Vertical roaming in wireless networks through improved quality of service measures

• US 7,154,869 B2
• Filed: 06/27/2005
• Issued: 12/26/2006
• Est. Priority Date: 02/28/2003
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Guo, Zihua, Zhang, Qian, Zhu, Wenwu, Yao, Richard
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): ABELSON, RONALD B
• Application Number:
  US11/168,254
• Publication Number:
  US 20050250508A1
• Time in Patent Office: 547 Days
• Field of Search: 370331-333, 455436-442
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/22 for handling the traffic

Abstract

A system and method for improved vertical handoff between different types of wireless network. Network allocation vector occupation and packet collision probability are used as quality of service measures, enabling vertical handoffs to be delayed until actually beneficial to quality of service. Improved wireless network cell boundary detection in vertical handoff scenarios is achieved with a Fourier-based technique in conjunction with an adaptively determined minimum operating signal strength threshold. Improved wireless network cell boundary detection enables vertical handoffs from high quality of service networks to be delayed as long as possible. Together, practical wireless network quality of service measures and improved detection of wireless network cell boundaries in vertical handoff scenarios reduce the rate of unnecessary vertical handoff resulting in higher overall quality of service experienced by a mobile computing device roaming between wireless network types.

Claims

1. A computing device comprising:

at least one wireless network interface;

a network device interface operatively connected to the at least one wireless network interface; and

a vertical roaming manager comprising;

a multi-network manager configured to, at least;

monitor the at least one wireless network interface with the network device interface, the monitoring comprising sampling a network allocation vector for a period of time; and

generate at least one quality of service measure; and

a policy manager configured to, at least, receive the at least one quality of service measure from the multi-network manager.

2. The computing device of claim 1, wherein the multi-network manager is further configured to generate network status notifications and the policy manager is further configured to receive the network status notifications from the multi-network manager.

3. The computing device of claim 1, wherein the multi-network manager is further configured to calculate a network allocation vector occupation comprising calculating a ratio of an amount of time that the network allocation vector is busy during the time period to a total amount of time during that time period.

4. The computing device of claim 3, wherein the at least one quality of service measure comprises a linear function of the network allocation vector occupation.

5. The computing device of claim 4, wherein a low network allocation vector occupation corresponds to a high quality of service measure and a high network allocation vector occupation corresponds to a low quality of service measure.

6. The computing device of claim 5, wherein the at least one quality of service measure comprises an estimated residual bandwidth.