basic service set (QBSS) and a receive signal strength indication (RSSI) variance of each of the plurality of APs, wherein the QBSS of each of the plurality of APs represents a current channel utilization rate and a current loading of each of the plurality of APs, and wherein the RSSI variance of each of the plurality of APs is a RSSI variance of each of the plurality of APs in the predetermined detection period, and represents a stability of each of the plurality of APs;

wherein the roaming frequency of the wireless communication terminal is a roaming amount of the wireless communication terminal in a system operation period detected by the detection module in the predetermined detection period, and indicates a communication stability between the wireless communication terminal and each of the plurality of APs, and wherein the communication stability between the wireless communication terminal and each of the plurality of APs decreases when the roaming frequency increases; and

wherein the packet retransmission rate of the wireless communication terminal is a packet retransmission amount in an audio operation period, and wherein the packet retransmission rate of the wireless communication terminal indicates a communication stability between the wireless communication terminal and the current AP, wherein the communication stability between the wireless communication terminal and the current AP decreases when the packet retransmission rate increases.

3. The wireless communication terminal of claim 2, wherein the value of the RQI is equal to a maximum value of the RQI minus iRQI, wherein the maximum value of the RQI is predetermined, and wherein the iRQI is calculated according to following expression:

iRQI=(((an average value of the QBSS/a maximum value of the QBSS)*the maximum value of the RQI)*0.5)+(((current roaming amount/maximum roaming amount)×

the maximum value of the RQI)*0.2)+(((a current packet retransmission rate/a maximum packet retransmission rate)*the maximum value of the RQI)*0.2)+(((an average RSSI variance/a maximum RSSI variance)*the maximum value of the RQI)*0.1).

4. The wireless communication terminal of claim 3, wherein different values of the RQI represent different service qualities of the current AP, and the different service qualities include a normal status, a high traffic status, and an interference status.

5. The wireless communication terminal of claim 4, wherein the roaming threshold comprises differences of the RSSI and the QBSS respectively between the destination AP and the current AP.

6. The wireless communication terminal of claim 5, wherein the roaming condition is that the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold upon the condition that the value of the RQI represents the service quality of the current AP in the normal status.

7. The wireless communication terminal of claim 5, wherein the roaming condition comprises that the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold, the destination AP and the current AP are in different channels, and roaming of the wireless communication terminal to the destination AP should be delayed upon the condition that the value of the RQI represents the service quality of the current AP in the high traffic status.

8. The wireless communication terminal of claim 5, wherein the roaming condition is that the value of the RSSI of the destination AP is greater than that of the current AP while the value of the QBSS of the destination AP is less than those of the current AP and other APs of the plurality of APs upon the condition that the value of the RQI represents the service quality of the current AP in the interference status and the wireless communication terminal in a communication status.

9. The wireless communication terminal of claim 5, wherein the roaming condition comprises that the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold and the value of the QBSS of the destination AP is less than those of the current AP and other APs within the plurality of APs upon the condition that the value of the RQI represents that the service quality of the plurality of APs is in the interference status and the wireless communication terminal is not in a communication status.

10. The wireless communication terminal of claim 1, wherein the roaming determining module is further configured for generating a roaming executing command upon the condition that the destination AP has satisfied the roaming condition corresponding to the value of the RQI.

11. The wireless communication terminal of claim 10, further comprising a roaming executing module configured for ending a communication between the wireless communication terminal and the current AP and establishing a communication between the wireless communication terminal and the destination AP according to the roaming executing command and a value of an RSSI of the destination AP.

12. A roaming method for a wireless communication terminal roaming from a current access point (AP) to a destination AP within a plurality of APs, the method comprising:

detecting a current service quality parameter of each of the plurality of APs, a roaming frequency and a packet retransmission rate of the wireless communication terminal in a predetermined detection period;

calculating a value of a radio quality index (RQI) according to the current service quality parameter of each of the plurality of APs, the roaming frequency and the packet retransmission rate of the wireless communication terminal;

regulating a roaming threshold of the current AP according to the value of the RQI;

determining the destination AP that has satisfied a roaming condition corresponding to the value of the RQI; and

ending a communication between the wireless communication terminal and the current AP and establishing a communication between the wireless communication terminal and the destination AP upon the condition that the destination AP has satisfied the roaming condition corresponding to the value of the RQI.

13. The roaming method of claim 12, further comprising:

generating a roaming executing command upon the condition that the destination AP has satisfied the roaming condition corresponding to the value of the RQI; and

sending the roaming executing command and a value of a receive signal strength indication (RSSI) of the destination AP to a roaming executing module.

14. The roaming method of claim 12, wherein the current service quality parameter of each of the plurality of APs includes a quality of service basic service set (QBSS) and a receive signal strength indication (RSSI) variance of each of the plurality of APs, wherein the QBSS of each of the plurality of APs represents a current channel utilization rate and a current loading of each of the plurality of APs, and wherein the RSSI variance of each of the plurality of APs is a RSSI variance of each of the plurality of APs in the predetermined detection period, and wherein the RSSI variance of each of the plurality of APs represents a stability of each of the plurality of APs;

wherein the roaming frequency of the wireless communication terminal is a roaming amount of the wireless communication terminal in a system operation period in the predetermined detection period, and wherein the roaming frequency of the wireless communication terminal indicates a communication stability between the wireless communication terminal and each of the plurality of APs, and wherein the communication stability between the wireless communication terminal and each of the plurality of APs decreases when the roaming frequency increases; and

wherein the packet retransmission rate of the wireless communication terminal is a packet retransmission amount in an audio operation period, and wherein the packet retransmission rate indicates a communication stability between the wireless communication terminal and the current AP, and wherein the communication stability between the wireless communication terminal and the current AP decreases when the packet retransmission rate increases.

15. The roaming method of claim 14, wherein the value of the RQI is equal to a maximum value of the RQI minus iRQI, the maximum value of the RQI is predetermined, and the iRQI is calculated according to following expression:

iRQI=(((an average value of the QBSS/a maximum value of the QBSS)*the maximum value of the RQI)*0.5)+(((current roaming amount/maximum roaming amount)*the maximum value of the RQI)*0.2)+(((a current packet retransmission rate/a maximum packet retransmission rate)*the maximum value of the RQI)*0.2)+(((an average RSSI variance/a maximum RSSI variance)*the maximum value of the RQI)*0.1).

16. The roaming method of claim 15, wherein different values of the RQI represent different service qualities of the current AP, and the different service qualities of the current AP comprise a normal status, a high traffic status, and an interference status, and wherein the roaming threshold includes differences of the RSSI and the QBSS respectively between the destination AP and the current AP.

17. The roaming method of claim 16, wherein the roaming condition is that the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold upon the condition that the value of the RQI represents that the service quality of the current AP is in the normal status.

18. The roaming method of claim 16, wherein the roaming condition comprises that the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold, the destination AP and the current AP are in different channels, and roaming of the wireless communication terminal to the destination AP should be delayed upon the condition that the value of the RQI represents that the service quality of the current AP is in the high traffic status.

19. The roaming method of claim 16, wherein the roaming condition is that the value of the RSSI of the destination AP is greater than that of the current AP while the value of the QBSS of the destination AP is less than those of the current AP and other APs within the plurality of APs upon the condition that the value of the RQI represents that the service quality of the current AP is in the interference status and the wireless communication terminal is in a communication status.

20. The roaming method of claim 16, wherein the roaming condition comprises the differences of the RSSI and the QBSS respectively between the destination AP and the current AP are greater than those of the roaming threshold and the value of the QBSS of the destination AP is less than those of the current AP and other APs within the plurality of APs upon the condition that the value of the RQI represents that the service quality of the current AP is in the interference status and the wireless communication terminal is not in a communication status.