HK1134175B - Methods and apparatus for providing a handover control system associated with a wireless communication network - Google Patents

Description

Method and apparatus for providing a handover control system associated with a wireless communication network

Technical Field

The present disclosure relates generally to wireless communication systems, and more particularly, to methods and apparatus for providing a handover control system associated with a wireless communication network.

Background

As wireless communication becomes more and more popular in offices, homes, schools, etc., various wireless technologies and applications need to cooperate in tandem to meet the demand for computing and communication at any time and/or anywhere. For example, multiple and/or multiple wireless communication networks may coexist to provide a wireless communication environment with greater computing and/or communication capabilities, greater mobility, and/or ultimately seamless roaming.

In particular, a Wireless Personal Area Network (WPAN) may provide fast, short-range connectivity within a relatively small space, such as an office workspace or a room in a home. In office buildings, homes, schools, etc., Wireless Local Area Networks (WLANs) may provide a wider range than WPANs. For example, Wireless Metropolitan Area Networks (WMANs) connect buildings to each other over a wider geographical range and are therefore able to cover greater distances than WLANs. As these networks find widespread use in the cellular infrastructure, Wireless Wide Area Networks (WWANs) may provide the widest range. Although each of the above wireless communication networks support different uses, the coexistence between these networks provides a more robust environment with anytime and anywhere connectivity.

Drawings

Fig. 1 is a diagram illustrating an exemplary wireless communication system in accordance with embodiments of the method and apparatus of the present invention.

Fig. 2 is a block diagram illustrating an exemplary Wireless Local Area Network (WLAN).

Fig. 3 depicts an exemplary handoff control system of the exemplary WLAN of fig. 2.

Fig. 4 depicts one manner of configuring an exemplary subscriber station of the exemplary handoff control system of fig. 2.

Fig. 5 depicts one manner of configuring an exemplary Access Point (AP) of the exemplary handoff control system of fig. 2.

Fig. 6 depicts one manner of configuring an example AP controller of the example handoff control system of fig. 2.

Fig. 7 is a block diagram representing an example processor system of an example wireless communication platform that may be used to implement the example subscriber station of fig. 2.

Detailed Description

Methods and apparatus for providing a handover control system associated with a wireless communication network are generally described herein. The methods and apparatus described herein are not limited in this regard.

Referring to fig. 1, an exemplary wireless communication system 100 may include one or more wireless communication networks, shown generally at 110, 120, and 130. Specifically, the wireless communication system 100 may include a Wireless Personal Area Network (WPAN)110, a Wireless Local Area Network (WLAN)120, and a Wireless Metropolitan Area Network (WMAN) 130. Although fig. 1 depicts three wireless communication networks, the wireless communication system 100 may include more or fewer wireless communication networks. For example, the wireless communication system 100 may include additional WPANs, WLANs, and/or WMANs. The methods and apparatus described herein are not limited in this regard.

The wireless communication system 100 may also include one or more subscriber stations, shown generally as 140, 142, 144, 146, and 148. For example, subscriber stations 140, 142, 144, 146, and 148 may include wireless electronic devices such as a desktop computer, a laptop computer, a handheld computer, a tablet computer, a cellular telephone, a pager, an audio and/or video player (e.g., an mp3 player or a DVD player), a gaming device, a video camera, a digital camera, a navigation device (e.g., a GPS device), a wireless peripheral (e.g., a printer, a scanner, a headset, a keyboard, a mouse, etc.), a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), and/or other suitable fixed, portable, or mobile electronic devices. Although fig. 1 depicts five subscriber stations, the wireless communication system 100 may include more or fewer subscriber stations.

Each of subscriber stations 140, 142, 144, 146, and 148 may be authorized or allowed to access services provided by one or more wireless communication networks 110, 120, and/or 130. The subscriber stations 140, 142, 144, 146, and 148 may use a variety of modulation techniques, such as spread spectrum modulation (e.g., direct sequence code division multiple access (DS-CDMA) and/or frequency hopping code divisionMultiple access (FH-CDMA)), Time Division Multiplexing (TDM) modulation, Frequency Division Multiplexing (FDM) modulation, Orthogonal Frequency Division Multiplexing (OFDM) modulation (e.g., Orthogonal Frequency Division Multiple Access (OFDMA)), multi-carrier modulation (MDM), and/or other suitable modulation techniques to communicate over a wireless link. In one example, the laptop computer 140 may operate according to a suitable wireless communication protocol that requires little power, such as BluetoothUltra Wideband (UWB), and/or Radio Frequency Identification (RFID), thereby implementing WPAN 110. In particular, the laptop computer 140 may communicate with devices associated with the WPAN 110 (e.g., the camera 142 and/or the printer 144) via wireless links.

In another example, the laptop computer 140 may implement the WLAN 120 using Direct Sequence Spread Spectrum (DSSS) modulation and/or Frequency Hopping Spread Spectrum (FHSS) modulation (e.g., the 802.11 family of standards developed by the Institute of Electrical and Electronics Engineers (IEEE) and/or variations and evolutions of these standards). For example, laptop computer 140 may communicate with devices associated with WLAN 120 (e.g., printer 144, handheld computer 146, and/or smart phone 148) via a wireless link. The laptop computer 140 may also communicate with an Access Point (AP)150 via a wireless link. The AP150 is operatively coupled to a router 152, which will be described in detail below. Alternatively, AP150 and router 152 may be integrated into a single device (e.g., a wireless router).

The laptop computer 140 may transmit large amounts of digital data by dividing a radio frequency signal into multiple smaller sub-signals using OFDM modulation and then transmitting the sub-signals simultaneously at different frequencies. In particular, the laptop computer 140 utilizes OFDM modulation to implement the WMAN 130. For example, the laptop computer 140 operates in accordance with the 802.16 family of standards, which is introduced by the IEEE and provides fixed, portable, and/or mobile Broadband Wireless Access (BWA) networks (e.g., the IEEE802.16-2004 standard (published 2004, 9, 18), the IEEE802.16 e standard (published 2006, 2, 28), the IEEE802.16 f standard (published 2005, 12, 1), etc.) to communicate with base stations (shown generally at 160, 162, and 164) via wireless links.

Although some of the above examples are described in connection with standards developed by IEEE, the methods and apparatus disclosed herein are also readily applicable to many specifications and/or standards of other groups of specific interest and/or standard development organizations (e.g., wireless-fidelity (Wi-Fi) alliance, Worldwide Interoperability for Microwave Access (WiMAX) forum, infrared data standards association (IrDA), third generation partnership project (3GPP), etc.). The methods and apparatus described herein are not limited in this regard.

The WLAN 120 and WMAN 130 may be operatively coupled to a common public or private network 170 such as the internet, a telephone network (e.g., the Public Switched Telephone Network (PSTN)), a Local Area Network (LAN), a wired network, and/or other wireless networks connected to an ethernet, a Digital Subscriber Line (DSL), a telephone line, a coaxial cable, and/or other wireless connections, etc. In one example, the WLAN 120 may be operatively coupled to a common public or private network 170 through the AP150 and/or the router 152. As another example, the WMAN 130 may be operatively coupled to a common public or private network 170 via the base stations 160, 162, and/or 164.

The wireless communication system 100 may include other suitable wireless communication networks. For example, the wireless communication system 100 may include a Wireless Wide Area Network (WWAN) (not shown). The laptop computer 140 operates in accordance with other wireless communication protocols that support a WWAN. In particular, the wireless communication protocols are based on analog, digital, and/or dual-mode communication system technologies such as global system for mobile communications (GSM) technology, Wideband Code Division Multiple Access (WCDMA) technology, General Packet Radio Service (GPRS) technology, Enhanced Data GSM Environment (EDGE) technology, Universal Mobile Telecommunications System (UMTS) technology, third generation partnership project (3GPP) technology, standards, variations, evolutions of these technologies, and/or other suitable wireless communication standards. Although fig. 1 depicts only one WPAN, one WLAN, and one WMAN, wireless communication system 100 may include other combinations of WPANs, WLANs, WMANs, and/or WWANs. The methods and apparatus described herein are not limited in this regard.

Wireless communication system 100 may include other WPAN, WLAN, WMAN, and/or WWAN devices (not shown), such as network interface devices and peripherals (e.g., Network Interface Cards (NICs)), Access Points (APs), redistribution points, endpoints, gateways, bridges, hubs, etc., through which a cellular telephone system, a satellite system, a Personal Communication System (PCS), a two-way radio system, a one-way paging system, a two-way paging system, a Personal Computer (PC) system, a Personal Digital Assistant (PDA) system, a Personal Computing Assistant (PCA) system, and/or other suitable communication system may be implemented. Although certain examples have been described above, the scope of coverage of this patent is not limited thereto.

In the example of fig. 2, wireless communication network 200 may include a user Station (STA)210 and one or more Access Points (APs), shown generally at 220, 222, and 224. The wireless communication network 200 also includes an AP controller 230 operatively coupled to the APs 220, 222, and 224. For example, the wireless communication network 200 may be a WLAN operating in accordance with the IEEE802.11 family of standards and/or variations and evolutions of these standards, such as the IEEE802.11 task group k (radio resource measurement enhancements), the IEEE802.11 task group r (fast roaming/fast BSS transitions), and/or the IEEE802.11 task group v (radio network management). Although fig. 2 depicts a WLAN, the methods and apparatus described herein may be readily applied to other types of wireless communication networks, such as WPAN, WMAN, WWAN, and/or wireless mesh networks. In one example, wireless communication network 200 may be a WMAN or WWAN with one or more base stations instead of APs. Further, although fig. 2 depicts a single subscriber station, the wireless communication network 200 may include additional subscriber stations. Even though fig. 2 depicts three APs, the wireless communication network 200 may include additional APs.

In general, the subscriber station 210 may be any one of, or any combination of, the wireless electronic devices described in conjunction with FIG. 1. The subscriber station 210 may include a Network Interface Device (NID)240, an event recorder 250, a handoff monitor 260, a configuration regulator 270, a request generator 280, and a memory 285. The NID 240, the event recorder 250, the switch monitor 260, the configuration regulator 270, the request generator 280, and the memory 285 are operatively coupled to one another via a bus 290. Although fig. 2 depicts one or more components of the subscriber station 210 as being coupled to one another via the bus 290, these components may be operatively coupled to one another via other suitable direct or indirect connections (e.g., a point-to-point connection or a point-to-multipoint connection).

The NID 240 may include a receiver 242, a transmitter 244, and an antenna 246. For example, NID 240 may be a network interface card. The subscriber station 210 may receive and/or transmit data via the receiver 242 and the transmitter 244, respectively. Antenna 246 may include one or more directional or omnidirectional antennas, such as dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas and/or other types of antennas suitable for transmission of Radio Frequency (RF) signals. Although fig. 2 depicts a single antenna, the subscriber station 210 may include additional antennas. For example, the subscriber station 210 may include multiple antennas to implement a multiple-input multiple-output (MIMO) system.

The event recorder 250 may record information related to one or more transition events of the subscriber station 210. In each transition event, the subscriber station 210 may transition between two nodes (e.g., a handoff or transition of the subscriber station 210 from one AP to another AP). For convenience, the terms "handoff" and "transition" that refer to the transition of a connection of a subscriber station from one AP to another AP are used interchangeably throughout. In one example, the subscriber station 210 may transition or roam from the AP220 to the AP222 because the subscriber station 210 may move out of the coverage area of the AP220 and into the coverage area of the AP 222. Additionally or alternatively, the AP220 may be operating at full capacity, so that connections to the subscriber stations 210 may be transferred to neighboring APs (e.g., AP 222) of the AP 220. Accordingly, the switching of the connection of the subscriber station 210 may occur between the AP220 and the AP 222. In another example, the subscriber station 210 may transition or roam from AP220 to AP 224. The switching of the connection of the subscriber station 210 may occur between the AP220 and the AP 222.

The handoff monitor 260 may monitor a status (e.g., hard handoff, soft handoff, softer handoff, etc.) indicating that the subscriber station 210 is frequently handed off. In one example, the handoff monitor 260 may monitor one or more transition events of the subscriber station 210 over a period of time. If a predetermined number of transition events occur within the time period (e.g., five transition events occur within one minute), the switching monitor 260 may detect a status indicating that the subscriber station 210 switches frequently. For example, the switch monitor 260 may determine whether the number of transition events within the time period exceeds a predetermined threshold.

To avoid frequent handovers, the configuration adjustor 270 may adjust one or more configurations of the subscriber station 210, such as transmit power, roaming hysteresis, receive sensitivity, and/or clear channel assessment. In one example, the configuration adjuster 270 may adjust the roaming hysteresis amount of the subscriber station 210 if a condition indicating frequent handovers of the subscriber station 210 is detected. In particular, the configuration adjuster 270 may determine whether a signal strength between a signal transmitted from an AP (e.g., AP 220) in communication with the subscriber station 210 and a signal transmitted from a roaming candidate AP (e.g., AP 222) that provides wireless communication service to the subscriber station 210 is different. For example, the configuration adjustor 270 may increase the amount of roaming hysteresis for the subscriber station 210 by increasing the roaming hysteresis threshold. Thus, the subscriber station 210 may require that the signal strengths of the multiple signals received by the subscriber station 210 differ significantly before transitioning from one AP to another AP. In addition, configuration adjuster 270 may also adjust one or more configurations based on configuration information from AP220 and/or AP controller 230, as will be described in detail below.

The request generator 280 may generate a roaming management request including transition event information associated with a transition event of the subscriber station 210. For example, the transition event information may include transition identification information, transition timestamp information, transition cause information, target identification information, source identification information, Received Signal Strength Indicator (RSSI) information, received signal to noise ratio indicator (RSNI) information, transmit power information, roaming hysteresis information, receive sensitivity information, or Clear Channel Assessment (CCA) information associated with each transition event of the subscriber station 210.

Typically, the conversion identification information identifies each conversion event. The conversion timestamp information indicates the time (e.g., date and/or time) at which each conversion event occurred. The conversion cause information indicates the cause of occurrence of each conversion event. The target identification information and the source identification information indicate the target AP and the source AP (e.g., BSSIDs of the target AP and the source AP) for each transition event. The RSSI information indicates the strength of the signal received at the subscriber station 210 from the target AP for each transition event. The RSNI information represents the signal-to-noise ratio received at the subscriber station 210 from the source AP for each transition event.

The transmit power information represents the transmit power associated with the subscriber station 210 transmitting signals to the target AP and the source AP for each transition event. The roaming hysteresis information represents the signal strength difference between the signal transmitted from the target AP and the signal transmitted from the source AP for each transition event. The receive sensitivity information represents the receive power associated with the subscriber station 210 receiving signals from each of the target AP and the source AP for each transition event. The CCA information represents a CCA associated with each of the target AP and the source AP for each transition event. The CCA threshold may account for noise and/or interference associated with the channel. To determine whether a particular channel is available, the subscriber station 210 may determine whether the received power associated with signals passing through the channel is less than the CCA threshold. If the received power is less than the CCA threshold, then the particular channel is available to the subscriber station 210.

In one example, the request generator 280 may generate a roaming management request after the configuration adjustor 270 adjusts the roaming hysteresis amount of the subscriber station 210, but the handoff monitor 260 still detects a state indicating that the subscriber station 210 is frequently handed off. Accordingly, the NID 240 sends a roaming management request to the AP 220. Based on the transition event information, AP220 may adjust one or more configurations of AP 220. In one example, AP220 may adjust the amount of roaming hysteresis for AP 220. AP220 may forward the transition event information to AP controller 230. Specifically, the AP220 may generate a request for avoiding frequent handover including the transition event information. Based on the transition event information, AP controller 230 may adjust one or more configurations of an AP (e.g., AP 220) in communication with subscriber station 210 and/or one or more neighboring APs (e.g., APs 222 and/or 224) of the AP in communication with subscriber station 210. For example, AP controller 230 may adjust transmit power, roaming hysteresis, receive sensitivity, and/or clear channel assessment for APs 220, 222, and/or 224.

Additionally or alternatively, the AP controller 230 may provide recommendations to the subscriber station 210 to reduce the number of transition events over a period of time. The AP controller 230 may generate configuration information to adjust one or more configurations of the subscriber station 210, such as transmit power, roaming hysteresis, receive sensitivity, clear channel assessment, or roaming candidate nodes. In one example, AP controller 230 generates and sends a frequent handover avoidance response including configuration information to AP 220. The AP220 may then generate and transmit a roaming management response including the configuration information to the subscriber station 210. Based on the configuration information, the configuration adjustor 270 adjusts one or more configurations of the subscriber station 210 to reduce the number of transition events over a period of time.

Although the components shown in fig. 2 are depicted as separate blocks within the subscriber station 210, the functions performed by some of these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits. In one example, although the receiver 242 and the transmitter 244 are described as separate modules in the NID 240, the receiver 242 may be integrated into the transmitter 244 (e.g., a transceiver). In another example, the event recorder 250, the switch monitor 260, the configuration adjustor 270, and/or the request generator 280 may be integrated into a single component. In addition, certain modules within the subscriber station 210 may be integrated into a Network Interface Card (NIC) (not shown). For example, the NID 240, the event recorder 250, the handoff monitor 260, the configuration regulator 270, and/or the request generator 280 may be integrated into a NIC.

Access points 220, 222, and 224 may be associated with the same wireless communication network or different wireless communication networks. As described in detail below, the subscriber station 210 may be connected to two or more wireless communication networks simultaneously or concurrently. Although fig. 2 depicts one or more Basic Service Set (BSS) networks, the methods and apparatus described herein may be readily applied to other suitable networks, such as Independent Basic Service Set (IBSS) networks. Further, while the above examples are described with respect to an AP and an AP controller associated with a WLAN, the methods and apparatus described herein may be readily applied to Base Stations (BSs) and BS controllers associated with WMANs and/or WWANs and/or subscriber stations associated with a wireless mesh network. The methods and apparatus described herein are not limited in this regard.

In general, frequent handoffs of the subscriber station 210 between multiple APs increases network burden because the subscriber station 210 needs to re-associate and re-generate keys when transitioning from one AP or roaming to another AP. In addition, frequent switching by the subscriber station 210 may cause interruptions, reduce quality of service, and/or increase jitter in the data, voice, and/or video streams.

In the example of fig. 3, handoff control system 300 may include a subscriber station (e.g., subscriber station 210 in fig. 2) and an AP (e.g., AP220 in fig. 2). Handoff control system 300 may also include an AP controller (e.g., AP controller 230 in fig. 2). Alternatively, AP controller 230 may be integrated into AP220, or handoff control system 300 may not include AP controller 230.

To illustrate the handover control system 300, the subscriber station 210 may record information related to transition events of the subscriber station 210 and monitor a status indicating frequent handovers. In particular, the subscriber station 210 may determine whether the number of transition events over a period of time exceeds a predetermined threshold. In one example, five transition events within one minute represent frequent switching.

If the subscriber station 210 detects a condition indicating frequent handoffs, the subscriber station 210 may increase the roaming hysteresis amount to maintain contact with the AP220, rather than going to another AP (e.g., AP222 or 224 in fig. 2). As described above, the roaming hysteresis amount represents a signal strength difference between a signal transmitted from an AP (e.g., AP 220) communicating with the subscriber station 210 and a signal transmitted from another AP (e.g., AP 222). For example, by increasing the amount of roaming hysteresis, the subscriber station 210 may reduce frequent handovers because the difference in signal strength between the signal from the AP220 and the signal from the AP222 becomes large before the subscriber station 210 is to switch from the AP220 to the AP 222.

However, if the subscriber station 210 still detects a state indicating frequent handover after increasing the roaming hysteresis amount, the subscriber station 210 may forward the transition event information to the AP 220. In one example, the subscriber station 210 may generate a roaming management request including the transition event information and transmit the roaming management request to the AP220 (310). Next, the AP220 may generate an avoid frequent handover request to forward the transition event information to the AP controller 230 (320).

Based on the transition event information, AP controller 230 may adjust the configuration of one or more APs (e.g., APs 222 and/or 224 in fig. 2) that are proximate to AP 220. AP controller 230 may also adjust roaming hysteresis associated with AP 220. In addition, the AP controller 230 may provide recommendations to the subscriber station 210 to avoid frequent handovers. Specifically, the AP controller 230 may generate and send a avoid frequent handover response to the AP220 (330). The avoid frequent handover response may include configuration information. Specifically, the configuration information may include information related to a transmit power setting, a reception sensitivity, and/or a CCA threshold suggested by the AP controller 230 to the subscriber station 210. The configuration information may also include information relating to one or more candidates where the AP controller 230 suggests to the subscriber station 210 to roam and connect to for wireless communication services.

Accordingly, the AP220 may generate a roaming management response based on the avoid frequent handover response from the AP controller 230 (340). In addition to the configuration information and candidate information described above, the AP220 may also include information related to roaming hysteresis in the roaming management response. That is, the AP220 may suggest to the subscriber station 210 to adjust the amount of roaming hysteresis. Based on the roaming management response from AP220, subscriber station 210 may adjust one or more configurations and/or switch to another AP (e.g., AP222 or AP 224). The methods and apparatus described herein are not limited in this regard.

Fig. 4, 5 and 6 depict one manner in which the handoff control system 300 of fig. 3 may be configured to detect and mitigate frequent handoffs. The example processes 400, 500, and 600 of fig. 4, 5, and 6, respectively, may be implemented as machine-accessible instructions using any of a number of different program code stored on any combination of machine-accessible media such as a volatile or non-volatile memory or other mass storage device (e.g., a floppy disk, a CD, and a DVD). For example, the machine-accessible instructions may be embodied in a machine-accessible medium such as a programmable gate array, an Application Specific Integrated Circuit (ASIC), an erasable programmable read-only memory (EPROM), a read-only memory (ROM), a random-access memory (RAM), flash memory, a magnetic medium, an optical medium, and/or any other suitable type of medium.

Further, while a particular order of acts is shown in each of fig. 4, 5, and 6, these acts may be performed in other temporal sequences (e.g., concurrently or concurrently). Furthermore, the exemplary processes 400, 500, and 600 described and provided in connection with the wireless communication network of fig. 2 are merely examples of one way to provide a handover control system.

In the example of fig. 4, the process 400 may begin with the subscriber station 210 recording (e.g., via the event recorder 250 of fig. 2) information related to one or more transition events (block 410). Event recorder 250 may store information (e.g., statistics) related to the transition events in memory 285.

As described above, during each transition event (e.g., the subscriber station 210 switching from one AP to another AP), the subscriber station 210 may transition between the two APs. To reduce network load and increase quality of service, the subscriber station 210 may monitor a status indicating frequent handovers. In particular, the subscriber station 210 (e.g., via the handoff monitor 260 of fig. 2) may monitor the number of transition events over a period of time and determine whether the number of transition events exceeds a predetermined handoff threshold (block 420).

If the number of transition events does not exceed the predetermined switching threshold, control may return to block 410 to continue recording information related to the transition events. Otherwise, if the number of transition events exceeds the predetermined handoff threshold at block 420, the subscriber station 210 (e.g., via the configuration adjuster 270 of fig. 2) may determine whether to adjust the roaming hysteresis amount of the subscriber station 210 (block 430).

If the subscriber station 210 has not previously adjusted the roaming delay, the subscriber station 210 (e.g., by configuring the adjustor 270) may increase the roaming delay threshold (block 440). Accordingly, control may return to block 410 to record information related to the transition event.

Referring again to block 430, if the subscriber station 210 has previously adjusted the roaming hysteresis, the subscriber station 210 (e.g., via the request generator 280 of fig. 2) may generate a roaming management request (block 450). The roaming management request may include transition event information. As described above, the transition event information may include transition identification information, transition timestamp information, transition cause information, target identification information, source identification information, RSSI information, RSNI information, transmit power information, roaming hysteresis information, reception sensitivity information, or CCA information associated with each transition event of the subscriber station 210.

Because the AP220 is communicating with and providing service to the subscriber station 210, the subscriber station 210 (e.g., via the NID 240 of fig. 2) may send a roaming management request to the AP220 (block 460). Thus, the subscriber station 210 may monitor for a roaming management response from the AP220 (block 470). As described in detail below in conjunction with fig. 5, the AP220 may generate a roaming management response based on a roaming management request from the subscriber station 210.

Referring to fig. 5, process 500 may begin, for example, with AP220 receiving a roaming management request from a subscriber station 210 (block 510). As described above, the roaming management request may include transition event information. Based on the transition event information, the AP220 may generate an avoid frequent handoff request (block 520). In particular, the avoidance of frequent handover requests may include transition event information from the subscriber station 210. The avoidance of frequent handoff requests may also include information related to AP220 such as transmit power, receive sensitivity, and/or CCA of AP 220. Accordingly, AP220 may send an avoid frequent handoff request to AP controller 230 (block 530). As described in detail below in connection with fig. 6, AP controller 230 may generate an avoid frequent switching response based on an avoid frequent switching request from AP 220.

In the example of fig. 6, process 600 may begin with AP controller 230 receiving a request from AP220 to avoid frequent handovers (block 610). As described above, the avoidance of frequent handoff requests may include transition event information from the subscriber station 210 and/or other suitable information from the AP 220. Based on the transition event information, AP controller 230 may adjust the configuration of one or more APs, such as APs 220, 222, and/or 224 (block 620). In one example, AP controller 230 may adjust a configuration, such as transmit power, receive sensitivity, and/or CCA, of one or more neighboring APs (e.g., APs 222 and/or 224) of AP 220.

The AP controller 230 may also provide recommendations to adjust one or more configurations of the subscriber station 210 to reduce frequent handovers. Additionally or alternatively, the AP controller 230 may suggest roaming candidate APs to which the subscriber station 210 may switch such that the subscriber station 210 may avoid frequent switching. Specifically, the AP controller 230 may generate an avoid frequent handover response (block 630). For example, the avoid-frequent-handover response may include configuration information, such as transmit power information, receive sensitivity information, and/or CCA information. The configuration information indicates roaming candidate APs to which the subscriber station 210 can transition for the wireless communication service. Accordingly, AP controller 230 may send an avoid frequent switch response to AP220 (block 640).

Although the above examples are described in connection with an AP controller, the functions described in connection with process 600 may be performed by an AP, such as AP 220. Further, although the above examples are described in connection with a WLAN, the methods and apparatus described herein may be implemented in other suitable wireless communication networks, such as a wireless mesh network having a plurality of subscriber stations. In particular, the functions described in connection with process 600 may be performed by one or more subscriber stations of a plurality of subscriber stations. The methods and apparatus described herein are not limited in this regard.

Referring back to fig. 5, the AP220 may receive a frequent handover avoidance response from the AP controller 230 (block 540). As described above, the avoid frequent handover response may include configuration information of the subscriber station 210 and/or the AP 220. Based on the avoid frequent handover response, AP220 may generate a roaming management response (block 550). In one example, the roaming management response may include configuration information for the subscriber station 210. Accordingly, the AP220 may transmit a roaming management response to the subscriber station 210 (block 560). The methods and apparatus described herein are not limited in this regard.

Referring again to block 470 of fig. 4, if the subscriber station 210 does not receive a roaming management response from the AP220, control may continue to monitor for a roaming management response. Otherwise, if the subscriber station 210 receives the roaming management response, the subscriber station 210 (e.g., via the configuration adjuster 270) may adjust one or more configurations of the subscriber station 210 based on the roaming management response (block 480). As described above, the roaming management response may include configuration information of the subscriber station 210. In one example, the subscriber station 210 may adjust transmit power, roaming hysteresis, receive sensitivity, and/or CCA. The configuration information may also include information related to roaming candidates. Thus, the subscriber station 210 can reduce the frequency of handover. The methods and apparatus described herein are not limited in this regard.

Although the above examples are described in connection with an AP controller, the methods and apparatus described herein may be implemented without an AP controller or with an AP controller integrated within an AP. Referring again to fig. 2 and 3, the AP220 may receive transition event information from the subscriber station 210 as described above. Instead of forwarding the transition event information to the AP controller (e.g., 320 of fig. 3), the AP220 may adjust one or more configurations associated with the AP220 and/or the subscriber station 210. In one example, AP220 may increase the transmit power of AP220 to expand the coverage area of AP220 and/or to cover one or more relatively weak portions of the coverage area. The AP220 may also increase the amount of roaming hysteresis for the subscriber station 210 so that the subscriber station 210 may remain at the AP220 rather than going to another AP (e.g., AP 230 or 240 of fig. 2). The AP220 may also suggest adjustments to one or more configurations associated with the subscriber station 210. For example, the AP220 may suggest adjustments to transmit power, receive sensitivity, and/or CCA associated with the subscriber station 210.

Further, although the above examples are described in connection with a WLAN, the methods and apparatus described herein may be implemented in other suitable types of wireless communication networks, such as WPANs, WMANs, WWANs, and/or wireless mesh networks. The methods and apparatus described herein are not limited in this regard.

Fig. 7 is a block diagram of an example processor system 2000 adapted to implement the methods and apparatus disclosed herein. The processor system 2000 may be a desktop computer, a laptop computer, a handheld computer, a tablet computer, a Personal Digital Assistant (PDA), a server, an internet application, and/or any other type of computing device.

The processor system 2000 represented in fig. 7 may include a chipset 2010, which includes a memory controller 2012 and an input/output (I/O) controller 2014. The chipset 2010 may provide memory and I/O management functions as well as a plurality of general purpose and/or special purpose registers, timers, etc. that are accessible or used by a processor 2020. The processor 2020 may be implemented using one or more processors, WPAN components, WLAN components, WMAN components, WWAN components, and/or other suitable processing components. For example, processor 2020 may utilize IntelCore^TMTechnique, IntelPentiumTechnique, IntelItaniumTechnique, IntelCentrino^TMTechnology and/or IntelXeon^TMOne or more of the techniques. Alternatively, the processor 2020 may be implemented using other processing technologies. The processor 2020 may include a cache 2022, which may be implemented using a level one unified cache (L1), a level two unified cache (L2), a level three unified cache (L3), and/or any other suitable structure for storing data.

The memory controller 2012 may perform functions that enable the processor 2020 to access and communicate with a main memory 2030 via a bus 2040, the main memory 2030 including a volatile memory 2032 and a non-volatile memory 2034. The volatile memory 2032 may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM), Static Random Access Memory (SRAM), and/or any other type of random access memory device. The non-volatile memory 2034 may be implemented by flash memory, Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), and/or any other desired type of memory device.

The processor system 2000 may also include an interface circuit 2050 that is coupled to the bus 2040. The interface circuit 2050 may be implemented using any type of interface standard such as an ethernet interface, a Universal Serial Bus (USB), a third generation input/output (3GIO) interface, and/or any other suitable type of interface.

One or more input devices 2060 may be connected to the interface circuit 2050. The input device(s) 2060 permit an individual to enter data and commands into the processor 2020. For example, the input device 2060 may be implemented by a keyboard, a mouse, a touch-sensitive display, a track pad, a track ball, an equivalent point, and/or a voice recognition system.

One or more output devices 2070 may also be connected to the interface circuit 2050. For example, the output device(s) 2070 may be implemented by display devices (e.g., a Light Emitting Display (LED), a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT) display, a printer and/or speakers). In addition, the interface circuit 2050 may include a graphics driver card.

The processor system 2000 may also include one or more mass storage devices 2080 to store software and data. Examples of such mass storage devices 2080 include floppy disks and drives, hard disk drives, optical disks and drives, and Digital Versatile Disks (DVD) and drives.

The interface circuit 2050 may also include a communication device such as a modem or a network interface card to facilitate exchange of data with external computers via a network. The communication link between the processor system 2000 and the network may be any type of network connection such as an ethernet connection, a Digital Subscriber Line (DSL), a telephone line, a cellular telephone system, a coaxial cable, etc.

Access to the input device(s) 2060, the output device(s) 2070, the mass storage device(s) 2080 and/or the network may be controlled by the I/O controller 2014. In particular, the I/O controller 2014 may perform functions that enable the processor 2020 to communicate with the input device(s) 2060, the output device(s) 2070, the mass storage device(s) 2080 and/or the network via the bus 2040 and the interface circuit 2050.

Although the components shown in fig. 7 are depicted as separate blocks within the processor system 2000, the functions performed by some of these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits. For example, although the memory controller 2012 and the I/O controller 2014 are depicted as separate blocks within the chipset 2010, the memory controller 2012 and the I/O controller 2014 may be integrated within a single semiconductor circuit.

Although certain example methods, apparatus, and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. For example, although the exemplary system disclosed above includes other components in addition to software or firmware executed on hardware, it should be understood that the system is merely illustrative and not limiting. In particular, some or all of the hardware, software, and/or firmware disclosed herein may be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and/or firmware.

Claims (24)

1. A method associated with a wireless communication network, comprising the steps of:

monitoring, by a subscriber station, a plurality of transition events over a period of time, the subscriber station transitioning between two nodes of a plurality of nodes associated with the wireless communication network during each transition event;

determining, by the subscriber station, that the plurality of transition events monitored during the time period has exceeded a predetermined threshold;

generating, by the subscriber station, a roaming management request having transition event information associated with the plurality of transition events; and

transmitting, by the subscriber station, the roaming management request to a node of the wireless communication network to enable the node to adjust one or more configurations of the node to further reduce transition events for the subscriber station.

2. The method of claim 1, wherein generating the roaming management request comprises: a request is generated having information associated with at least one of a transition identification, a transition timestamp, a reason for the transition, a target identification, a source identification, a received signal strength indicator, a received signal to noise ratio indicator, a transmit power, a roaming hysteresis, a receive sensitivity, or a clear channel assessment for each of the plurality of transition events.

3. The method of claim 1, further comprising: recording information associated with each of the plurality of transition events to generate the transition event information.

4. The method of claim 1, further comprising: increasing a roaming hysteresis amount of the subscriber station before generating the roaming management request.

5. The method of claim 1, wherein the transmitting step comprises: sending the roaming management request to at least one of: an access point associated with a wireless local area network, a base station associated with a wireless metropolitan area network, a base station associated with a wireless wide area network, or another subscriber station associated with a wireless mesh network.

6. The method of claim 1, further comprising: receiving a roaming management response from one of the plurality of nodes in communication with the subscriber station, the roaming management response having configuration information that causes the subscriber station to reduce handovers by the subscriber station.

7. The method of claim 1, further comprising: adjusting one or more configurations of the subscriber station to reduce handoff of the subscriber station based on configuration information from a roaming management response from a node in communication with the subscriber station, the configuration information having information associated with at least one of transmit power, roaming hysteresis, receive sensitivity, clear channel assessment, or roaming candidates.

8. An apparatus associated with a wireless communication network, comprising:

means for monitoring a plurality of transition events for a subscriber station over a period of time, the subscriber station transitioning between two or more nodes of a plurality of nodes associated with the wireless communication network during each transition event;

means for determining that the plurality of transition events monitored during the time period has exceeded a predetermined threshold;

means for generating a roaming management request at the subscriber station, the roaming management request having transition event information associated with the plurality of transition events; and

means for sending the roaming management request to a node of the wireless communication network to enable the node to adjust one or more configurations of the node to further reduce transition events.

9. The apparatus of claim 8, further comprising:

means for generating the roaming management request by generating a request with information associated with at least one of a transition identification, a transition timestamp, a reason for transition, a target identification, a source identification, a received signal strength indicator, a received signal to noise ratio indicator, a transmit power, a roaming hysteresis, a receive sensitivity, or a clear channel assessment for each transition event of the plurality of transition events.

10. The apparatus of claim 8, further comprising:

means for increasing a roaming hysteresis amount of the subscriber station prior to generating the roaming management request.

11. The apparatus of claim 8, further comprising:

for sending the roaming management request to at least one of: means for accessing a wireless local area network, a base station associated with a wireless metropolitan area network, a base station associated with a wireless wide area network, or another subscriber station associated with a wireless mesh network.

12. The apparatus of claim 8, further comprising:

means for receiving a roaming management response from one of the plurality of nodes in communication with the subscriber station, the roaming management response having configuration information that causes the subscriber station to reduce handovers of the subscriber station.

13. The apparatus of claim 8, further comprising:

means for adjusting one or more configurations of the subscriber station to reduce handoff of the subscriber station based on configuration information of a roaming management response from a node in communication with the subscriber station, the configuration information having information associated with at least one of transmit power, roaming hysteresis, receive sensitivity, clear channel assessment, or roaming candidates.

14. An apparatus associated with a wireless communication network, comprising:

a transition monitor to monitor a plurality of transition events for a subscriber station during a time period during which the subscriber station transitions between two or more of a plurality of nodes associated with the wireless communication network and to determine that the plurality of transition events monitored during the time period have exceeded a predetermined threshold;

a request generator operatively coupled to the transition monitor to generate a roaming management request at the subscriber station, the roaming management request having transition event information associated with the plurality of transition events; and

a network interface device, operatively coupled to the request generator, for sending the roaming management request to a node of the wireless communication network to enable the node to adjust one or more configurations of the node to further reduce transition events for the user equipment.

15. The apparatus of claim 14, wherein the request generator is configured to generate a request having information associated with at least one of a transition identification, a transition timestamp, a transition cause, a target identification, a source identification, a received signal strength indicator, a received signal-to-noise indicator, a transmit power, a roaming hysteresis, a receive sensitivity, or a clear channel assessment for each of the plurality of transition events.

16. The apparatus of claim 14, wherein the network interface device is configured to send the roaming management request to at least one of: an access point associated with a wireless local area network, a base station associated with a wireless metropolitan area network, a base station associated with a wireless wide area network, or another subscriber station associated with a wireless mesh network.

17. The apparatus of claim 14, wherein the network interface device is configured to receive a roaming management response from one of the plurality of nodes in communication with the subscriber station, the roaming management response having configuration information that causes the subscriber station to reduce handovers of the subscriber station.

18. The apparatus of claim 14, further comprising: a configuration adjustor for increasing a roaming hysteresis amount of the subscriber station before the request generator generates the roaming management request.

19. The apparatus of claim 14, further comprising: a configuration adjuster that adjusts one or more configurations of the subscriber station based on configuration information from a roaming management response from a node in communication with the subscriber station, the configuration information having information associated with at least one of transmit power, roaming hysteresis, receive sensitivity, clear channel assessment, or roaming candidates, so as to reduce handovers by the subscriber station.

20. A method associated with a wireless communication network, comprising:

receiving, by a node controller, an avoid frequent handover request from one of a plurality of nodes associated with the wireless communication network, wherein the avoid frequent handover request includes transition event information associated with a plurality of transition events for a subscriber station transitioning between two of the plurality of nodes associated with the wireless communication network during each transition event;

adjusting, by the node controller, one or more neighboring nodes of the plurality of nodes associated with the wireless communication network, wherein the neighboring nodes are neighbors of a node currently serving the subscriber station; and

configuration information for the subscriber station is generated to adjust one or more configurations of the subscriber station.

21. The method of claim 20, wherein adjusting the one or more neighboring nodes comprises: adjusting at least one of transmit power, roaming hysteresis, receive sensitivity, or clear channel assessment of the one or more neighboring nodes.

22. The method of claim 20, further comprising: generating an avoid frequent handover response having configuration information of at least one of the subscriber station, a node in communication with the subscriber station, or a neighbor node of the node in communication with the subscriber station.

23. The method of claim 20, further comprising: transmitting the configuration information to the subscriber station with a roaming management response, the configuration information having information associated with at least one of transmit power, roaming hysteresis, receive sensitivity, clear channel assessment, or roaming candidates.

24. The method of claim 20, wherein the plurality of nodes comprises at least one of: an access point associated with a wireless local area network, a base station associated with a wireless metropolitan area network, a base station associated with a wireless wide area network, or another subscriber station associated with a wireless mesh network.