1. Field of the Disclosure
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to techniques for routing data bearers of a user equipment (UE) while the UE is handing over or associating to a base station (BS) of a first radio access technology (RAT) while being served by a BS of a second RAT.
2. Description of the Related Art
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, Long Term Evolution Advanced (LTE-A) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-input single-output, multiple-input single-output or a multiple-input multiple-output (MIMO) system.
As wireless communication technology advances, a growing number of different radio access technologies are being utilized. For instance, many geographic areas are now served by multiple wireless communication systems, each of which can utilize one or more different air interface technologies. In order to increase versatility of wireless terminals in such a network environment, there recently has been an increasing trend toward multi-mode wireless terminals that are able to operate under multiple radio technologies. For example, a multi-mode implementation can enable a terminal to select a system from among multiple systems in a geographic area, each of which may utilize different radio interface technologies, and subsequently communicate with one or more chosen systems.
In some cases, such a system may allow traffic to be offloaded from one network, such as a wireless wide area network (WWAN) to a second network, such as a wireless local area network (WLAN).
Certain aspects of the present disclosure provide a method for wireless communications performed by a base station (BS) of a first radio access technology (RAT). The method generally includes identifying a plurality of data bearers configured for a user equipment (UE) served by a first base station of a second RAT, receiving from the UE a measurement report identifying a second base station of the second RAT, identifying one or more of the data bearers to offload to the second base station of the second RAT based on the measurement report, communicating with the first and second base stations of the second RAT to offload the identified data bearers to the second base station of the second RAT, and configuring the UE to use the second base station of the second RAT for transmitting and receiving the identified bearers.
Certain aspects of the present disclosure provide a method for wireless communications performed by a base station (BS) of a first radio access technology (RAT). The method generally includes receiving from a user equipment (UE), a measurement report identifying a target base station of the first RAT, determining the UE is interworking with a base station of a second RAT, sending a handover request to the target base station, the handover request including information identifying the base station of the second RAT and at least one data bearer configured for the UE served by the base station of the second RAT, configuring the UE to handover to the target base station while keeping interworking with the base station of the second RAT, forwarding data for the identified at least one data bearer to the target base station until the handover is complete, and sending an indication to the target base station that the base station is ending forwarding data for the identified at least one data bearer to the target base station.
Certain aspects of the present disclosure provide a method for wireless communications performed by a base station (BS) of a first radio access technology (RAT). The method generally includes receiving a handover request from a source base station of the first RAT to handover a user equipment (UE), the handover request including information identifying a base station of a second RAT and at least one data bearer configured for the UE served by the base station of the second RAT, receiving data for the identified at least one data bearer from the source base station until the handover is complete, and sending a request to offload the at least one identified data bearer to the base station of the second RAT.
Certain aspects of the present disclosure provide an apparatus for wireless communications of a first radio access technology (RAT). The apparatus generally includes a processor configured to identify a plurality of data bearers configured for a user equipment (UE) served by a first base station of a second RAT, receive from the UE a measurement report identifying a second base station of the second RAT, identify one or more of the data bearers to offload to the second base station of the second RAT based on the measurement report, communicate with the first and second base stations of the second RAT to offload the identified data bearers to the second base station of the second RAT, and configure the UE to use the second base station of the second RAT for transmitting and receiving the identified bearers, and a memory coupled with the processor.
Certain aspects of the present disclosure provide an apparatus for wireless communications of a first radio access technology (RAT). The apparatus generally includes a processor configured to receive, from a user equipment (UE), a measurement report identifying a target base station of the first RAT, determine the UE is interworking with a base station of a second RAT, send a handover request to the target base station, the handover request including information identifying the base station of the second RAT and at least one data bearer configured for the UE served by the base station of the second RAT, configure the UE to handover to the target base station while keeping interworking with the base station of the second RAT, forward data for the identified at least one data bearer to the target base station until the handover is complete, and send an indication to the target base station that the base station is ending forwarding data for the identified at least one data bearer to the target base station, and a memory coupled with the processor.
Certain aspects of the present disclosure provide an apparatus for wireless communications of a first radio access technology (RAT). The apparatus generally includes a processor configured to receive a handover request from a source base station of the first RAT to handover a user equipment (UE), the handover request including information identifying a base station of a second RAT and at least one data bearer configured for the UE served by the base station of the second RAT, receive data for the identified at least one data bearer from the source base station until the handover is complete, and send a request to offload the at least one identified data bearer to the base station of the second RAT, and a memory coupled with the processor.
Various aspects and features of the disclosure are described in further detail below.
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.
As demand for wireless services increases, network operators may desire to offload user device traffic from a cellular network to a wireless local area network (WLAN), for example, a Wi-Fi WLAN, to reduce congestion on the cellular network, and because operator deployed WLANs are often under-utilized. However, the experience of users is suboptimal when a UE connects to an overloaded WLAN. According to aspects of the present disclosure, network operators may control which traffic is routed over WLAN and which traffic is kept on the WWAN (e.g., 3GPP RAN). For example, some data flows (e.g., related to VoIP or other operators' services) can be served on WWAN to leverage its QoS capabilities, while data flows related to “best-effort” Internet traffic can be offloaded to WLAN. According to certain aspects of the present disclosure, an interface for controlling interfacing methods and apparatus are provided to enable network operators to control which network traffic is routed over WLAN (e.g., a Wi-Fi WLAN) and which traffic is kept on the WWAN. For controlling offloading between LTE and Wi-Fi, an interface called Xw is disclosed.
Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.
Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.
The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). CDMA2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE Std 802.11, IEEE Std 802.16, IEEE Std 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2).
Single carrier frequency division multiple access (SC-FDMA) is a transmission technique that utilizes single carrier modulation at a transmitter side and frequency domain equalization at a receiver side. The SC-FDMA has similar performance and essentially the same overall complexity as those of OFDMA system. However, SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. The SC-FDMA has drawn great attention, especially in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. It is currently a working assumption for uplink multiple access scheme in the 3GPP LTE and the Evolved UTRA.
An access point (“AP”) may comprise, be implemented as, or known as NodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller (“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station (“RBS”), or some other terminology.
An access terminal (“AT”) may comprise, be implemented as, or known as an access terminal, a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, user equipment, a user station, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (“SIP”) phone, a wireless local loop (“WLL”) station, a personal digital assistant (“PDA”), a handheld device having wireless connection capability, a Station (“STA”), or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. In some aspects, the node is a wireless node. Such wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.
Referring to
Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point. In one aspect of the present disclosure, each antenna group may be designed to communicate to access terminals in a sector of the areas covered by access point 100.
In communication over forward links 120 and 126, the transmitting antennas of access point 100 may utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals 116 and 122. Also, an access point using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access point transmitting through a single antenna to all its access terminals.
In one aspect of the present disclosure, each data stream may be transmitted over a respective transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.
The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 230. Memory 232 may store data and software for the transmitter system 210.
The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor 220 then provides NT modulation symbol streams to NT transmitters (TMTR) 222a through 222t. In certain aspects of the present disclosure, TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.
Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from transmitters 222a through 222t are then transmitted from NT antennas 224a through 224t, respectively.
At receiver system 250, the transmitted modulated signals may be received by NR antennas 252a through 252r and the received signal from each antenna 252 may be provided to a respective receiver (RCVR) 254a through 254r. Each receiver 254 may condition (e.g., filters, amplifies, and downconverts) a respective received signal, digitize the conditioned signal to provide samples, and further process the samples to provide a corresponding “received” symbol stream.
An RX data processor 260 then receives and processes the NR received symbol streams from NR receivers 254 based on a particular receiver processing technique to provide NT “detected” symbol streams. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 260 may be complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210.
A processor 270 periodically determines which pre-coding matrix to use. Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion. Memory 272 may store data and software for the receiver system 250. The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by a modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to transmitter system 210.
At transmitter system 210, the modulated signals from receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by a RX data processor 242 to extract the reserve link message transmitted by the receiver system 250. Processor 230 then determines which pre-coding matrix to use for determining the beamforming weights, and then processes the extracted message.
The wireless device 302 may include a processor 304 that controls operation of the wireless device 302. The processor 304 may also be referred to as a central processing unit (CPU). Memory 306, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor 304. A portion of the memory 306 may also include non-volatile random access memory (NVRAM). The processor 304 typically performs logical and arithmetic operations based on program instructions stored within the memory 306. The processor 304 may direct the operation of wireless device 302 in performing the methods described herein and set forth in
The wireless device 302 may also include a housing 308 that may include a transmitter 310 and a receiver 312 to allow transmission and reception of data between the wireless device 302 and a remote location. The transmitter 310 and receiver 312 may be combined into a transceiver 314. A single transmit antenna 316 or a plurality of transmit antennas 316 may be attached to the housing 308 and electrically coupled to the transceiver 314. The wireless device 302 may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.
The wireless device 302 may also include a signal detector 318 that may be used in an effort to detect and quantify the level of signals received by the transceiver 314. The signal detector 318 may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals. The wireless device 302 may also include a digital signal processor (DSP) 320 for use in processing signals.
The various components of the wireless device 302 may be coupled together by a bus system 322, which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus.
In order to expand the services available to subscribers, some mobile stations (MS) support communications with multiple radio access technologies (RATs). For example, as illustrated in
In certain applications, multi-RAT interface logic 430 may be used to exchange information between both long-range and short-range RATs. This may enable a network provider to control how (through which RAT) an end user of the multi-mode MS 410 actually connects to the network. The interface logic 430 may, for example, support local IP connectivity or IP connectivity to a core network.
For example, a network provider may be able to direct the multi-mode MS to connect to the network via short-range RAT, when available. This capability may allow a network provider to route traffic in a manner that eases congestion of particular air resources. In effect, the network provider may use short-range RATs to distribute some air traffic (of a long-range RAT) into a wireline network or to distribute some air traffic from a congested wireless network to a less congested wireless network. The traffic may be re-routed from the short-range RAT when conditions mandate, such as when a mobile user increases speed to a certain level not suitable for a short-range RAT.
Further, since long-range RATs are typically designed to provide service over several kilometers, the power consumption of transmissions from a multi-mode MS when using a long-range RAT is non-trivial. In contrast, short-range RATs (e.g., Wi-Fi) are designed to provide service over several hundred meters. Accordingly, utilizing a short-range RAT, when available, may result in less power consumption by the multi-mode MS 410 and, consequently, longer battery life.
As illustrated in
According to certain aspects, the BS of the wide-area network may communicate with a mobility management entity (MME) 510 in the core network via an S1-MME interface, and with a serving gateway (SGW) 512 via an S1-U interface. The BS of the local-area network may communicate with an evolved packet data gateway (ePDG) or trusted wireless access gateway (TWAG) in the core network via S2a and/or S2b interfaces. The MME may communicate with a home subscriber server (HSS) 514 via an S6a interface, and with the serving gateway via an S11 interface. The SGW may communicate with a packet gateway (PGW) 516 via an S5 interface. The PGW may communicate with Internet entities via an SGi interface.
According to certain aspects of the present disclosure, the BS of the wide-area network 504 may communicate with the BS of the local-area network 502 via an Xw interface, as described herein.
According to certain aspects, with RAN aggregation a user may be simultaneously connected to an LTE eNB and a WLAN AP (e.g., a Wi-Fi AP), which provide radio access links to transport a user's signaling and data traffic, as shown in
A UE may become aware of WLAN APs by performing scanning procedures as specified in IEEE Std 802.11, which generally includes passive scanning and active scanning. Passive scanning, as defined in IEEE Std 802.11, may be inefficient for the UE, as it waits, with receiver on, for the reception of a WLAN beacon. As the beacon transmission interval is approximately a hundred milliseconds, passive scanning for WLAN beacons on dozens of possible WLAN channels may result in high scan energy and high scan latency. Active scanning may be faster, but adds traffic to the WLAN, namely probe requests and probe responses. Active scanning is also power intensive.
IEEE Std 802.11u has defined additional mechanisms for a UE to discover further information about an AP without being associated with the AP. For example, a generic advertisement service (GAS) may provide a transport of an advertisement protocol's frames between the UE and a server in the network. The AP may be responsible for the relay of a mobile device's query to a server in the carrier's network and for delivering the server's response back to the mobile. An example of another mechanism includes access network query protocol (ANQP), which is generally a query advertisement protocol for access network information retrieval by the UE/STA from the AP which is transported over the generic advertisement service (GAS), including a Hotspot operator's domain name, roaming partners accessible via the Hotspot along with their credential type and EAP method supported for authentication, IP address type availability, and other metadata useful in the UE's network selection process.
A UE may not have to associate with a WLAN AP in order to provide measurements. The UE may support a subset of additional procedures as defined in IEEE Std 802.11k, IEEE Std 802.11u and Hotspot 2.0. With regards to a radio access network (RAN), there may be no interface between the AP and the eNodeB, as illustrated in
In general, offloading traffic from a cellular network to a WLAN may be desirable, because operator deployed WLAN networks are often under-utilized. However, user experience is suboptimal when a UE connects to an overloaded WLAN. Aspects of the present disclosure may be utilized by mobile operators to control which traffic is routed over WLAN and which traffic is kept on the WWAN (e.g., 3GPP RAN). For example, some data flows (e.g., related to VoIP or other operators' services) can be served on WWAN to leverage its QoS capabilities, while data flows related to “best-effort” Internet traffic can be offloaded to WLAN.
According to certain aspects, a user may be simultaneously connected to an LTE eNB and a Wi-Fi AP, which provide radio access links to transport a user's signaling and data traffic, as shown in
Data or signaling bearers of a UE, such as the UE illustrated in
For purposes of clarity, the below disclosure is described with regard to a UE with logically collocated LTE and WLAN STA functions (e.g., an LTE mobile phone with Wi-Fi capability, wherein the LTE and Wi-Fi interfaces are controlled by a single controller/processor), but the disclosure is not limited to UEs with logically collocated LTE and WLAN STA functions.
According to certain aspects, an interface, referred to as Xw, may be implemented between eNBs and WLAN APs. The Xw interface comprises a user plane (Xw-U) and a control plane (Xw-C). Xw-U may be used to forward data packets between an eNB and a WLAN AP, where each packet belongs to a data bearer. Xw-C may be used to transmit control messages between an eNB and a WLAN AP for interface selection decisions for data bearers, for mobility, and for exchanging resource and performance information. When an AP is an LTE eNB, X2 interface may be used (e.g., for communicating data packets and control messages) instead of the Xw interface.
According to certain aspects, the Xw-C control plane can be implemented between an eNB and an AP without the Xw-U user plane being implemented between the eNB and the AP, e.g., where an AP is connected directly to a core network. User data to be transported to or from a UE via the AP could be received directly from the core network or transmitted directly to the core network via the direct connection, and there may be no need for the Xw-U plane.
According to certain aspects, when an Xw-U user plane is implemented between an eNB and a WLAN AP, the eNB functions as an anchor point for RAN bearers and forwards packets for these bearers to and from the WLAN AP. In other words, all of the data for the offloaded bearers transits via the eNB, either from a UE via the AP to the eNB and sent on to the core network, or from the core network to the eNB, sent on to the AP, and delivered to the UE by the AP.
Access to PDN services and associated applications in a wireless network may be provided to a UE by EPS bearers. A default bearer for the UE is typically established during attachment of the UE to the PDN. The default bearer for the UE may be maintained throughout the lifetime of the connection between the UE and PDN. This may be referred to as always-on IP connectivity. Because of access to services by the UE or service requests, additional dedicated bearers can be dynamically established. A dedicated bearer may be used if the end-user has connectivity to a different Packet Data Network (PDN) than that provided by the default bearer, or if the end-user uses a different Quality of Service (QoS) than that offered by the default bearer. Dedicated bearers are configured to run in parallel to the existing default bearer.
According to certain aspects, the following two procedures over the Xw interface may be used for data offloading and handover: the INITIAL BEARER OFFLOAD procedure and the MODIFY BEARER OFFLOAD procedure. The INITIAL BEARER OFFLOAD procedure may be used to begin offloading of a bearer currently being served via a WWAN base station (e.g., an eNB) to a WLAN base station (e.g., a Wi-Fi AP). The MODIFY BEARER OFFLOAD procedure may be used to request adding or deleting data bearers to the data bearers for a UE offloaded from a WWAN base station to a WLAN base station (e.g., the UE was previously associated with an INITIAL BEARER OFFLOAD procedure).
According to certain aspects, the INITIAL BEARER OFFLOAD procedure may be used by an eNB to request offloading of bearers for a UE to an AP for the first time after the UE associates with the AP, as described herein.
According to certain aspects, the MODIFY BEARER OFFLOAD procedure may be used by an eNB to request adding or deleting data bearers to the data bearers for a UE offloaded to an AP, as described herein.
For purposes of clarity, LTE handover and WLAN handover procedures are treated as independent and decoupled in this disclosure, but the disclosed methods and apparatuses are not so limited. For example, the INITIAL BEARER OFFLOAD procedure and MODIFY BEARER OFFLOAD procedure may be used in a network wherein an LTE handover triggers the network to begin a WLAN handover.
According to certain aspects, the LTE mobility procedure may be unchanged from previous standards (e.g., Rel-8), except for new Wi-Fi related information in the X2 messages as described below. Wi-Fi mobility may be UE driven; i.e. the UE may autonomously associate and disassociate with APs and report these association changes to a serving eNB, which may make data traffic routing decisions based on the association changes. For example, a UE served by an eNB may have a data bearer offloaded to a first AP when the UE moves, dissociates from the first AP, and associates to a second AP. In the example, the UE reports the dissociation from the first AP and the association to the second AP, and the eNB uses the MODIFY BEARER OFFLOAD procedure with the first AP to stop offloading of bearers with the first AP and the INITIAL BEARER OFFLOAD procedure to begin offloading of bearers with the second AP.
According to certain aspects, a UE may make autonomous decisions for association with an AP and report the association to a serving eNB in an Association Report. The Association Report may include measurements for the AP. For example, a UE may include signal strength measurements for a newly associated AP in an Association Report to the UE's serving eNB. According to certain aspects, an eNB may make decisions for offloading a UE's data bearers to an AP based on UE measurement reports regarding the AP. In the example, the UE may report that it is receiving a relatively high signal strength from the AP, and the eNB may determine to offload data bearers for the UE to the AP based on the reported signal strength.
According to certain aspects, an eNB may request offloading to an AP over the Xw interface and, after getting a positive response, the eNB may configure the UE, via RRC signaling, to offload some or all of the UE's data bearers. For example, an eNB may send an INITIAL BEARER OFFLOAD REQUEST message to an AP requesting offloading of a default bearer of a UE to the AP. In the example, the INITIAL BEARER OFFLOAD REQUEST message includes an identifier of the UE and an identifier of the default bearer. Also in the example, the AP may determine that it will admit the UE's default bearer, and send an INITIAL BEARER OFFLOAD RESPONSE message to the eNB indicating that the AP will admit the UE's default bearer. Still in the example, the eNB will then send RRC signaling to the UE to offload the UE's default bearer to the AP.
Referring to the call flow in
Still referring to the call flow in
The exemplary call flow 1000 in
According to certain aspects, for an eNB to eNB handover of a UE that is participating in interworking with an eNB and an AP, the source eNB may communicate with the target eNB over an X2 interface following standard (e.g., Rel-8) LTE handover procedures. However, the following differences from a standard LTE handover are disclosed:
According to certain aspects, the configured traffic offloading at an AP may be kept until the LTE handover is complete, i.e., the configuration of data bearers at the AP may not change during the LTE handover. The UE may still transmit to the Wi-Fi AP on the data bearers configured by the source eNB, and the Wi-Fi AP may transmit the traffic for this UE received from the source eNB.
According to certain aspects, after the handover is successful (e.g., HO Complete message is received by the target eNB), the target eNB may configure offloading with the AP based on the information obtained from the source eNB. If the target eNB keeps the same set of offloaded data bearers at the AP, no new RRC configuration may be needed for the UE. If the target eNB changes the offloaded data bearers during the INITIAL BEARER OFFLOAD procedure with the AP, the target eNB may send a RRC reconfiguration message to the UE.
According to certain aspects, the source eNB may keep forwarding traffic for offloaded data bearers to the AP until the source eNB receives an indication that S1-U bearers for the offloaded traffic have been switched to the target eNB. The source eNB may then stop forwarding packets to both the target eNB and the AP.
In the call flow illustrated in
According to certain aspects, if a radio link failure (RLF) happens, either at the source or the target eNB, the UE may suspend all bearers and reselect a new cell. The new cell may reconfigure the data bearer offloading with the AP by using the operations described herein.
The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in Figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.
As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.
As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
The various operations of methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software component(s), circuits, and/or module(s). Generally, any operations illustrated in the Figures may be performed by corresponding functional means capable of performing the operations.
The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, e.g., 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 described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM and so forth. A software module may comprise a single instruction or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. A storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.
The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.
The functions described may be implemented in hardware, software, firmware or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.
Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging material.
Software or instructions may also be transmitted over a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium.
Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.
It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.
While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
The present Application for Patent claims priority to U.S. Provisional Application No. 61/892,971, filed Oct. 18, 2013, which is assigned to the assignee of the present application and hereby expressly incorporated by reference herein in its entirety.
Number | Date | Country | |
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61892971 | Oct 2013 | US |