Method for fast link-layer handover in heterogeneous networks

Abstract

When handing off a multi-mode patient monitoring device (PMD) (28) between radio access technology (RAT) networks, a serving access point (AP) (12, 16, 72) with which a communication link is established by the PMD (28) over a first RAT network (RAT-1) to permit the PMD to communicate with a hospital IP network (18) via the serving AP (12, 16, 72). A scanning interface (14, 54, 74, 104) collects information regarding other available RAT networks (e.g., RAT-2 , RAT-3, etc) and candidate APs therein. If the RAT-1 communication quality of service falls below a predetermined threshold level, the serving AP (12, 16, 72) delivers information regarding the candidate APs (22, 24, 26) and their RAT networks to the PMD (28). Delivery of the candidate network / AP information is performed using a beacon signal continuously or periodically emitted from the serving AP (12, 16, 72), or upon request by the PMD (28). The PMD (28) selects a candidate AP (22, 24, 26) as a target AP, and initiates a handover to the target AP. In this manner, the PMD (28) is provided with candidate AP information without having to actively search for the APs, thereby conserving battery power.

Description

technical field [0001] The invention applies to patient monitoring systems, especially to physiological monitoring systems. However, it should be appreciated that the described techniques may also be applied to other monitoring systems, other healthcare information collection schemes, other condition monitoring techniques, and the like. Background technique [0002] A typical wireless patient monitoring system (PMS) includes: 1) one or more patient monitoring devices (PMDs); 2) a patient information server (PIS); and 3) a patient database server (PDS). PMD, PIS and PDS are connected in A network topology. Usually, the hospital's IP network is a wired Ethernet network. PIS and PDS are connected to the wired hospital IP network. The wireless access network connecting the mobile PMDs to the hospital IP network can be based on proprietary or standardized local area network (LAN) technologies, such as IEEE802.11. [0003] The PMD collects the patient's physiological data (ECG...

AI Technical Summary

Problems solved by technology

An arrangement based on the mechanism described by Shin et al. in "Reducing MACLayer Handoff Latency in IEEE 802.11 Wireless LANs" (MobiWac'04, October 2004), although easy to implement, does not prevent time-consuming and consuming access to candidate networks due to stale cache entries. Capable of scanning

Although this mechanism can provide limited information about candidate networks, such as access point channels and MAC addresses, it cannot provide additional information, such as network utilization, which is critical for intelligent access network decisions

[0004] Although IEEE802.21 provides an interesting framework for the distribution of access network information, the disadvantages of its use in PMS include the lack of description of the way the information is collected, and thus the quality of the information is implementation dependent and may not be enough

Another disadvantage is that its signaling overhead may require too much bandwidth for dedicated wireless technologies

In addition, compliance with IEEE802.21 increases power consumption, such as scan requests, etc., which is not conducive to mobile patient monitoring devices

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