Patent Grant
9271196
The ability to perform a handover of a wireless device from one access node to another is a fundamental function of a wireless communication system. To maintain current data sessions and current voice sessions of the wireless device, communication session information for the wireless device is typically maintained in the communication network when a handover is performed. When the communication session information is not retained it will need to be redetermined, which can cause delay in the establishment of communication for the wireless device. Delay can also be caused by the release of signaling communication session information among network elements when a handover is performed, or when a wireless device leaves a coverage area of an access node and returns to the access node within a short period of time.
In operation, an application requirement is determined of an application running on a wireless device in communication with a first access node. A traffic class indicator associated with the wireless device is also determined. Further, a wireless communication link load of a communication link between the wireless device and the first access node is determined. A probability of performing a first handover of the wireless device to a second access node and a second handover of the wireless device from the second access node to the first access node within a predetermined period of time is also determined. Based on the application requirement, the traffic class indicator, the wireless communication link load, and the determined probability, a context maintenance time is calculated, and a timer is started using the context maintenance time when the first handover is performed. Communication session information related to the communication between the wireless device and the first access node is maintained until the timer expires. If the wireless device re-establishes communication with the first access node before the timer expires, the communication session information can be maintained until the re-established communication ends.
Access nodes 104 and 106 are each a network node capable of providing wireless communications to wireless device 102, and can be, for example, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Access node 104 is in communication with communication network 106 over communication link 114, and access node 106 is in communication with communication network 108 over communication link 116. Access nodes 104 and 106 can also communicate with each other over communication link 118. In an embodiment, access node 104 can be associated with a first radio access technology and access node 106 can be associated with a second radio access technology.
Communication network 108 can be a wired and/or wireless communication network, and can comprise processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Communication network 108 can be capable of carrying voice information and other data, for example, to support communications by a wireless device such as wireless device 102. Wireless network protocols may comprise code division multiple access (CDMA) 1xRTT, Global System for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Evolution Data Optimized (EV-DO), EV-DO rev. A, Worldwide Interoperability for Microwave Access (WiMAX), and Third Generation Partnership Project Long Term Evolution (3GPP LTE). Wired network protocols that may be utilized by communication network 108 comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Communication network 108 may also comprise a wireless network, including base stations, wireless communication nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof.
Communication links 110, 112, 114, 116 and 118 can be wired or wireless communication links. Wired communication links can comprise, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless communication links can comprise a radio frequency, microwave, infrared, or other similar signal, and can use a suitable communication protocol, for example, Global System for Mobile telecommunications (GSM), Code Division Multiple Access (CDMA), Worldwide Interoperability for Microwave Access (WiMAX), or Long Term Evolution (LTE), or combinations thereof. Other wireless protocols can also be used.
Other network elements may be present in communication system 100 to facilitate wireless communication but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between access node 104, access node 106 and communication network 108 which are omitted for clarity, including additional processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements.
When a wireless device is handed over from a first access node to a second access node, where both access nodes are associated with the same radio access technology, to maintain current data sessions and current voice sessions of the wireless device communication session information for the wireless device is typically maintained in the communication network. Communication session information can comprise context information and other information used by the communication network to enable control signaling and bearer data transfer for a communication session with a wireless device. However, when a wireless device changes from communicating with an access node using one radio access technology to communicating with another access node using a second radio access technology, some or all of the communication session information may not be retained. When the communication session information is not retained it will need to be redetermined, which can cause delay in the establishment of communication through the second access node. In addition, network connections among network elements require to support the communication session may also be released or lost, causing further delay in the establishment of communication through the second access node. Further, delay can also be caused by the release of communication session information and/or network element connections when a wireless device is handed over from the first access node to the second access node, and is then handed over back to the first access node within a predetermined period of time (such as so-called ping-ponging between access nodes). In such case, the release of communication session information related to the first access node can cause delay in the reestablishment of communication between the wireless device and the first access node.
In operation, for wireless device 102 in communication with first access node 104, an application requirement is determined of an application running on wireless device 102, and a traffic class indicator associated with wireless device 102 is also determined. In addition, a wireless communication link load of communication link 110 is determined. A probability of performing a first handover of wireless device 102 to second access node 106 and a second handover of wireless device 102 from second access node 106 to first access node 104 within a predetermined period of time is also determined. Based on the application requirement, the traffic class indicator, the wireless communication link load, and the determined probability, a context maintenance time is calculated, and a timer is started using the context maintenance time when the first handover is performed. The timer can be started at access node 104, or at another network element of communication system 100, such as a controller node, a gateway node, and the like. Communication session information related to the communication between the wireless device and the first access node is maintained until the timer expires. If the wireless device re-establishes communication with the first access node before the timer expires, the communication session information can be maintained until the re-established communication ends.
The application requirement can comprise, for example, a minimum data rate, a minimum throughput, a maximum permitted data error rate, a maximum permitted packet loss rate, and the like, required by the application to provide a minimum level of performance. The traffic class indicator can comprise a threshold level of priority associated with bearer data being sent from a wireless device, such as a quality of service class indicator (QCI) or similar traffic class indicator. The wireless communication link load can comprise a level of wireless resource utilization, such as a utilization of physical resource blocks or other units of resource allocation, a level of demand for communication link resources, a level of requested wireless communication link resources (such as by a buffer status report or other request for communication link resources), a number of wireless devices in active communication with the first access node, and the like.
Next, the probability of performing a first handover of the wireless device to a second access node and a second handover of the wireless device from the second access node to the first access node within a predetermined period of time is determined (operation 204). Performing handovers of a wireless device between two access nodes within a relatively short period of time (so-called ping ponging) can be triggered, for example, when signal levels received by wireless device 102 from access nodes 104 and 106 vary over time. Signal levels can comprise a signal strength (such as a received signal strength indicator (RSSI), a reference signal received power (RSRP), and the like), a signal quality (such as a received signal quality indicator (RSQI), a reference signal received quality (RSRQ), and so forth) and similar signal levels or signal level indicators Signal level variation can be caused by wireless device mobility, radio frequency interference, physical interference with the signal levels (such as by a physical obstruction, topographical feature, etc.) and the like. Signal levels can be monitored, and based on signal variation over time a probability of performing repeated handovers between access nodes can be determined. Access node mobility, such as direction of mobility, speed of mobility, and so forth, can also be used to determine the probability.
Additionally, or alternatively, the first access node can have a higher priority or handover preference than the second access node, which priority can also be used to determine the probability of ping ponging. For example, the first access node can use a first radio access technology which is given a higher priority than a second radio access technology used by the second access node. An example of such a case can be where the first radio access technology comprises LTE, WiMAX, or another 4G radio access technology, and the second radio access technology comprises CDMA or another 3G radio access technology, wherein the communication system places a priority on 4G radio access technology over 3G radio access technology. The priority can be imposed on an access node-level basis, or in a designated region, group of access nodes, tracking area, and so forth.
Based on the application requirement, the traffic class indicator, the wireless communication link load, and the determined probability, a context maintenance time is calculated (operation 206) Determining the context maintenance time according to the application requirement, the traffic class indicator, the wireless communication link load, and the determined probability enables the determination of a context maintenance time which is provides a quality of experience appropriate to the needs of the wireless device and the state of communication system 100, while avoiding the over-commitment of resources and/or network communication sessions to wireless device 102.
When the first handover is performed, a timer is started using the context maintenance time (operation 208). The timer can be started at access node 104 or at another element of communication system 100. Communication session information related to the communication between the wireless device and the first access node is maintained until the timer expires (operation 210). If the wireless device re-establishes communication with the first access node before the timer expires, the communication session information can be maintained until the re-established communication ends. By maintaining the communication session information until the timer expires, a delay in communication with wireless device 102 can be reduced when the wireless device is handed over between access nodes 104 and 106.
Access nodes 304 and 306 are each a network node capable of providing wireless communications to wireless device 302, and can be, for example, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Access node 304 is in communication with gateway node 308 over communication link 328, and with controller node 312 over communication link 322. Access node 306 is in communication with gateway node 310 over communication link 330, and with controller node 312 over communication link 324. Access nodes 304 and 306 can also communicate with each other over communication link 326. In an embodiment, access node 304 can be associated with a first radio access technology and access node 306 can be associated with a second radio access technology. In an embodiment, access node 304 and gateway node 308 can be associated with a first communication network, and access node 306 and gateway node 310 can be associated with a second network. While communication links 324 and 334 are illustrated between access node 306, controller node 312, and gateway node 310, in an embodiment access node 306 and gateway node 310 may be in communication with a separate controller node (not illustrated).
Gateway nodes 308 and 310 can each comprise a processor and associated circuitry to execute or direct the execution of computer-readable instructions, and can be configured to maintain network connection information associated with wireless device 302. Gateway nodes 308 and 310 can retrieve and execute software from storage, which can include a disk drive, flash drive, memory circuitry, or some other memory device, and which can be local or remotely accessible. The software comprises computer programs, firmware, or some other form of machine-readable instructions, and may include an operating system, utilities, drivers, network interfaces, applications, or some other type of software, including combinations thereof. Gateway nodes 308 and 310 can receive instructions and other input at a user interface. Examples of gateway nodes 308 and 310 can include a standalone computing device, a computer system, or a network component, such as an access service network gateway (ASN-GW), a packet data network gateway (P-GW), a serving gateway (S-GW), a mobile switching controller (MSC), a packet data serving node (PDSN), call processing equipment, a home agent, a radio node controller (RNC), a subscriber profile system (SPS), and an authentication, authorization, and accounting (AAA) equipment, including combinations thereof. Gateway node 308 is in communication with inspection node 314 over communication link 336, and with communication network 316 over communication link 316. Gateway node 310 is in communication with inspection node 314 over communication link 338, and with communication network 316 over communication link 342.
Controller node 312 can comprise can comprise a processor and associated circuitry to execute or direct the execution of computer-readable instructions, and can be configured to maintain network connection information associated with wireless device 302. Controller node 312 can control the setup and maintenance of a communication session over communication network 316 by wireless device 302. Controller node 312 can comprise a mobile switching center (MSC), a dispatch call controller (DCC), a mobility management entity (MME), or other similar network node. Controller node 312 can retrieve and execute software from storage, which can include a disk drive, flash drive, memory circuitry, or some other memory device, and which can be local or remotely accessible. The software comprises computer programs, firmware, or some other form of machine-readable instructions, and may include an operating system, utilities, drivers, network interfaces, applications, or some other type of software, including combinations thereof. Controller node 312 can receive instructions and other input at a user interface.
Inspection node 314 is a network element which can comprise a processor and associated circuitry to execute or direct the execution of computer-readable instructions. Inspection node 314 can retrieve and execute software from storage, which can include a disk drive, flash drive, memory circuitry, or some other memory device, and which can be local or remotely accessible. The software comprises computer programs, firmware, or some other form of machine-readable instructions, and may include an operating system, utilities, drivers, network interfaces, applications, or some other type of software, including combinations thereof. Inspection node 314 can, among other things, perform deep packet inspection of packets sent from and/or to wireless device 302. Deep packet inspection generally involves an inspection of packets beyond Open Systems Interconnection (OSI) layer 2 including an inspection of the data portion (also referred to as the payload portion) of a packet (and possibly also the header of a packet). That is deep packet inspection can involve an examination of any of layers 2 through 7 of the OSI model. The data portion of a packet remains distinct from a header portion, even where the packet receives additional header information (such as by packet encapsulation or a similar process). In other words, when a packet is encapsulated, any additional header information does not combine information from the data portion with any header portion. Inspection node 314 can be for example, a standalone computing device or network element, or the functionality of mode inspection node 314 can be included in another network element, such as a mobility management entity (MME), a gateway node, a proxy node, or another network element.
Communication network 316 can be a wired and/or wireless communication network, and can comprise processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Communication network 316 can be capable of carrying voice information and other data, for example, to support communications by a wireless device such as wireless device 302. Wireless network protocols may comprise code division multiple access (CDMA) 1xRTT, Global System for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Evolution Data Optimized (EV-DO), EV-DO rev. A, Worldwide Interoperability for Microwave Access (WiMAX), and Third Generation Partnership Project Long Term Evolution (3GPP LTE). Wired network protocols that may be utilized by communication network 108 comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Communication network 108 may also comprise a wireless network, including base stations, wireless communication nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof.
Communication links 318, 320, 322, 324, 326, 328, 330, 332, 334, 336, 338, 340 and 342 can be wired or wireless communication links. Wired communication links can comprise, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless communication links can comprise a radio frequency, microwave, infrared, or other similar signal, and can use a suitable communication protocol, for example, Global System for Mobile telecommunications (GSM), Code Division Multiple Access (CDMA), Worldwide Interoperability for Microwave Access (WiMAX), or Long Term Evolution (LTE), or combinations thereof. Other wireless protocols can also be used.
Other network elements may be present in communication system 300 to facilitate wireless communication but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between access nodes 304 and 306, gateway nodes 308 and 310, controller node 312, inspection node 314, and communication network 316 which are omitted for clarity, including additional processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements.
For example, an application requirement of an application running on wireless device 302 and a traffic class indicator associated with wireless device 302 can be determined. The application requirement can comprise, for example, a minimum data rate, a minimum throughput, a maximum permitted data error rate, a maximum permitted packet loss rate, and the like, required by the application to provide a minimum level of performance. The traffic class indicator can comprise a threshold level of priority associated with bearer data being sent from a wireless device, such as a quality of service class indicator (QCI) or similar traffic class indicator. The application requirement and/or the traffic class indicator can be determined by access node 304, or by inspection node 314 which can perform deep packet inspection of data traffic from wireless device 302, or by another network element of communication system 300.
The wireless communication link load can comprise a level of wireless resource utilization, such as a utilization of physical resource blocks or other units of resource allocation, a level of demand for communication link resources, a level of requested wireless communication link resources (such as by a buffer status report or other request for communication link resources), a number of wireless devices in active communication with the first access node, and the like. The backhaul load of access node 304 can comprise a level of resource utilization of communication link 328, such as an amount of bandwidth used for bearer and/or control data.
In operation 404, the probability of performing a first handover of the wireless device to a second access node and a second handover of the wireless device from the second access node to the first access node within a predetermined period of time is determined. Performing handovers of a wireless device between two access nodes within a relatively short period of time can be triggered, for example, when signal levels received by wireless device 302 from access nodes 304 and 306 vary over time, which can be caused by wireless device mobility, radio frequency interference, physical interference with the signal levels (such as by a physical obstruction, topographical feature, etc.) and the like. Signal levels can be monitored, and based on signal variation over time a probability of performing repeated handovers between access nodes can be determined. Access node mobility, such as direction of mobility, speed of mobility, and so forth, can also be used to determine the probability.
Additionally, or alternatively, the first access node can have a higher priority or handover preference than the second access node, which priority can also be used to determine the probability of ping ponging. For example, the first access node can use a first radio access technology which is given a higher priority than a second radio access technology used by the second access node. An example of such a case can be where the first radio access technology comprises LTE, WiMAX, or another 4G radio access technology, and the second radio access technology comprises CDMA or another 3G radio access technology, wherein the communication system places a priority on 4G radio access technology over 3G radio access technology. The priority can be imposed on an access node-level basis, or in a designated region, group of access nodes, tracking area, and the like.
Additionally, or alternatively, a number of re-connection requests during a period of time can be monitored, and the number can be used to determine the probability. For example, a number of re-connection requests received by access node 304 can be monitored, such as re-connection requests made by wireless device which are handed over to a second access node (such as access node 306). Such a historical number of re-connection requests can be used, alone or together with other information, in the determination of the probability.
Based on the application requirement, the traffic class indicator, the wireless communication link load, and the determined probability, a context maintenance time is calculated (operation 406). In an embodiment, a number of signaling communication sessions related to the wireless device is also determined and used in the determination of the context maintenance time. For example, when wireless device 302 is in active communication with access node 304, in order to control and support the communication session, signaling communication sessions can be established between access node 304 and controller node 312, and between access node 304 and gateway node 308. A signaling communication session can comprise a logical communication session established between network elements related to a communication session of a wireless device. One example of a signaling communication session is an S1 communication link. In an embodiment, a maximum time limit can be imposed on the context maintenance time. For example, a maximum signaling communication session time can be determined, and the context maintenance time can be required to be no greater than the maximum signaling communication session time. When the maximum signaling communication session time is reached, the signaling communication sessions can be release, to free up network communication resources among network elements.
When factors change over time, the context maintenance time is re-calculated (operation 408). For example, the application requirement can change when the wireless device uses a different application, or when the application activity changes so as change its requirements. Thus, when the application requirement of the application running on the wireless device meets a first criteria the context maintenance time is increased, and when the application requirement meets a second criteria the context maintenance time is decreased. The first criteria can comprise an application with a relatively high minimum data rate requirement, a relatively low permitted data loss rate, a relatively low maximum permitted data error rate, and the like, such as a voice over Internet Protocol (VoIP) application, a streaming video application, a streaming audio application, and the like. The second criteria can comprise an application with a relatively low minimum data rate requirement, a relatively high permitted data loss rate, a relatively high maximum permitted data error rate, and the like, such as a web browsing application, an email application, a messaging application, and the like.
As another example, the traffic class indicator can change when the wireless device uses a different application, or when the application sends and receives different data. Thus, when the traffic class indicator meets a third criteria the context maintenance time is increased, and when the traffic class indicator meets a fourth criteria the context maintenance time is decreased. The third criteria can comprise a traffic class indicator associated with a relatively high routing priority, such as a guaranteed bit rate (GBR) priority and the like. The fourth criteria can comprise a traffic class indicator associated with a relatively low routing priority, such as a non-guaranteed bit rate (NGBR) and the like.
Similarly, the loading of wireless communication link (e.g., of communication link 318) can change as resource demands change over time. In an embodiment, when the wireless communication link load meets a fifth criteria the context maintenance time is increased, and when the wireless communication link load meets a sixth criteria the context maintenance time is decreased. The fifth criteria can comprise a wireless communication link load which is greater than or equal to a threshold level of wireless communication link loading. The sixth criteria can comprise a wireless communication link load which is less than the threshold level of wireless communication link loading. The backhaul load of access node 304 (e.g., of communication link 328) can also change over time, and can also be taken into consideration in determining (and re-determining) the context maintenance time.
Moreover, the probability of the wireless device experiencing repeated handovers between access nodes can also change over time. In an embodiment, when the probability of performing the first handover and the second handover within a predetermined period of time meets a seventh criteria the context maintenance time is increased, and when the probability of performing the first handover and the second handover within the predetermined period of time meets an eighth criteria meets an eighth criteria the context maintenance time is decreased. The seventh criteria can comprise a threshold probability which can be met when the probability of performing the first handover and the second handover within a predetermined period of time is greater than or equal to the threshold probability. The eighth criteria can be met when the probability of performing the first handover and the second handover within a predetermined period of time is less than the threshold probability. Thus, the context maintenance time can be re-calculated and updated when one or more conditions change.
When the first handover is performed, a timer is started using the context maintenance time (operation 410). The timer can be started at access node 304, or at gateway node 308, or at controller node 312, or at another element of communication system 300. Communication session information and the signaling communication sessions related to the communication between the wireless device and the first access node are maintained until the timer expires (operation 412). By maintaining the communication session information until the timer expires, a delay in communication with wireless device 302 can be reduced when the wireless device is handed over between access nodes 304 and 306, and subsequently handed over back to access node 304. The communication session information can be maintained by sending a message instructing that the communication session information is not to be deleted or released until the timer has expired. The communication session information can also be maintained by delaying (or blocking) the sending of an instruction to delete the communication session information. Other methods of maintaining the communication session information are possible, including combinations thereof. Similarly, the signaling communication sessions can be maintained by sending an instruction to maintain them until the timer expires, by blocking or delaying an instruction to release the signaling communication sessions, and the like, including combinations thereof.
When the second handover is performed, communication is re-established with the wireless device using the communication session information and the signaling communication sessions (operation 414). For example, when wireless device 302 is handed over from access node 306 to access node 304, and the context maintenance timer has not expired, the communication session information related to the communication session between wireless device 302 and access node 304 can be used to re-establish the communication session. Further, when the context maintenance timer has not expired, the signaling communication sessions have not been released, and so the signaling communication sessions (e.g., between access node 304 and controller node 312, and between access node 304 and gateway node 308) can also be used in the re-establishment of the communication session with wireless device 302. Maintaining the communication session information and the signaling communication sessions can reduce delay in re-establishing communication with wireless device 302.
Examples of processing node 500 include access nodes 104, 106, 304 and 306, gateway nodes 308 and 310, controller node 312, and inspection node 314. Processing node 500 can also be an adjunct or component of a network element, such as an element of the aforementioned network elements. Processing node 500 can also be another network element in a communication system. Further, the functionality of processing node 500 can be distributed among two or more network elements of a communication system.
The exemplary systems and methods described herein can be performed under the control of a processing system executing computer-readable codes embodied on a computer-readable recording medium or communication signals transmitted through a transitory medium. The computer-readable recording medium is any data storage device that can store data readable by a processing system, and includes both volatile and nonvolatile media, removable and non-removable media, and contemplates media readable by a database, a computer, and various other network devices.
Examples of the computer-readable recording medium include, but are not limited to, read-only memory (ROM), random-access memory (RAM), erasable electrically programmable ROM (EEPROM), flash memory or other memory technology, holographic media or other optical disc storage, magnetic storage including magnetic tape and magnetic disk, and solid state storage devices. The computer-readable recording medium can also be distributed over network-coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion. The communication signals transmitted through a transitory medium may include, for example, modulated signals transmitted through wired or wireless transmission paths.
The above description and associated figures teach the best mode of the invention. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Those skilled in the art will appreciate that the features described above can be combined in various ways to form multiple variations of the invention, and that various modifications may be made to the configuration and methodology of the exemplary embodiments disclosed herein without departing from the scope of the present teachings. Those skilled in the art also will appreciate that various features disclosed with respect to one exemplary embodiment herein may be used in combination with other exemplary embodiments with appropriate modifications, even if such combinations are not explicitly disclosed herein. As a result, the invention is not limited to the specific embodiments described above, but only by the following claims and their equivalents.
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