HK1179062B - Increasing time interval between successive searches for signaling of neighboring cells of a different wireless technology - Google Patents

Description

Increase the time interval between consecutive signaling searches for neighboring cells using different wireless technologies

Background Art

Various wireless access technologies have been proposed or implemented to enable mobile stations to communicate with other mobile stations or with wired terminals connected to a wired network. Examples of wireless access technologies include: GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications System) technologies defined by the Third Generation Partnership Project (3GPP); and CDMA 2000 (Code Division Multiple Access 2000) technology defined by 3GPP2. CDMA 2000 defines a type of packet-switched wireless access network known as HRPD (High Rate Packet Data) wireless access network.

Another newer standard for providing packet-switched radio access networks is the Long Term Evolution (LTE) standard, developed by 3GPP and designed to enhance UMTS technology. LTE is also known as EUTRA (Evolved Universal Terrestrial Radio Access). EUTRA is considered a fourth-generation (4G) technology, and wireless network operators are turning to it to offer enhanced services.

Summary of the Invention

In summary, according to some embodiments, a mobile station connected to an access network may receive control information identifying neighboring cells that utilize a different wireless technology than the access network. The mobile station searches for neighboring cells that utilize the different wireless technology, and in response to signaling indicating that the mobile station cannot detect a neighboring cell, the mobile station increases the time interval between successive searches for the neighboring cells.

Other or further features will be apparent from the following description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are described with reference to the following drawings:

FIG1 is a simplified diagram of an example configuration including different types of wireless access networks, including some embodiments;

FIG2 is an information flow diagram of a process according to some embodiments; and

FIG3 is a simplified diagram of a wireless station according to some embodiments.

DETAILED DESCRIPTION

Wireless network operators are transitioning to fourth-generation (4G) wireless networks. One type of 4G wireless network is the Long Term Evolution (LTE) wireless network defined by the Third Generation Partnership Project (3GPP). The LTE standard is also known as the EUTRA (Evolved Universal Terrestrial Radio Access) standard.

As part of this transition, the wireless network operator can deploy access networks of different technologies so that a mobile station can seamlessly operate with either access network using different technologies. For example, a mobile station can transition from an access network using a first technology to an access network using a second, different technology. Alternatively, a mobile station can perform cell selection when initially booting up from an access network using different technologies. In some instances, a wireless network operator can boot up an HRPD (High Speed Packet Data) access network and an EUTRA access network. HRPD is defined by the CDMA (Code Division Multiple Access) 2000 standard developed by 3GPP2.

In some implementations, the transition from HRPD to EUTRA involves the use of evolved HRPD (eHRPD) technology. An eHRPD access network can interoperate with an EUTRA radio access network. Mobile stations supporting eHRPD technology can switch between eHRPD and EUTRA access networks. Furthermore, mobile stations supporting eHRPD can perform cell reselection for either EUTRA or eHRPD access networks.

Therefore, a network may include both HRPD cells and EUTRA cells. In such a network, HRPD cells include the HRPD access network or eHRPD access network, and EUTRA cells include the EUTRA access network. Some HRPD cells may overlap with EUTRA cells. "Cell" may refer to an entire cell, a block of a cell, or any other portion of a cell.

A mobile station within an HRPD cell can be informed by neighboring EUTRA cells. Once a mobile station identifies the presence of an EUTRA cell, it can attempt to acquire signaling from the neighboring EUTRA cell. For example, the mobile station can attempt to search for pilot signaling from the EUTRA cell to determine whether it can transfer to one of the EUTRA cells. This transfer is a form of transition from an earlier generation (e.g., third generation or 3G) cell to a higher generation (e.g., fourth generation or 4G) cell. Pilot signaling includes signaling continuously sent from a base station within a particular cell to allow a mobile station to detect the presence of that base station. Measurements made on the pilot signal can enable the mobile station to determine whether a wireless connection can be established with the base station.

There is a possibility that an HRPD cell, which has informed a mobile station of the presence of one or more EUTRA cells, may not have complete EUTRA coverage or may not have any EUTRA coverage at all. Within an HRPD cell (which may be a subset of an HRPD cell or the entire HRPD cell), there may be areas without any EUTRA coverage. When a mobile station is within such an area, the mobile station attempts to search for pilot signals of neighboring EUTRA cells, even if the mobile station cannot find any neighboring EUTRA cells within such an area. The repeated searches for EUTRA pilot signals when the mobile station is within an area of HRPD cells without EUTRA coverage waste battery power in the mobile station.

According to some embodiments, techniques or methods are provided for conserving energy in a mobile station when the mobile station is located in an area of an HRPD cell without any EUTRA coverage. Such techniques or methods may be implemented by allowing the mobile station to increase the time interval between neighboring EUTRA cell pilot signaling searches in response to the mobile station being unable to detect any neighboring EUTRA cell pilot signals, even if the mobile station has received a control message regarding the existence of a neighboring EUTRA cell within the HRPD cell.

Although only HRPD and EUTRA technologies are described herein, it should be noted that alternative embodiments may utilize other wireless protocols. More generally, when a mobile station is connected to a first access network utilizing a first wireless technology, the mobile station may receive control information indicating a neighboring cell utilizing a different wireless technology. The mobile station searches for signaling indicating the neighboring cell utilizing the different wireless technology. In response to the signaling indicating that the mobile station cannot detect a neighboring cell, the mobile station increases the time interval between successive searches for the signaling to conserve battery power in the mobile station.

The following discussion is directed to HRPD and EUTRA techniques - it should be noted that similar techniques discussed below can be applied to other types of wireless protocols.

1 illustrates an example configuration including different types of access networks, including EUTRA access network 102, HRPD access network 104, and eHRPD access network 106. EUTRA access network 102 is part of a EUTRA cell, while HRPD access network 104 and eHRPD access network 106 are part of their respective HRPD cells.

Although FIG1 shows only one EUTRA access network 102, one HRPD access network 104, and one eHRPD access network 106, it should be noted that there are typically multiple EUTRA access networks, multiple HRPD access networks, and multiple eHRPD access networks. As used herein, the term "access network" or "radio access network" refers to a device that enables a mobile station to wirelessly connect to the access network to obtain services provided by the target network (packet data network 116).

Based on EUTRA technology, the EUTRA access network 102 includes an enhanced Node B (eNode B), which is a type of base station. The HRPD access network 104 includes an HRPD base station, and the eHRPD access network 106 includes an eHRPD base station. A base station can perform one or more of the following tasks: radio resource management, mobility management functions for managing the mobility of mobile stations, routing of traffic, etc. Generally speaking, the term "base station" can refer to a cellular network base station, or an access point for any type of wireless network, or any type of wireless transmitter/receiver that communicates with a mobile station. The term "base station" can also include related controllers, such as a base station controller or a wireless communication network controller. It is expected that the term "base station" can also refer to a femto base station or access point, a micro base station or access point, or a pico base station or access point. A "base station" can refer to a mobile phone, a laptop, a personal digital assistant (PDA), or an embedded device such as a health monitor or an attack alarm, etc.

As shown in Figure 1, in EUTRA network 100, a mobile station 108 is wirelessly connected to EUTRA access network 102. EUTRA access network 102 is in turn connected to various other components, including a serving gateway 110 and a mobility management entity (MME) 112. MME 112 is a control node in EUTRA access network 102. For example, MME 112 is responsible for tracking and paging procedures for idle mobile stations. MME 112 is also responsible for selecting a serving gateway for mobile stations in the initial connection state and during handover. MME 112 is also responsible for authenticating mobile station users.

Serving gateway 110 selects a path for carrying data packets. Serving gateway 110 also acts as a mobility locator for the user interface when switching between different access networks. Serving gateway 110 is then connected to packet data network (PDN) gateway 114, which is used to connect mobile station 108 to packet data network 116 (e.g., the Internet, a network providing various services, etc.).

In HRPD network 101, mobile station 118 is wirelessly connected to HRPD access network 104. HRPD access network 104 is in turn connected to packet data serving node (PDSN) 120, which is in turn connected to packet data network 116.

Furthermore, to enable intercommunication between HRPD network 101 and EUTRA network 100, an eHRPD access network 106 is provided that is wirelessly connected to mobile station 122. eHRPD access network 106 is in turn connected to HRPD serving gateway (HSGW) 124. HSGW 124 is an entity that terminates the eHRPD access network interface from eHRPD access network 106. HSGW 124 selects a path for packet data traffic originating from or terminating at a mobile station. HSGW 124 enables intercommunication between the mobile station and EUTRA network 100. This intercommunication functionality includes support for mobility, policy control and charging, access authentication, roaming, and other functions. HSGW 124 supports seamless interworking and technical mobility transfer between EUTRA network 100 and eHRPD access network 106.

The introduction of the EUTRA, HRPD, and eHRPD standards is intended to reference current standards and those that evolve over time. It is anticipated that future standards derived from the EUTRA, HRPD, or eHRPD standards will be introduced under different names. It is anticipated that the introduction of "EUTRA," "HRPD," and "eHRPD" is also intended to cover these subsequently evolved standards. Furthermore, as noted above, techniques or methods according to some embodiments are also applicable to systems using other types of wireless protocols.

FIG2 is a flow diagram of a process according to some embodiments. The HRPD access network (104 or 106) of an HRPD cell sends (at 202) overhead information that is broadcast within the HRPD cell and received by a mobile station within the HRPD cell. In some examples, the overhead information is referred to as OtherRATNeighbor information. The OtherRATNeighbor information identifies other RAT (Radio Access Technology) neighboring cells adjacent to the HRPD cell, where the other RAT neighboring cells are EUTRA cells. The OtherRATNeighbor information may be sent periodically or intermittently. At each specified time interval, the mobile station may be awakened (if the mobile station is in a low energy mode) to receive the OtherRATNeighbor information.

In other implementations, in addition to the OtherRATNeighbor information, other types of control information may be used. Such other control information may be broadcast information or unicast information targeted at a specific mobile station.

The OtherRATNeighbor information may also include an attribute specifying a maximum time interval between consecutive searches for pilot signaling to be performed by the mobile station. In an optional implementation, the attribute specifying the maximum time interval between consecutive searches for pilot signaling may also be included in different control information sent from the access network to the mobile station.

In some implementations, the OtherRATNeighbor message (or other control information) may include an option field set to a pre-set value to instruct the mobile station not to increase the time interval between searches when it cannot detect pilot signaling from other RAT cells. This option field, if set to a different value, may allow the mobile station to increase the time interval between searches when it cannot detect pilot signaling from other RAT cells. In some instances, the option field may be part of an attribute that indicates the maximum time interval between searches. Alternatively, this option field may be part of another attribute.

In response to the OtherRATNeighbor message, the mobile station searches (at 204) for pilot signaling of the other RAT neighboring cell identified by the OtherRATNeighbor message. Next, the mobile station determines (at 206) whether pilot signaling of the identified RAT neighboring cell is detected. If pilot signaling is not detected, the time interval between successive searches for pilot signaling of the other RAT neighboring cell is increased (at 208), and the process returns to 204 to repeat the search for pilot signaling of the other RAT neighboring cell at the increased time interval. The increment of the time interval can be specified using an attribute of the OtherRATNeighbor message indicating the amount of time to increase. It should be noted that the increase in the time interval between successive searches for pilot signaling performed at 208 cannot exceed the maximum time interval between searches specified in the attributes of the OtherRATNeighbor message (or other control information).

If at 206 the mobile station determines that pilot signaling of an other RAT neighbor cell has been detected, the mobile station may reduce (at 210) the time interval between consecutive searches for pilot signaling, if appropriate. For example, if the time interval between consecutive searches for pilot signaling was previously increased, the time interval may be reduced. Next, control returns to task 204, where a search for pilot signals of other RAT neighbor cells is performed using the updated time interval between searches.

As mentioned above, the access network can also instruct the mobile station not to increase the interval between pilot signaling searches when it cannot find pilot signaling from other RAT neighboring cells. For example, the OtherRATNeighbor information may include an option field set to a preset value to instruct the mobile station not to increase the interval between searches when it cannot detect pilot signaling from other RAT neighboring cells. This ability to selectively control whether the mobile station increases the interval between searches provides greater flexibility in access network control.

FIG3 is a simplified diagram of a wireless station 300. The wireless station can be a mobile station (e.g., mobile stations 108, 118, or 122 in FIG1 ) or a base station (e.g., an eNodeB, HRPD base station, or eHRPD base station in FIG1 ). The wireless station 300 includes a processor (or multiple processors) 302 coupled to a storage medium 304. Machine-readable instructions 306 are executed on the processor 302 to perform various tasks associated with the wireless station 300, such as those described in FIG2 or 3 . The wireless station 300 also includes an interface 308 for communicating via a wireless link, such as a radio frequency (RF) link.

Machine-readable instructions 306 are loaded for execution on processor 302. The processor may include a microprocessor, a microcontroller, a processor module or subsystem, a programmable integrated circuit, a programmable gate array, or other control or computing device.

Data and instructions are stored in respective storage devices that are executed as one or more computer-readable or machine-readable storage media. Storage media include various forms of memory, including semiconductor memory devices such as dynamic or static random access memory (DRAM or SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory; disks such as hard disks, floppy disks, and removable hard disks; other magnetic media including magnetic tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices. It should be noted that the above instructions can be provided on a computer-readable or machine-readable storage medium, or they can be provided on multiple computer-readable or machine-readable storage media distributed in a large system, which may have multiple nodes. Such computer-readable or machine-readable storage media are considered part of an article (or product). Such an article or product can refer to any manufactured single component or multiple components.

In the aforementioned description, many details are provided to provide an understanding of the subject matter disclosed herein. However, some implementations may not require some or all of these details. Other implementations may include modifications and variations of the above details. It is intended that the appended claims include these modifications and variations.

Claims (20)

1. A wireless communication method, comprising: A mobile station connected to a first access network receives control information that identifies multiple neighboring cells using wireless technologies different from those of the first access network. The mobile station searches for signaling from multiple neighboring cells using different wireless technologies; and In response to the mobile station's inability to detect signaling from the identified multiple neighboring cells, the mobile station increments the time interval between consecutive signaling searches by a time amount due to the control information, wherein the control information includes a field indicating the time amount for increasing the time interval between consecutive signaling searches. The different wireless technologies used in the multiple adjacent cells are wireless technologies that are successors to the wireless technologies used in the first access network, and the different wireless technologies are LTE technologies. 2. The wireless communication method according to claim 1, wherein searching the signaling of the identified plurality of neighboring cells includes searching the pilot signaling of the identified plurality of neighboring cells. 3. The wireless communication method according to claim 1, further comprising: The mobile station receives an attribute indicating the maximum time interval between signaling searches that the mobile station can set, wherein an increase in the time interval cannot exceed the maximum time interval. 4. The wireless communication method according to claim 3, wherein receiving the attribute includes: receiving an attribute having a field that can be set to a first value to cause the mobile station to increase the time interval between consecutive signaling searches, and can also be set to a second value to cause the mobile station not to increase the time interval between consecutive signaling searches. 5. The wireless communication method according to claim 3, wherein receiving the attribute includes the attribute in the receiving control information. 6. The wireless communication method according to claim 1, wherein receiving the control information includes receiving overhead information broadcast by the first access network. 7. The wireless communication method according to claim 1, wherein multiple adjacent cells use Evolved Universal Terrestrial Radio Access (EUTRA) technology. 8. The wireless communication method according to claim 7, wherein the first access network is based on High-Speed Packet Data (HRPD) technology. 9. A mobile station, comprising: An interface for wireless communication with an access network using the first technology; and At least one processor is configured to: Receive control information indicating the presence of multiple neighboring cells using a second technology different from the first technology; Searching for signaling from multiple neighboring cells; and In response to the inability to detect signaling from multiple neighboring cells, the time interval between consecutive signaling searches of multiple neighboring cells is increased by a time amount due to the control information, wherein the control information includes a field indicating the time amount for increasing the time interval between consecutive signaling searches. The second technology of the plurality of adjacent cells is a technology that is a descendant of the first technology of the access network, and the second technology is LTE technology. 10. The mobile station according to claim 9 can be configured to use both the first technology and the second technology simultaneously. 11. The mobile station according to claim 9, wherein the signaling of the plurality of neighboring cells to be searched by the mobile station includes pilot signaling. 12. The mobile station of claim 9, wherein at least one processor is configured to: further receive an attribute indicating a maximum time interval between signaling searches that the mobile station can set, wherein an increase in the time interval between consecutive searches cannot exceed the maximum time interval. 13. The mobile station according to claim 9, wherein multiple adjacent cells use Evolved Universal Terrestrial Radio Access (EUTRA) technology. 14. The mobile station according to claim 9, wherein the access network is based on High-Speed Packet Data (HRPD) technology. 15. A wireless communication method, comprising: The system transmits control information identifying multiple neighboring cells using a wireless technology different from the wireless technology used by the base station. This control information is used to cause the mobile station to search for signaling from the identified neighboring cells, and to cause the mobile station to increase the time interval between consecutive signaling searches by a certain amount in response to the inability to detect signaling from the identified neighboring cells. The control information includes a field indicating the amount of time used to increase the time interval between consecutive signaling searches. The different wireless technologies used in the multiple adjacent cells are wireless technologies that are successors to the wireless technologies used by the base station, and the different wireless technologies are LTE technologies. 16. The wireless communication method according to claim 15, wherein the signaling includes pilot signaling. 17. The wireless communication method according to claim 15, wherein multiple adjacent cells use Evolved Universal Terrestrial Radio Access (EUTRA) technology. 18. The wireless communication method according to claim 15, wherein the access network is based on High-Speed Packet Data (HRPD) technology. 19. A base station, comprising: An interface for wireless communication with the mobile station; and At least one processor to: Control information is transmitted to identify multiple neighboring cells using a wireless technology different from the wireless technology used by the base station. This control information is used to cause the mobile station to search for signaling in the identified multiple neighboring cells, and to cause the mobile station to increase the time interval between consecutive signaling searches by a certain amount in response to the inability to detect signaling in the identified multiple neighboring cells. The control information includes a field indicating the amount of time used to increase the time interval between consecutive signaling searches. The different wireless technologies used in the multiple adjacent cells are wireless technologies that are successors to the wireless technologies used by the base station, and the different wireless technologies are LTE technologies. 20. The base station according to claim 19, wherein multiple adjacent cells use Evolved Universal Terrestrial Radio Access (EUTRA) technology, and the base station is based on High-Speed Packet Data (HRPD) technology.