KR200427039Y1 - An apparatus for generating a media independent handover - Google Patents

Abstract

An apparatus for generating a medium independent handover (MIH) trigger in a wireless local area network includes a measurement apparatus, a media access control (MAC) apparatus, and a MIH apparatus. The measuring device is configured to make a measurement in the WLAN. The MAC device is configured to communicate with the measurement device and generate a MIH trigger based on the measurement made by the measurement device. The MIH device is configured to communicate with the MAC device and perform handover upon receipt of the MIH trigger from the MAC device.

Medium independent handover (MIH), medium access control (MAC), measurement report request message, measurement entity, handover triggering device

Description

A device for generating a media independent handover trigger {AN APPARATUS FOR GENERATING A MEDIA INDEPENDENT HANDOVER}

1 is a diagram of an existing measurement request frame.

2 is a diagram of a measurement request frame including MIH information.

3 is a diagram of a system configured for synchronized trigger generation and measurement report generation.

4 is a flowchart of a method for synchronized trigger generation and measurement report generation.

5 is a diagram of an apparatus for synchronized trigger generation and measurement report generation.

<Explanation of symbols for the main parts of the drawings>

102, 202: Category field

104, 204: Action field

106,206: Dialog Token Field

108, 208: Repeat count field

210: MIH information field

212: MIH measurement mode field

502: measuring device

504: MAC device

506: MIH device

510 measurement request device

512 measurement evaluation device

514: Handover Triggering Device

The present invention relates generally to wireless local area networks (WLANs) and, more particularly, to a mechanism that provides a trigger for determining if a handover should be performed.

In the study of Media Independent Handover (MIH), whether a new procedure is required to trigger the occurrence of a handover event from a lower layer (ie, MAC and PHY layer) as a means to initiate the handover process. There is a challenge regarding whether it is not required. A trigger is required to determine if handover should be executed. One example of a trigger may be the fact that the signal quality of a particular link layer connection has reached a pre-defined threshold indicating that the client station is approaching the periphery of one cell. There was a resistance to introducing a new trigger procedure. Existing handover processes are proprietary and rely on polling mechanisms to retrieve information from lower layers and make decisions.

There is no procedure or function to generate a trigger for a higher layer based on a state change characterized as a value spanning a threshold set by a higher layer entity. In this case, the higher layer entity is the MIH function. Therefore, what is needed is a way to generate these triggers.

The present invention is a method and system for use in connection with the IEEE 802.21 standard for requesting measurement in the form of an event with respect to existing measurement request and measurement report messages available for 802.11 based and 802.16 based networks. The present invention has the advantages of existing measurement mechanisms, which provide similar information but do not generate triggers.

The present invention provides a method for configuring MIH triggers using existing 802.11k and 802.16 procedures. The trigger is generated towards the upper layer with the occurrence of the measurement report towards the peer. Triggers can also be generated irrespective of peer to peer measurement reporting, but use measurement capabilities from lower layers.

The method of generating a MIH trigger in a WLAN begins by sending a measurement report request message to a measurement entity in the WLAN. The measurement entity makes a measurement and sends a measurement report response message to the MAC function. The MAC function evaluates the measurement and determines whether a handover condition exists based on this measurement. The MAC function generates a MIH trigger if a handover condition exists.

The method of generating a MIH trigger in a WLAN includes determining if a handover condition exists and generating a MIH trigger by the MAC function if the handover condition exists.

Devices for generating MIH triggers in a WLAN include measurement devices, MAC devices and MIH devices. The measuring device is configured to make a measurement in the WLAN. The MAC device is configured to communicate with the measurement device and generate a MIH trigger based on the measurement made by the measurement device. The MIH device is configured to communicate with the MAC device and perform handover upon receipt of the MIH trigger from the MAC device.

The communication frame for providing MIH information in the WLAN includes a MIH information field and a MIH measurement mode field.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The term "station" (STA) hereafter includes a wireless transmit / receive unit (WTRU), a user device, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. This is not limited. As referred to hereinafter, the term "access point" (AP) includes, but is not limited to, a base station, a Node B, a site controller, or any other type of interfacing device in a wireless environment. It doesn't work.

The present invention is based on 802.11 baseline, 802.11a OFDM 5GHz WLAN, 802.11b HR-DSSS 2.4GHz WLAN, 802.11e QoS extension (including WMM and WMM / 2 brands), 802.11g OFDM 2.4GHz WLAN, 802.11j OFDM 10 Applicable to IEEE 802 technologies such as MHz optional WLAN, 802.11k radio resource measurement, 802.11n high-throughput WLAN, 802.11s ESS mesh, 802.11v wireless network management, and 802.21 media independent handover It is not limited. The invention also applies to cellular standards such as 3GPP and 3GPP2, and to standardized or proprietary wireless technologies similar to IEEE 802 WLAN, such as 802.15 Bluetooth, HIPERLAN / 2 and the like.

The present invention provides a method and system for configuring a medium independent handover (MIH) trigger using existing 802.11k and 802.16 procedures. The trigger is generated towards the higher layer in connection with the measurement report generation towards the peer. Triggers can also be generated independent of peer-to-peer measurement reports, but utilize measurement capabilities from lower layers.

The present invention uses triggers as a means for identifying state changes occurring in lower layers. The procedure for changing state is handled at a higher level. As one example, the present invention includes sending a notification, also referred to as a trigger, to a higher layer entity when there is a specific change in the lower layer based on configuration information provided by the higher layer. An example of a change in the lower layer is the ability of the lower layer to provide a predetermined minimum data rate, for example 10 Mbits / sec. This can assume that the upper layer has the means to construct the lower layer to respond to this change. Next, the lower layer will trigger an event notification as soon as the data rate provided by the lower layer falls below 10 Mbits / sec.

Moreover, privateized methods are also available for requesting measurements from lower layer usage polling mechanisms. The polling mechanism is not a desirable solution because there is no real-time component that makes useful measurements, especially when handover is imminent. Using the above example, the upper layer polling mechanism must periodically request data rate information from the lower layer to check whether the data rate requirements have been met. This procedure has two major disadvantages. First, the number of messages required to determine if the state has changed can be quite large. Second, the time required to find out if the state has changed can be longer because polling requires a signal that is at least twice the triggering (one for each poll message and one for each response message).

1 is a diagram of an existing measurement request frame 100. Frame 100 includes a category field 102, an action field 104, a dialog token field 106, a repeat count field 108, and one or more measurement request elements 110. The category field 102 is set to a predetermined value to indicate a radio measurement category. The action field 104 is set to a predetermined value to indicate the measurement request. The dialog token field 106 is set by the STA sending the measurement request frame 100 to identify a particular request. The repeat count field 108 indicates the repeat count to be executed for each of the measurement request elements 110 in the frame 100. Each measurement request element 110 represents a measurement object.

In one embodiment, the present invention uses an automatic configuration of MIH handover parameters. This method is based on the use of existing media access control (MAC) management messages available for both 802.11 and 802.16. In this embodiment, the MIH parameter is added to the measurement request message as shown in FIG.

2 is a diagram of a measurement request frame 200 including MIH information. Frame 200 includes category field 202, action field 204, dialog token field 206, number of iterations field 208, MIH information field 210, MIH measurement mode field 212, and one or more measurements. Request element 214 is included. Fields 202-208 are the same as fields 102-108 described above with respect to FIG. 1. MIH information field 210 indicates that a measurement request message is used for a parameter configured to generate a MIH event. The MIH measurement mode field 212 contains an identifier of the type of measurement to be performed. One example of the contents of the MIH measurement mode field 212 is shown in Table 1; This field can be expanded to include other measurement and reporting options. Each measurement request element 214 represents an object to be measured and reported on.

MIH  Measure mode  field  MIH_B1  MIH_B0  No MIH Support  0  0  MIH configuration is requested, and measurements are aligned with peer measurement reports.  0  One  MIH configuration is requested, and measurements are aligned with peer measurement reports. Measurement request elements apply only to MIH triggers.  One  One

Note that the specific allocation of bits in the message 200 can be changed. The present invention specifically aims at using these measurement messages as alternative MIH configuration delivery means and as a means of accessing measurement capabilities in a lower layer.

3 is a diagram of a system 300 configured for synchronized trigger generation and measurement report generation. System 300 includes a STA 302 and a WLAN node 304. WLAN node 304 may include any type of 802.11 or 802.16 node capable of accommodating MIH functionality. The STA 302 includes a physical layer 310, a MAC layer 312 with a MAC function 314, and an LLC layer 316. The first service access point (SAP) 318 connects the physical layer 310 and the MAC layer 312, and the second SAP 320 connects the MAC layer 312 and the LLC layer 316.

Node 304 includes a physical layer 330, an MCA layer 332 with a MAC function 334, an LLC layer 336, and a MIH layer 338 with a MIH function 340. MIH MAC SAP 342 and SAP 344 connect MAC layer 332 with MIH layer 338.

In the embodiment shown in FIG. 3, node 304 makes a measurement and MAC function 334 generates a measurement report 350 that is sent to STA 302. MAC function 334 also generates an event 352 if the measurement indicates that a handover should occur. Event 352 is sent to MIH MAC SAP 342 and then sent from MIH MAC SAP 342 to SAP 344 where it is processed by MIH function 340.

When the measurement is made in the STA 302, the measurement report 350 is sent from the MAC function 314 in the STA 302 to the MAC function 334 in the node 304 (the measurement report in FIG. 3 ( Arrows can be reversed). MAC function 334 will then evaluate the measurement report to determine whether to trigger event 352.

As shown in FIG. 3, the MIH trigger occurrence (event 352) is synchronized with the measurement report 350. This addresses the specific case where an event is triggered towards the higher layer, in which case it is triggered towards the MIH layer 338 with the measurement report message 350 generated towards the MAC peer entity 314 in particular. Event 352 is triggered from a higher layer, and measurement report 350 may occur at the same time.

Note that handover trigger event 352 can be generated by MAC function 334 without the presence of measurement report 350. Event 352 may be triggered periodically or based on internal monitoring by node 304. In addition, those skilled in the art will appreciate that various other ways to generate the handover trigger event 352 can be contemplated. There are typically three modes of operation when reporting a measurement; The STA is configured for one particular mode of operation. One mode is to send measurements towards peer entities (eg, other STAs and one AP) and at the same time send a trigger towards the MIH function. The second mode is to trigger the MIH function when the measurement is available. The third mode is to report the measurement towards the peer entity (ie when the MIH bit is turned off).

4 is a flowchart of a method 400 for synchronized trigger generation and measurement report generation. The method begins by sending a measurement report request message to a measurement entity in the WLAN (step 402). The measurement is made by the measurement entity and the measurement report response message is sent by the measurement entity and received by the MAC function in the WLAN node including the MIH function (step 404). The MAC function evaluates the measurement (step 406) and determines if the handover trigger condition is met (step 408). If the handover trigger condition is not met, the method ends (step 410).

If the handover trigger condition is met (step 408), the MAC function generates a handover trigger message (step 412). The MAC function sends a handover trigger message to the MIH function (step 414) and the method ends (step 410).

In an alternative embodiment of the method 400, the measurement report message is not sent and the method begins at step 408 where the MAC function determines if a handover trigger condition is met.

5 is a diagram of an apparatus 500 for synchronized trigger generation and measurement report generation. Device 500 includes a measurement device 502, a MAC device 504 in communication with the measurement device 502, and a MIH device 506 in communication with the MAC device 504. The MAC device includes a measurement request device 510, a measurement evaluation device 512, and a handover triggering device 514.

In operation, the measurement request device 510 sends a measurement report request message 520 to the measurement device 502. The measurement device 502 makes the requested measurement and sends a measurement report response message 522 to the measurement evaluation device 512. The measurement evaluation device 512 evaluates the measurement and determines whether a handover is required. If a handover is required, the measurement evaluation device generates an event 524 that is sent to the handover triggering device 514. The handover triggering device 514 sends a handover triggering message 526 to the MIH device 506, and the MIH device 506 begins to execute the handover.

Although the features and elements of the present invention have been described in the preferred embodiments in particular combinations, each feature or element may be used alone or in combination with or other features and elements of the present invention. Can be used in various combinations without elements.

According to the present invention, MIH triggers can be generated using existing 802.11k and 802.16 procedures.

Claims (10)

An apparatus for generating a medium independent handover (MIH) trigger in a wireless local area network (WLAN), A measuring device configured to make a measurement related to items for evaluating handover in a WLAN; A media access control (MAC) device in communication with the measurement device and configured to generate a MIH trigger based on the measurement made by the measurement device; And A MIH device in communication with the MAC device, the MIH device configured to execute a handover upon receipt of the MIH trigger from the MAC device Medium independent handover trigger generating device comprising a. The apparatus of claim 1, wherein the measurement device is configured to send a measurement report message that includes the measurement made. 3. The apparatus of claim 2, wherein the MAC device is configured to send a measurement report request message to the measurement device to request the measurement device to make the measurement. 4. The apparatus of claim 3, wherein the measurement report request message includes a list of elements for measurement by the measurement device. The method of claim 1, wherein the MAC device, A measurement request device in communication with the measurement device; A measurement evaluation device in communication with the measurement device; And Handover triggering device in communication with the measurement evaluation device and the MIH device Media independent handover trigger generating device comprising a. 6. The apparatus of claim 5, wherein the measurement request device is configured to send a measurement report request message to the measurement device to request the measurement device to perform the measurement. 7. The apparatus of claim 6, wherein the measurement report request message includes a list of elements for measurement by the measurement device. 7. The apparatus of claim 6, wherein the measurement device is configured to send a measurement report message including the measurement made to the measurement evaluation device. 6. The apparatus of claim 5, wherein the measurement evaluation device is configured to evaluate the measurement and is configured to generate an event if the measurement indicates that a handover condition exists and the event is sent to the handover triggering device. Media independent handover trigger generator. 10. The apparatus of claim 9, wherein the handover triggering device is configured to send a handover trigger message to the MIH device upon receipt of the event.

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