The technology relates to radio communications, and in particular, to wireless networks that use movable/mobile radio access points, APs.
Increasing uptake of the mobile broadband services and end-user requirements to always being wirelessly “connected” have driven a new generation of base stations and access points. A majority of these base stations are relatively smaller in size, have a relatively lower output power, and cover a smaller area as compared to conventional cellular base stations, sometimes called macro base stations. Such smaller base stations can extend the coverage of cellular networks, enhance capacity in hotspots, increase effective cell throughput, and reduce average radio-transmission power at the User Equipment, UE, especially in highly shadowed areas, thereby leading to longer UE battery life. Because of these advantages, Long-Term Evolution, LTE-Advanced, corresponding to 3rd Generation Partnership Project (3GPP) Release 10 of the LTE standard, introduced support for Relay Nodes, RNs, which are an example of a smaller base station. Another example of a smaller base station includes Access Points, APs, such as specified in the Institute of Electrical and Electronics Engineers, IEEE, 802.11 family of standards.
A goal with smaller base stations is to support several wireless access technologies, e.g., Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), LTE, and Wireless Fidelity, WiFi, in one physical base station node and interwork with macro base stations to provide a continuous mobile broadband access network providing seamless mobility throughout the network to the end users. The small base stations may be deployed both indoors and outdoors and even inside moving vehicles such as in trains, buses, ships, taxis, trucks, and private cars. While many small base stations may be managed by a mobile operator, some of the access points may be private—and hence may be used only by selected subscribers. Alternatively, they may be completely open to anyone, e.g., as a courtesy service from a shop owner, town, or other.
These kinds of deployments that include macro and smaller base stations are generically referred to as Heterogeneous Networks, Hetnet. Typically, there will be overlapping coverage provided by a set of base stations at any one point, which means that a mobile radio station at any one position may connect to a multitude of base stations. Mobile radio stations are also referred to as User Equipments, UEs. In this type of situation, it is important to select an optimal base station for a UE to connect to at any one time. For example, one aspect of the base station selection process is that a UE should preferably not connect to a base station that in a short time will no longer be in radio range of the UE. One example of such a situation occurs if the UE is moving, e.g., the UE is located in a moving train. While moving, especially at higher speeds, the UE should ideally not connect to a small cell with a relatively short range because the UE will likely be outside its cell coverage in a short period of time.
A similar problem occurs when the base station itself is moving at high speed, e.g., the base station is located inside a train, a bus, or other vehicle. In this case, UEs not moving along with the base station should preferably not attach to the moving base station. A stationary UE that attaches to a moving base station may lead to two unnecessary handoffs in a very short period of time: one handoff into the cell of the moving base station and a second handoff out from that moving base station cell. This unwanted mobility signaling in the network can be quite significant if every UE around a moving bus connects and de-connects to an on-board base station as the bus moves through a busy downtown area.
Another drawback is the risk of poor end-user performance and dropped calls associated with a cell change. This risk, in the case of a moving base-station, is particularly large since the time from good radio connectivity to no radio satisfactory connectivity with the cell may be very short. This also increases the risk that a controlled handoff will not be performed before connectivity is lost.
Yet another problem is that an on-board base station is likely to be dimensioned for on-board traffic. If surrounding stationary UEs also attach to the on-board base station, then there is a high risk that the on-board base station and its backhaul network may become congested, resulting in poor performance both for the on-board UEs and the surrounding stationary UEs trying to connect to that base station. These problems become even more severe in areas with a large number of different on-board base stations such as a bus terminal, a train station, or generally a busy city environment with many taxis and buses passing by.
What is needed is technology for resolving these and other problems that may be caused by moving base stations in communication systems.
A user equipment, UE, includes radio circuitry that communicates with a radio node and processing circuitry that determines a mobility state of the radio node as one of a moving mobility state and a non-moving mobility state. The processing circuitry also determines control information relating to UE cell (re-)selection and/or handover behavior based on the determined mobility state of the radio node. Based on the determined control information, the processing circuitry controls UE cell (re-)selection and/or handover behavior in relation to the radio node.
In example embodiments, the UE radio circuitry may communicate with a Wi-Fi access point, AP. The UE processing circuitry detects the Wi-Fi AP and determines whether the Wi-Fi AP is moving based on a moving AP indication. A non-limiting example of a moving AP indication includes AP venue information. Based on the determination that the Wi-Fi AP is moving and other information and/or policies known by the UE, the processing circuitry is enabled to control the UE cell (re-)selection and/or handover behavior. In example implementations, the processing circuitry may determine that the Wi-Fi AP is moving based on a beacon frame or a probe response frame received from the Wi-Fi AP that includes the moving AP indication or an Access Network Query Protocol, ANQP, signaling that includes the moving AP indication.
In other example embodiments, the UE radio circuitry is also configured to communicate with a cellular base station, BS. In such embodiments, the UE processing circuitry generates a neighbor cell report that includes the cell served by the Wi-Fi AP as a neighbor cell in the report and the moving AP indication for the Wi-Fi AP, and the radio circuitry transmits the neighbor cell report to the cellular BS. In addition, the UE may receive from the cellular BS network-based cell (re-)selection or handover control information determined based on the moving AP indication. The UE decides whether to connect to the Wi-Fi AP based on the network-based cell (re-)selection or handover control information. In another example embodiment, the UE radio circuitry receives other information from the cellular BS based on the moving AP indication, and the processing circuitry is enabled to decide whether to connect to the Wi-Fi AP based on the received information and the determined mobility state of the Wi-Fi AP.
In yet another example embodiment, the UE is configured by a user to detect and process a moving AP indication. Thereafter, the UE processing circuitry receives from the user of the UE a user decision whether to perform a cell (re-)selection and/or handover to the Wi-Fi AP based on the moving AP indication. In this example, the other information may include the user's decision or policies configured by the user.
In yet another example embodiment, the UE is configured by a network operator to detect and process moving AP indications. Thereafter, the UE processing circuitry decides locally at the UE whether to perform a cell (re-)selection and/or handover to the Wi-Fi AP based on the moving AP indication. In one example implementation, the UE is configured by a network operator with policy information to detect and process moving AP indications. In this case, the other information includes the policy information.
Another aspect of the technology includes a method implemented in a UE comprising the following steps:
a—determining a mobility state of a radio node as one of a moving mobility state and a non-moving mobility state;
b—determining control information relating to UE cell (re-)selection and/or handover behavior based on the determined mobility state of the radio node; and
c—controlling UE cell (re-)selection and/or handover behavior in relation to the radio node based on the determined control information.
Another aspect of the technology includes a computer product embodied in a non-transitory, computer-readable storage medium containing instructions, which when executed by data processing circuitry, perform the above method and other methods described below.
Another aspect of the technology includes a radio base station in an example embodiment that establishes a connection with a UE. Thereafter, the base station receives a neighbor cell report from the UE including a moving AP indication and provides the UE with a cell (re-)selection and/or handover decision node based on the moving AP indication.
Still another aspect of the technology includes a Wi-Fi access point, AP, that communicates with one or more UEs. Processing circuitry in the AP transmits a signal to UEs within range including a moving AP indication as to whether the Wi-Fi AP is moving to permit a cell (re-)selection and/or handover decision for the UE with respect to the Wi-Fi AP based on the moving AP indication
The following description sets forth specific details, such as particular embodiments for purposes of explanation and not limitation. But it will be appreciated by one skilled in the art that other embodiments may be employed apart from these specific details. In some instances, detailed descriptions of well known methods, nodes, interfaces, circuits, and devices are omitted so as not to obscure the description with unnecessary detail. Those skilled in the art will appreciate that the functions described may be implemented in one or more nodes using hardware circuitry, e.g., analog and/or discrete logic gates interconnected to perform a specialized function, such as ASICs, Programmable Logic Arrays (PLAs), etc., and/or using software programs and data in conjunction with one or more digital microprocessors or general purpose computers. Nodes that communicate using the air interface also have suitable radio communications circuitry. Moreover, the technology can additionally be embodied within any form of non-transitory, computer-readable memory, such as solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions that would cause one or more processors to carry out the techniques described herein.
Thus, for example, it will be appreciated by those skilled in the art that block diagrams herein can represent conceptual views of illustrative circuitry or other functional units embodying the principles of the technology. Similarly, it will be appreciated that any flow charts, state transition diagrams, pseudocode, and the like represent various processes which may be implemented by computer program instructions that may be stored in a non-transitory, computer-readable storage medium and which when executed by one or more computers or processors cause the processes to be performed, whether or not such computer(s) or processor(s) is(are) explicitly shown.
Hardware implementation may include or encompass, without limitation, digital signal processor (DSP) hardware, a reduced instruction set processor, hardware, e.g., digital or analog, circuitry including but not limited to application specific integrated circuit(s) (ASIC) and/or field programmable gate array(s) (FPGA(s)), and, where appropriate, state machines capable of performing such functions.
In terms of computer implementation, a computer is generally understood to comprise one or more processors or one or more controllers, and the terms computer, processor, and controller may be employed interchangeably. When provided by a computer, processor, or controller, the functions may be provided by a single dedicated computer or processor or controller, by a single shared computer or processor or controller, or by a plurality of individual computers or processors or controllers, some of which may be shared or distributed. Moreover, the term “processor” or “controller” also refers to other hardware capable of performing such functions and/or executing software, such as the example hardware recited above.
The functions of the various elements including functional blocks, including but not limited to those labeled or described as a computer, processor, or controller, may be provided through the use of hardware such as circuit hardware and/or hardware capable of executing software in the form of coded instructions stored on non-transitory, computer-readable medium. Thus, such functions and illustrated functional blocks are to be understood as being either hardware-implemented and/or computer-implemented, and thus machine-implemented.
The technology in this application allows a UE to determine a mobility state of a radio node and use that to intelligently influence the UE's operation. One example of a radio node is a base station. Reference is made to the flowchart diagram in
For purposes of the rest of the application, a small base station is referred to as an access point, AP, and an AP is a Wi-Fi radio base station or any radio base station containing Wi-Fi technology in combination with one or more other type of radio communications technology.
One approach to the problem of non-strategic or undesired handover involving moving APs is to use time hysteresis where an AP is selected for a handover but no handover occurs for a given time period. But the hysteresis approach does not work well for on-board moving AP scenarios. For example, a time hysteresis approach does not cover a situation where a moving AP is temporarily stationary, which happens frequently in, e.g., a bus or taxi scenario where the bus or taxi has stopped for a traffic light or in traffic congestion. With a time hysteresis method, the UE may wait five seconds and then connect to an on-board AP—just in time for the traffic light to turn green and the on-board AP moves out of range. Nor is a longer hysteresis time a better approach. A longer hysteresis time, e.g., 30 seconds, delays the time for the UE to connect to the on-board AP equipment, hence risking poor performance for those UEs. Moreover, a time hysteresis approach does not address the problem of potential overloading of on-board APs from surrounding stationary UEs.
Another approach is to have a Wi-Fi AP declare its “venue status” using information elements that indicate whether the AP is mounted on or otherwise positioned in a vehicle. The Wi-Fi IEEE standard 802.11 specifies a beacon frame as one of the management frames in IEEE 802.11 based Wireless Local Area Networks (WLANs) and it contains information about the network. Beacon frames are transmitted periodically to announce the presence of a Wireless LAN network and are transmitted by the Access Point (AP) in an infrastructure Basic Service Set (BSS). A probe request frame is sent from a station when it requires information from the access point, and after receiving a probe request frame, the AP sends a probe response frame containing capability information, supported data rates, etc. In addition, there are multiple different frames like data frames, control frames, and other management frames. In an infrastructure Wi-Fi network, UEs must associate with an access point to obtain network services. Association is the process by which a UE joins an 802.11 network. UEs always initiate the association process, and access points may choose to grant or deny access based on the contents of an association request. When a UE moves between basic service areas within a single extended service area, it must evaluate signal strength and perhaps switch the access point with which it is associated.
The Wi-Fi Alliance is working on a Hot-Spot 2.0 (HS2.0) initiative, now called PassPoint. HS2.0 is primarily geared toward Wi-Fi networks, and thus, builds on IEEE 802.11u by adding requirements on authentication mechanisms and auto-provisioning support. See IEEE Std 802.11u™-2011, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 9: Interworking with External Networks. Although the current release of HS2.0 is not geared toward 3GPP interworking, it is desirable from a network operator perspective to introduce additional traffic steering capabilities and leveraging HS2.0 802.11u mechanisms that can provide 3GPP interworking requirements. HotSpot 2.0 uses Access Network Query Protocol, ANQP, as part of network discovery and selection. ANQP provides a mechanism for the UE to request different information from an AP before association.
IEEE 802.11u defines AP Venue Information as a 2-octet field that contains Venue Group and Venue Type subfields as shown in
In one example embodiment, an AP may use the venue field to signal its mobility status to the UEs. The venue field does not provide information about whether the AP is actually currently moving or not, e.g., a UE will not know from a received venue field from an AP in a bus, i.e., “venue=bus,” whether the bus is actually moving. For example, a tour bus may be parked for the day (stationary) but still offer Wi-Fi to its bus riders and perhaps others when close to the bus. Although UE may infer from the venue field specifying a vehicle that the AP is mobile, and based on this information, cell (re-)selection and handover decisions may be made. However, the venue field is just one out of multiple possible ways of indicating that an AP is mobile. Other ways of indicating that an AP is mobile include a dedicated signaling message from the AP to a UE either broadcast or sent in unicast from the AP.
Policies may be used to assist and control the access to different types of networks. Inter-System Mobility Policies and Inter-System Routing Policies are described below as examples of policies. Regarding provisioning of policies to UEs, different types of static or dynamic policies can be downloaded to UEs using different mechanisms such as (1) SIM/USIM based policies controlled by the operator and the end user, (2) Device Management (DM) based policies, (3) HotSpot 2.0 policies, and (4) Access Network Discovery and Selection, ANDSF, policies. The cellular network, e.g., 3GPP, defined function ANDSF may be used to send different policies to the UE for network discovery and selection as shown in
More generally, policies are a set of rules that determine if, when, where, and how a UE can access and use Wi-Fi. The rules/policies are typically created and controlled by the operator and signaled to various nodes such as base stations, mobility management nodes, gateways, and UEs. Policies may be used to steer users and UEs to or away from Wi-Fi or cellular service from a particular node depending on location, service used, subscriber identity, subscription type, time of the day, and/or more.
Inter-System Mobility Policies (ISMP) provided to the UE from the ANDSF server are policies which guide the UE to select the most preferable 3GPP or non-3GPP access technology. The ISMP are used for UEs that access a single access, e g 3GPP or Wi-Fi, at a time. Inter-System Routing Policies (ISRP) are policies provided to the UE from the ANDSF server which guide the UE to select over which access a certain type of traffic for example defined per Access Point Name (APN) shall be routed. The ISRP are used for UEs that access both 3GPP and Wi-Fi simultaneously.
The description above shows how Venue Information may be used as an example of a moving AP indication provided from a Wi-Fi AP to a UE using beacon frames, probe response frames, or ANQP signalling along with different examples of provisioning policies to the UE.
The technology described here shows how to use moving AP information, e.g., a venue info element, communicated from an AP to a UE, which contains information about the mobility status, also denoted mobility state, of the AP, to specify how the network, UE, or end-user should act if the AP mobility status indicates that the AP is currently moving. Again, any suitable method that determines the mobility status of a Wi-Fi AP may be used. The Wi-Fi AP may in the following, depending on the circumstances, be referred to as a mobile AP, a moving AP, or just an AP. The Wi-Fi AP is an example of a radio node. According to example embodiments herein, a user equipment may determine a mobility state of the radio node as one of a moving mobility state and a non-moving mobility state, also denoted a standing mobility state. The mobility state may in some embodiments be determined by detecting the Wi-Fi AP and determining whether or not the Wi-Fi AP is a moving AP based on a moving AP indication. The UE may further determine control information relating to UE cell (re-)selection and/or handover behavior based on the determined mobility state of the radio node. The control information may in some embodiments be network-based cell (re-)selection and/or handover control information that may be received from a cellular base station of the network. Additionally or alternatively, the control information may be policies and other information relating to the status, radio conditions, and/or preferences of the UE. The UE may then control its cell (re-)selection and/or handover behavior based on the determined control information.
In a first non-limiting example embodiment, the UE reports the mobility status of the AP to the network as part of its neighbor cell process reporting. The mobility status of the AP is then used as an input to a network-controlled cell-selection procedure. In a second non-limiting example embodiment, a moving AP is included in a list of wireless network connection alternatives provided to a UE user. The user decides whether to accept connecting to the mobile access point. For example, a user-controllable setting in a UE may be configured not to connect to moving access points unless the end-user manually allows or selects the connectivity when entering a train or a bus. In a third non-limiting, example embodiment, policies configured in the UE by the network operator are enhanced to also take into account the “moving AP” indication.
In the first example embodiment, a first implementation example alternative is for an AP to broadcast a “moving AP” indication as part of broadcast system information. For example, the UE may report to the network the mobility status of the AP as part of the UE's neighbor cell reporting, and the network acts on this AP mobility information as part of a network controlled cell selection procedure for the UE. A node in the network for example avoids instructing the UE to select or switch to the mobile AP unless and until the network node discovers information that indicates that the UE is moving with the moving AP. Examples of such a node include a base station, a radio network controller, a base station controller, a dedicated mobility server, etc.
A second example embodiment provides an end user controllable handling of “Moving AP” indication. In case of terminal controlled cell selection, a moving AP indication would be used by the terminal to decide whether or not to connect to the cell. This could result either in displaying the access point as mobile and let the subscriber manually decide whether or not to connect to it, or result in a pre-defined end-user controlled mobile behavior like automatically avoiding connecting unless certain other criteria are met like the UE measuring its own speed to match that of the moving base station.
Still other aspects of the technology include one or more computer products embodied in a non-transitory, computer-readable storage medium containing instructions, which when executed by processing circuitry, perform the functions described above for the AP and UE. For example, one non-transitory, computer-readable storage medium is configured for use with an AP, and another non-transitory, computer-readable storage medium is configured for use with UEs.
Various other example mechanisms to identify or determine the mobility state of a mobile AP are described in commonly-assigned patent application entitled “Mobility State Aware Mobile Relay Operation,” U.S. Provisional Application No. 61/523,973, the disclosure of which is incorporated herein by reference, may be used to identify the mobility state of an AP.
The technology described above offers a number of example advantages in a situation where a UE may communicate with both cellular base stations and Wi-Fi access points. First, the UE is actively informed that an AP or other type of base station is a moving AP. This information allows the UE and/or the UE user to make an informed decision about whether to connect to that AP. Second, being so informed helps prevent overloading a moving AP on-board a moving vehicle from being overloaded by stationary UEs, e.g., while the AP moves through busy areas. Third, the technology described above prevents a potentially very large amount of mobility signaling from stationary UEs connecting and disconnecting from a moving AP within a short period of time, i.e., ping pong handovers. Fourth, the technology decreases the risk for poor performance for stationary UEs associated with cell (re-)selection and/or handovers resulting from connect and disconnect to a moving AP.
Although the description above contains many specifics, these should not be construed as limiting the scope of the claims but as merely providing illustrations of example embodiments. It will be appreciated that the technology claimed fully encompasses other embodiments which may become apparent to those skilled in the art, and that the scope of the claims is accordingly not to be limited. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are intended to be encompassed hereby. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved for it to be encompassed hereby. No element, block, or instruction used in the present application should be construed as critical or essential to the implementations described herein unless explicitly described as such. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Unclaimed subject matter is not dedicated to the public, and all rights are reserved in unclaimed subject matter including the right to claim such subject matter in this and other applications, e.g., continuations, continuations in part, divisions, etc.
This nonprovisional application is a National Stage Filing under 35 U.S.C. §371 of International Patent Application Serial No. PCT/SE2012/050879, filed Aug. 16, 2012 and entitled “Moving Access Point Indication,” which claims the benefit of U.S. Provisional Application No. 61/523,973, filed Aug. 16, 2011 and entitled “Mobility State Aware Mobile Relay Operation.”
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PCT/SE2012/050879 | 8/16/2012 | WO | 00 | 2/14/2014 |
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WO2013/025168 | 2/21/2013 | WO | A |
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