Adaptive handover apparatus and method in a heterogeneous network environment

• US 8,126,465 B2
• Filed: 02/14/2009
• Issued: 02/28/2012
• Est. Priority Date: 10/03/2008
• Status: Expired due to Fees

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Lu, Yi-Hung, Cheng, Yong-Hua
• Primary Examiner(s): Edouard, Patrick
• Assistant Examiner(s): PEREZ, JULIO R
• Application Number:
  US12/371,589
• Publication Number:
  US 20100087195A1
• Time in Patent Office: 1,109 Days
• Field of Search: 455/436, 455/437, 455/438, 455/440, 455/443
• US Class Current: 455/436
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 36/144 over a different radio air interface technology
• CPC Class Codes: H04W 36/302 due to low signal strength

Abstract

An adaptive handover method in a heterogeneous network environment collects estimation information for a channel environment and integrates with a wireless device'"'"'s geographic information to decide two groups of recursive parameters and a channel theoretical signal model. The model and the first group of recursive parameters are used to execute recursive iteration for a signal strength decay theoretical value. The obtained actual signal strength decay value from channel estimation, the second group of recursive parameters and the signal strength decay estimation value at previous iteration are used to execute channel-tracking recursive iteration for obtaining a signal strength decay tracking value. The current network status and the signal strength decay tracking value are used to predict and analyze system performance of heterogeneous networks. A decision is made based on each heterogeneous network'"'"'s analyzed result, and an adaptive handover procedure is prepared by following the decision.

Claims

1. An adaptive handover apparatus for a heterogeneous network environment, comprising:

an adaptive model control unit, collecting estimation information of a channel environment when a wireless device starting up, and integrating geographical information of said wireless device to determine a first group and a second group of recursive parameters and a channel theoretic model;

a power gain prediction unit, based on said channel theoretic model and said first group of recursive parameters, performing recursive computation on signal strength decay theoretic value, and based on actual signal strength decay value predicted by said channel estimation, said second group of recursive parameters and said recursive computation of signal strength decay estimated value of previous iteration, performing recursive computation on channel tracking to obtain signal strength decay tracking value;

a heterogeneous networks analysis unit, based on said signal strength decay tracking value and current wireless network state information, performing prediction and analysis on heterogeneous network performance and adjusting prediction time of the change on signal strength decay of heterogeneous networks; and

a handover decision unit, based on said heterogeneous performance analysis to reach a decision and based on said decision to prepare adaptive switching of heterogeneous networks;

wherein said power gain prediction unit uses said actual signal strength decay value predicted by said channel, said second group of recursive parameters and said recursive computation of signal strength decay estimated value at previous iteration as input to an algorithm to establish a second mathematic recursive model for performing said recursive computation on channel tracking.

2. The adaptive handover apparatus as claimed in claim 1, wherein said heterogeneous network environment is a diverse heterogeneous network environment.

3. The adaptive handover apparatus as claimed in claim 1, said apparatus realize handover in heterogeneous network through a plurality of system signals.

4. The adaptive handover apparatus as claimed in claim 1, wherein said power gain prediction unit uses said channel theoretic model and said first group of recursive parameters as input to an algorithm to establish a first mathematic recursive model for performing said recursive computation on signal strength decay theoretic value.

5. The adaptive handover apparatus as claimed in claim 1, wherein said geographical information of said wireless device further includes information on moving speed and relative location of said wireless device.

6. The adaptive handover apparatus as claimed in claim 1, wherein said geographical information of said wireless device is information obtained through a global positioning system.

7. The adaptive handover apparatus as claimed in claim 1, wherein information of said first group of recursive parameters, said second group of recursive parameters and said channel theoretic model is recorded in an environment information table.

8. An adaptive handover apparatus for a heterogeneous network environment, comprising:

an adaptive model control unit, collecting estimation information of a channel environment when a wireless device starting up, and integrating geographical information of said wireless device to determine a first group and a second group of recursive parameters and a channel theoretic model;

a power gain prediction unit, based on said channel theoretic model and said first group of recursive parameters, performing recursive computation on signal strength decay theoretic value, and based on actual signal strength decay value predicted by said channel estimation, said second group of recursive parameters and said recursive computation of signal strength decay estimated value of previous iteration, performing recursive computation on channel tracking to obtain signal strength decay tracking value;

a heterogeneous networks analysis unit, based on said signal strength decay tracking value and current wireless network state information, performing prediction and analysis on heterogeneous network performance and adjusting prediction time of the change on signal strength decay of heterogeneous networks; and

a handover decision unit, based on said heterogeneous performance analysis to reach a decision and based on said decision to prepare adaptive switching of heterogeneous networks;

wherein said power gain prediction unit further includes;

a theoretic value recursive computation module, according to said channel theoretic model and said first group of recursive parameters and taking them as input to a mathematic recursive model for performing prediction update of signal strength decay value; and

a channel tracking recursive computation module, according to said actual signal strength decay value predicted by said channel, said second group of recursive parameters and said recursive computation of signal strength decay estimated value at previous iteration and taking them as input to another mathematic recursive model for performing said recursive computation on channel tracking to obtain signal strength decay tracking value.

9. A handover method for a heterogeneous network environment, comprising:

when a wireless device starting up, collecting channel environment estimation information and integrating with said wireless device'"'"'s geographic information to decide a first and a second groups of recursive parameters and a channel theoretical model;

based on said channel theoretic model and said first group of recursive parameters, executing recursive iteration for a signal strength decay theoretical value, and based on actual signal strength decay value from channel estimation, said second group of recursive parameters and said signal strength decay estimation value at previous iteration, executing recursive iteration on channel tracking for obtaining a signal strength decay tracking value;

based on current network status and said signal strength decay tracking value, predicting and analyzing system performance of heterogeneous networks, and adjusting prediction time of estimating the change on signal strength decay of heterogeneous networks; and

based on each heterogeneous network'"'"'s analyzed result, making a decision and based on said decision, preparing for an adaptive switching in heterogeneous networks;

wherein said method uses said channel theoretic model and said first group of recursive parameters as input to an algorithm to establish a first mathematic recursive model for performing said recursive computation on signal strength decay theoretic value, and uses said actual signal strength decay value predicted by said channel, said second group of recursive parameters and said recursive computation of signal strength decay estimated value of previous iteration as input to another algorithm to establish another mathematic recursive model for performing recursive computation on channel tracking to obtain a signal strength decay tracking value.

10. The adaptive handover method as claimed in claim 9, wherein said algorithm is least mean square algorithm.

11. The adaptive handover method as claimed in claim 9, wherein said another algorithm is least mean square algorithm.

12. The adaptive handover method as claimed in claim 9, wherein said preparation of adaptive switching in heterogeneous networks is preparation adaptive switching in heterogeneous networks between communication physical layer and network layer.

13. The adaptive handover method as claimed in claim 9, said method adjusts, based on said analysis result, prediction time for estimating the change on signal strength decay of heterogeneous networks.

14. The adaptive handover method as claimed in claim 9, said method targets different heterogeneous network environments and performs recursive computation on said signal strength decay theoretic value and said recursive computation on channel tracking through least mean square algorithms.

15. The adaptive handover method as claimed in claim 9, wherein after handover is completed, said method returns to said step of:

when a wireless device starting up, collecting channel environment estimation information and integrating with said wireless device'"'"'s geographic information to decide a first and a second groups of recursive parameters and a channel theoretical model.