Patent Application
20140378148
The present invention generally relates to the field of wireless communication systems and to systems and methods for self-organizing network optimization and load balancing.
Growth in wireless communication continues to increase. Demand for data services with high data bandwidth requirements has led to the introduction of multiple modulation techniques for wireless communication, such as Long Term Evolution (LTE), High-Speed Downlink Packet Access+ (HSDPA+), and CDMA2000 1xEV-DO (Evolution-Data Optimized or “EVDO”). Additionally, deployment of small cells including picocells and femtocells has become increasingly desirable for providing coverage. Small cells may be deployed, for example, in areas having high user density, such as airports or event venues. A small cell deployment typically has a 100 meter to 1 kilometer radius. Both voice and data modes are desired in small cell deployments. Development of multi-modal multi-modulation capable small cells is complex. Control of small cells in large networks, for example, for self-organizing networks, is also challenging.
A base station, in an embodiment, operates in a wireless communication network to provide communications coverage for user equipment. The base station autonomously maintains a neighbor list of information about other base stations. The neighbor list is created and updated using information from measurement reports from user equipment, measurement reports from receivers local to the base station, and reports from remote base stations. The base station uses the neighbor list in managing certain operations in a communication network, for example, to determine potential targets for handover of user equipment. The neighbor list can also be used for self-organizing network (SON) operations, such as radio parameter and resource management, and load balancing.
In one aspect, the invention provides a method for use in operating a first base station using a neighbor list that includes information about base stations near the first base station, the method comprising: receiving an attachment request from a user equipment; receiving a measurement report from the user equipment, the measurement report including information about transmissions detected by the user equipment, the transmissions being from one or more other base stations; requesting a network address associated with a second base station from a mobility management entity, the second base station being one of the base stations for which information is included in the measurement report; receiving the network address from the mobility management entity; requesting a connection to the second base station using the network address; receiving a connection response from the second base station; and adding the second base station to the neighbor list.
In one aspect, the invention provides a method for use in operating a first base station using a neighbor list that includes information about base stations near the first base station, the method comprising: configuring a radio receiver of the first base station to measure received signals; detecting, using the radio receiver, a transmission broadcast by a second base station; analyzing the detected transmission to create a measurement report; determining, using the measurement report, that the second base station should be added to the neighbor list; requesting a network address associated with the second base station from a mobility management entity; receiving the network address from the mobility management entity; requesting a connection to the second base station using the network address; receiving a connection response from the second base station; and adding the second base station to the neighbor list.
In one aspect, the invention provides a method for use in operating a first base station using a neighbor list that includes information about base stations near the first base station, the method comprising: receiving an attachment request from a user equipment, the attachment request including information about a second base station to which the user equipment is attached; requesting a network address associated with the second base station from a mobility management entity; receiving the network address from the mobility management entity; requesting a connection to the second base station using the network address; receiving a connection response from the second base station; and adding the second base station to the neighbor list.
In one aspect, the invention provides a method for use in operating a first base station, the method comprising: maintaining a neighbor list, the neighbor list including information about base stations near the first base station; and controlling one or more operations of the first base station using the neighbor list.
In another aspect, the invention provides a base station, comprising: one or more radio transceivers, each of the radio transceivers operable to establish wireless communications with user equipments; and a processor arranged for maintaining a neighbor list, the neighbor list including information about base stations near the base station; and controlling one or more operations of the base station using the neighbor list.
Other features and advantages of the present invention should be apparent from the following description which illustrates, by way of example, aspects of the invention.
The details of the present invention, both as to its structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:
The wireless communications network includes an evolved Node B (eNodeB or eNB) 110. A node B may also be referred to as a station or base station. The eNodeB 110 may be a small base station that can be deployed to provide coverage for a smaller area than a traditional, or macro, base station. A small base station may also be termed a picocell, femtocell, or small form factor cell. The eNodeB 110 can transmit and receive communications with user equipment. The eNodeB 110 can also communicate with a core network via a backhaul interface.
The eNodeB 110 includes a radio transceiver module 115, a radio receiver module 117, and a common radio element application manager (CREAM) module 112. The radio transceiver module 115 can transmit and receive RF signals to and from user equipment. The radio receiver module 117 is capable of detecting transmissions from transmitters, for example, from other eNodeBs. For example, the radio receiver module 117 may receive broadcast control messages. The radio receiver module 117 may also decode broadcast System Information Blocks in received transmissions. The radio receiver module 117 may be a transceiver that is operating without transmitting.
The CREAM module 112 contains processing capability for use by the eNodeB 110. The CREAM module 112 may perform the various processes described herein. For example, the CREAM module 112 may perform radio resource management, self-configuration, self-optimization, and mobility management of user equipment across multiple radio access technologies. The CREAM module 112 maintains a neighbor list of other stations. The neighbor list can include information about stations, such as the remote transceiver 160, whose transmissions can be detected by the eNodeB 110. The neighbor list may also contain information about more remote stations. Information in the neighbor list may include, for example, capabilities and statuses of the stations. The neighbor list may be stored, for example, in a database.
Local communication paths couple the CREAM module 112 and the radio transceiver module 115 and the radio receiver module 117. Uses of the communication path between the CREAM module 112 and the radio transceiver module 115 include the CREAM module 112 sending commands to user equipment and receiving reports and responses from the user equipment. Uses of the communication path between the CREAM module 112 and the radio receiver module 117 include control of operations of the radio receiver module 117 and transfer of reports of transmissions detected by the radio receiver module 117.
The CREAM module 112, in an embodiment, includes a processor module and a storage module. The processor module can provide the processing capability for the CREAM module 112. The storage module stores data for use by the processor module. The storage module may also store computer readable instructions for execution by the processor module. In addition to executing instructions, the processor module may include specific purpose hardware to accomplish some functions. The instructions can be used by the CREAM module 112 for accomplishing various functions of the eNodeB 110. In an embodiment, the storage module or parts of the storage module may be considered a non-transitory machine readable medium. The hardware of the CREAM module 112 may also be used by other modules of the eNodeB 110.
Although the eNodeB 110 is illustrated in
The eNodeB 110 may be configured to provide coverage for one or more mobile phone carriers or network providers. The radio transceiver module 115 (and other radio modules) of the eNodeB 110 may be remotely configured by a network administrator or operator. The radio transceiver modules may be configured to operate using various frequencies (or bands) and communication protocols (or modulation techniques). The radio transceiver modules of the eNodeB 110 may be reconfigured dynamically.
The eNodeB 110 may be arranged to provide communications coverage for multiple cells. Operations and information described as being for a particular eNodeB may be for one of more cells served by that eNodeB.
The wireless communications network also includes a remote transceiver 160. The remote transceiver 160 may be, for example, another eNodeB. The CREAM module 112 can communicate with the remote transceiver 160 via a communications network. Communications between the CREAM module 112 and the remote transceiver 160 may use, for example, an X2 interface. Uses of communications between the eNodeB 110 and the remote transceiver 160 include communication of reports and event notifications regarding status of the remote transceiver 160 and any user equipment connected to the remote transceiver 160. The remote transceiver 160 may perform the same or similar processes as the eNodeB 110. The meaning of local and remote in the disclosed processes can change according to where the processes are implemented.
The wireless communications network also includes a user equipment 150. The user equipment 150 may be, for example, a mobile phone, a tablet computer, or other device that uses voice, data, or other communications services. The user equipment 150 can receive and transmit signals to the eNodeB 110, the remove transceiver 160, or other stations of in communication network. The user equipment 150 can communicate with the radio transceiver 115 of the eNodeB 110 using a wireless communication path. The user equipment 150 can also communicate with the remote transceiver 160 using a wireless communication path. In addition to communicating user data between the user equipment 150 and other devices in or coupled to the wireless communication network, uses of the communication paths between the user equipment 150 and the eNodeB 110 and the remote transceiver 160 include sending control messages to the user equipment 150 and receiving reports and requests from the user equipment 150.
The wireless communications network also includes a mobility management entity (MME) 120. The MME 120 includes a database of network addresses of the LTE transceivers within the wireless communications network. With reference to the eNodeB 110, the database of network addresses may be referred to as a remote database. The MME 120 can operate as a control node that processes signaling between the user equipment and the wireless network. Functions supported by the MME 120 can include bearer management functions (e.g., establishment, maintenance, and release of bearers) and connection management functions (e.g., establishment of connection and security between user equipment and the wireless network).
Although the wireless communications network of
Example embodiments of an eNodeB are described in U.S. application Ser. No. 13/444,704, filed Apr. 11, 2012 and published as U.S. 2010/0264470, which is hereby incorporated by reference. For example, the picocell described with reference to FIG. 2 in U.S. application Ser. No. 13/444,704 may be used to implement the eNodeB 110. Similarly, the wireless communications network may be implemented in the wireless communications network described with reference to FIG. 1 in U.S. application Ser. No. 13/444,704.
The processes of
A neighbor list is maintained by a base station, for example, the eNodeB 110 of
The user equipment 150 may request attachment 215 to the eNodeB 110. In the illustrated process, the eNodeB 110 accepts attachment 220 by the user equipment 150. The CREAM module 112 in the eNodeB 110 can receive the attachment request and accept the attachment.
After attaching the user equipment 150, the CREAM module 112 of the eNodeB 110 commands 230 the user equipment 150 to supply measurement reports. The measurement reports include information about signal received from other eNodeBs (e.g., the remote transceiver 160). The measurement reports include identification of the eNodeBs and an indication of signal strength or quality. The command 230 from the eNodeB 110 may be for information about transmissions detected with greater than a minimum signal strength. The minimum signal strength may be specified in the command or may be predetermined.
To supply the measurement reports, the user equipment 150 detects transmissions broadcast 245 from the other eNodeBs, such as the remote transceiver 160. The user equipment 150 analyzes to the received transmissions to determine information for the measurement reports. For example, the user equipment 150 may measure reference signal received power. The user equipment 150 supplies the measurement reports 255 to the CREAM module 112 in the eNodeB 110.
The eNodeB 110 sends requests 265 to the MME 120 for the network address of the remote transceiver 160 (and other eNodeBs for which measurement reports were received). The network addresses may be, for example, the IP address of the eNodeBs. The MME 120 responds 270 by supplying the requested network addresses to the eNodeB 110.
Using the network addresses, the CREAM module 112 in the eNodeB 110 requests a connection 280 with the remote transceiver 160 (and other eNodeBs for which measurement reports and network addresses were received). The remote transceiver 160 (and other eNodeBs) accepts the connection request 285. The CREAM module 112 in the eNodeB 110 then adds 288 the remote transceiver 160 (and other eNodeBs) to its neighbor list. The added eNodeBs may then be considered for use, for example, in subsequent handovers of user equipments.
The CREAM module 112, based on the measurement reports, can determine whether another eNodeB is a suitable candidate to be used as a neighbor. The determination can be based, for example, on signal strength. For eNodeBs that are neighbor candidates, the eNodeB 110 sends requests 365 to the MME 120 for the network address of the remote transceiver 160 (and other eNodeBs). The MME 120 responds by supplying the requested network addresses 370 to the eNodeB 110. The CREAM module 112 in the eNodeB 110 requests a connection 380 with the remote transceiver 160 (and other eNodeBs). The remote transceiver 160 (and other eNodeBs) accepts the connection request 385. The CREAM module 112 in the eNodeB 110 then adds the remote transceiver 160 (and other eNodeBs) to its neighbor list 388. The added eNodeBs may then be considered for use. In various embodiments, the process steps for acquiring addresses, establishing connections, and adding to the neighbor list are the same or similar to those in the process of
The CREAM module 112 can determine whether the remote transceiver 160 is a suitable candidate to be used as a neighbor. The determination can be based, for example, on shared abilities or shared coverage. If the remote transceiver 160 is neighbor candidate, the eNodeB 110 sends a request 465 to the MME 120 for the network address of the remote transceiver 160. The MME 120 responds by supplying the requested network addresses 470 to the eNodeB 110. The CREAM module 112 in the eNodeB 110 requests a connection 480 with the remote transceiver 160. The remote transceiver 160 accepts the connection request 485. The CREAM module 112 in the eNodeB 110 then adds the remote transceiver 160 to its neighbor list 488. The added remote transceiver may then be considered for use. In various embodiments, the process steps for acquiring addresses, establishing connections, and adding to the neighbor list are the same or similar to those in the processes of
The CREAM module 112 of the eNodeB may receive notification of handover failure. The notification may be detected, for example, by the radio transceiver module 115 of the eNodeB 110 or by the remote transceiver 160. When radio transceiver module 115 detects handover failure, the radio transceiver module 115 signals the failure 525 to the CREAM module 112. Similarly, when the remote transceiver 160 detects handover failure, the remote transceiver 160 signals the failure 525′ to the CREAM module 112.
The CREAM module 112 maintains statistical information about handover failures. The statistics are for particular handover targets. When the CREAM module 112 receives 525, 525′ the indication of handover failure, it updates 538 the statistical information. Example handover failure statistics include a count of failures, a ratio of handover failures to handover attempts, and an average time between handover failures.
The CREAM module 112 can analyze the statistical information to detect that handovers to the remote transceiver 160 have a high failure rate. The detection of a high failure rate may vary with the statistics used. For example, CREAM module 112 may detect a high failure rate when more than half of the attempted handovers fail. The detection may also be dynamic, for example, based on other available neighbors. When CREAM module 112 detects a high failure rate, the remote transceiver 160 is removed from the neighbor list 558. The CREAM module 112 then disconnects communication 560 with the remote transceiver 160.
The process can also be used to add neighbors of neighbors to a neighbor list. For example, after a new neighbor cell is added to a neighbor list using one of the processes of
The process may begin when the CREAM module 112 of the eNodeB 110 receives a report 715 from the remote transceiver 160 about neighbors of the remote transceiver 160. The report includes information about eNodeBs that are in the neighbor list of the remote transceiver 160. The remote transceiver 160 may send the neighbor report, for example, after a communication connection (e.g., as in steps 280, 285 of the process of
The CREAM module 112 of the eNodeB 110 analyzes the received neighbor report to detect whether it includes information about stations that are not in the neighbor list. Any new stations that are not in the neighbor list are added to the neighbor list 718.
After new stations are added to the neighbor list, the CREAM module 112 of the eNodeB 110 analyzes the updated neighbor list to check for radio parameter conflicts 728. If a conflict is detected, the CREAM module 112 can recon
The CREAM module 112 filters 818 the received resource usage information. The filtering may time average the information. The CREAM module 112 uses the filtered resource usage information to determine one or more load balancing actions 820. In an embodiment, conditions for handover of user equipment are modified. For example, if the resource usage information indicates that a particular cell has low utilization, the conditions for handover can be modified to increase handovers to that particular cell.
The CREAM module 112 filters and analyzes 918 the received resource usage information. The CREAM module 112 uses the resource usage information to determine one or more load balancing actions 920. One load balancing action that may be taken includes the CREAM module 112 sending a handover command 920a to the user equipment 150 that is attached to the eNodeB to handover to a different cell. This type of load balancing action may be taken, for example, when the analysis of the resource usage indicates that the resources are highly used at the eNodeB 110.
Another load balancing action that may be taken includes the CREAM module 112 activating 920b a standby radio transceiver 115′. The standby radio transceiver 115′ is a radio transceiver in the eNodeB 110 that was not being used for communication with user equipment. Activating the standby radio transceiver 115′ transitions it to a state for use in communications with user equipment. Another load balancing action that may be taken includes the CREAM module 112 deactivating 920c the previously activated standby radio transceiver 115′. Activating a standby radio receiver for load balancing may be performed, for example, when the analysis of the resource usage indicates that the resources are highly used at the eNodeB 110. Conversely, deactivating a standby radio receiver for load balancing may be performed, for example, when the analysis of the resource usage indicates that the resources are lightly used at the eNodeB 110.
Another load balancing action that may be taken includes the CREAM module 112 signaling 920d the radio transceiver 115 that attachments of new user equipment to the radio transceiver 115 may be disallowed. Another load balancing action that may be taken includes the CREAM module 112 signaling 920e the radio transceiver 115 that attachments of new user equipments to the radio transceiver 115 can now be allowed. The various load balancing actions 920 can also be performed by the process of
Those of skill will appreciate that the various illustrative logical blocks, modules, units, and algorithm steps described in connection with the embodiments disclosed herein can often be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, units, blocks, modules, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular system, but such implementation decisions should not be interpreted as causing a departure from the scope of the invention. In addition, the grouping of functions within a unit, module, block, or step is for ease of description. Specific functions or steps can be moved from one unit, module, or block without departing from the invention.
The various illustrative logical blocks, units, steps and modules described in connection with the embodiments disclosed herein can be implemented or performed with a processor, such as a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm and the processes of a block or module described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or other form of machine or computer readable storage medium. An exemplary storage medium can be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can reside in an ASIC. Additionally, device, blocks, or modules that are described as coupled may be coupled via intermediary device, blocks, or modules. Similarly, a first device may be described a transmitting data to (or receiving from) a second device when there are intermediary devices that couple the first and second device and also when the first device is unaware of the ultimate destination of the data.
The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter that is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art.
