Traffic Engineering in Heterogeneous Millimeter Wave and LTE Small Cell Systems

Abstract

This disclosure relates to traffic engineering in a heterogeneous mmWave and LTE small cell system. This disclosure describes traffic engineering functionality in a heterogeneous network consisting of an anchor base station serving a cellular macrocell and a booster base station serving a mmWave-enabled small cell. The described functionality is designed to cope with dynamic changes in the heterogeneous environment, such as loss of the backhaul link between the anchor base station and the booster base station, loss of the link between a terminal and one of the base stations, and loss of beamforming in the mmWave link between the terminal and the booster base station.

Description

[0001] This patent application is a divisional application of a patent application filed on November 13, 2015, with application number 201580062352.2 and invention name “Traffic Engineering in Heterogeneous Millimeter Wave and LTE Small Cell Systems”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims priority to U.S. patent application serial number 14 / 577,766, filed December 19, 2014, which is hereby incorporated by reference in its entirety. Technical Field

[0004] Embodiments relate to wireless communications. Certain embodiments relate to cellular networks, including networks operating in accordance with 3GPP LTE and LTE-A standards. Certain embodiments relate to small cell deployments. Certain embodiments relate to 5G cellular networks. Background Art

[0005] A heterogeneous cellular communication network may include a macro cell layer accompanied by an additional small cell layer. For example, in LTE / LTE-Advanced (Long Term Evolution) deployments, a terminal (referred to as a UE or user equipment) can connect to a macro cell served by a base station (eNB or evolved NodeB LTE) and to a small cell served by a small eNB, where the macro cell and the small cell overlap. These additional small cells may be deployed primarily for capacity improvement (e.g., in traffic hotspots) or for coverage enhancement (e.g., at the edge of the macro cell or in coverage holes in the macro cell layer, such as subway stations, shopping malls, etc.). Summary of the Invention

[0006] A first aspect of the present disclosure relates to a method for operating a user equipment (UE) device, comprising: communicating with a first base station on a first radio link using Long Term Evolution (LTE) radio access technology (RAT); communicating with a second base station on a second radio link using millimeter wave, i.e., mmWave, RAT, wherein the second radio link includes beamforming between the second base station and the UE; sending control plane data on the first radio link using the LTE RAT, wherein primary control plane functions are performed on the first radio link; sending user plane data on the second radio link primarily using the mmWave RAT; and when the second radio link between the UE and the second base station fails, sending an indication of the failure of the second radio link to the first base station on the first radio link to trigger one or more support functions of the first base station or the second base station.

[0007] A second aspect of the present disclosure relates to a user equipment (UE) device, comprising: a first radio transceiver for providing a long term evolution (LTE) interface, the LTE interface being used to communicate with a first base station on a first wireless link; a second radio transceiver for providing a millimeter wave (mmWave) interface, the mmWave interface being used to communicate with a second base station on a second wireless link, wherein the second wireless link includes beamforming between the second base station and the UE; and a processing circuit configured to: send control plane data on the first wireless link using the LTE RAT, wherein primary control plane functions are performed on the first wireless link; send user plane data on the second wireless link primarily using the mmWave RAT; and when the second wireless link between the UE and the second base station fails, send an indication of the failure of the second wireless link to the first base station on the first wireless link to trigger one or more support functions of the first base station or the second base station.

[0008] A third aspect of the present disclosure relates to a non-transitory computer-readable storage medium storing instructions for execution by one or more processors of a user equipment (UE) to perform operations to configure the UE to perform a method according to the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Illustrated are components of a heterogeneous mmWave and LTE network in accordance with certain embodiments.

[0010] Figure 2 An example of a heterogeneous network deployment of a capacity-enhancing type in accordance with certain embodiments is illustrated.

[0011] Figure 3 An example of a coverage extension type heterogeneous network deployment is illustrated in accordance with certain embodiments.

[0012] Figure 4A and 4B Tables illustrating examples of anchor eNB and enhancement eNB functionality for capacity enhancement and coverage extension types of deployments, respectively, according to certain embodiments.

[0013] Figures 5A to 5C Illustrated is an example of LTE-assisted network operation as a UE moves into the coverage area of ​​an enhanced eNB in ​​accordance with certain embodiments. DETAILED DESCRIPTION

[0014] The following description and accompanying drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical processes, and other variations. Portions and features of some embodiments may be included in or substituted for those of other embodiments. The embodiments set forth in the claims include all available equivalents of those claims.

[0015] In a heterogeneous network including macro cells and small cells, the small cell layer can be served by small, low-power base stations that can be installed, for example, on street furniture and the like. Small cell base stations (also referred to as "enhanced eNBs" or simply "boosters") can provide access links to mobile devices (LTE-compliant UEs) that use LTE radio access technology, mmWave (millimeter wave) technology, or both. For example, the enhanced eNB can be equipped with a mmWave interface and can also be referred to as a mmWave-capable small cell (MCSC). The base station serving the macro cell can be referred to as an anchor eNB connected to the enhanced eNB via a backhaul link.

[0016] The problem with heterogeneous MCSCs stems from the numerous deployment options and the fact that capabilities are not static due to the propagation characteristics of mmWave links. Prior art systems treat backhaul links as static and therefore do not account for configuration changes during operation. Mobility aspects and RRC (Radio Resource Control) signaling requirements are very different in MCSCs, and the known separation of the U (user) and C (control) planes requires enhanced traffic engineering procedures to avoid excessive mobility procedures.

[0017] Figure 1The diagram illustrates an example of components of a heterogeneous mmWave and LTE network consisting of a UE 100, an enhanced eNB 200, and an anchor eNB 300. The UE 100 includes processing circuitry 101 connected to an LTE transceiver 102 to provide an LTE interface and to a mmWave transceiver to provide a mmWave interface. The enhanced eNB 200 includes processing circuitry 201 connected to an LTE transceiver 202 to provide an LTE interface and to a mmWave transceiver 203 to provide a mmWave interface. The anchor eNB 300 includes processing circuitry 301 connected to an LTE transceiver 302 to provide an LTE interface. Each of the transceivers in these devices is connected to an antenna 50 that can operate as a directional array (i.e., beamforming). In particular, the mmWave interface requires beamforming to achieve sufficient data transmission rates and sufficient coverage area. Before beamforming is established, the mmWave interface of the UE 100 and enhanced eNB 200 can utilize a control mode in which the antenna 50 operates as an omnidirectional array. In the control mode, the UE 100 and the enhanced eNB 200 exchange information to allow subsequent operation in the beamforming mode with a higher data rate.

[0018] Figure 2 The diagram illustrates the coverage area of ​​heterogeneous mmWave and LTE networks in an example scenario where macro cells overlap with small cells. The macro cell base station used as the attachment point for the enhanced eNB of the cellular network can be referred to as an "anchor eNB" or simply "anchor". The anchor eNB 300 is connected to the core network 400 (Evolved Packet Core or EPC in LTE terminology) via the S1 interface and communicates with the UE 100 via the LTE air interface. A backhaul link (e.g., an X2 interface) connects the anchor eNB 300 to the enhanced eNB 200. The backhaul link between the enhanced eNB 200 and the anchor eNB 300 can be a single point-to-point connection between the enhancer and the anchor, or it can be a multi-hop connection with multiple intermediate relay nodes. The enhancer can also be associated to the anchor via parallel links, which allows network coding to be applied. The enhanced eNB 200 communicates with the UE 100 via the LTE interface and / or the mmWave interface. Because the coverage area of ​​the enhancer eNB 200 is contained within the coverage area of ​​the anchor eNB 300, this scenario can be referred to as a capacity enhancement type of deployment. Figure 3 The diagram illustrates different scenarios in which part of the coverage area of ​​the booster eNB 200 is outside the coverage area of ​​the anchor eNB 300. Furthermore, there may be no link between the anchor eNB 300 and the UE 100 and / or the booster eNB 200. This type of scenario may be referred to as a coverage extension type of deployment. Certain scenarios may incorporate aspects of both coverage extension and capacity enhancement deployments.

[0019] Described herein is traffic engineering functionality in a heterogeneous network comprising an anchor serving a cellular macrocell and a booster serving a mmWave-enabled small cell designed to cope with dynamic changes in the heterogeneous environment. Changes of various dynamic natures may occur, ranging from short- to medium-term changes in channel propagation conditions, such as rainfall, to long-term fading effects. They may also occur intentionally, from long-term changes in network setup to medium-term effects of energy saving mechanisms applied in the network. Among the parameters describing the dynamic, transient heterogeneous environment that may vary in time and result in the network having to cope with are the following: 1) the availability of an anchor-booster-link (e.g., mmWave-based); 2) the availability of an anchor cell (macrocell) at the UE currently served by the booster; 3) the possibility of established beamforming functionality between the UE and the booster; and 4) the availability of a control mode link between the UE and the booster (absent beamforming).

[0020] In addition to the dynamic changes in heterogeneous environments mentioned above, traffic engineering functionality can also be affected by the following factors that describe the available network setup. The first factor is whether the MCSC is deployed for coverage extension or capacity improvement. Figure 3 In the case of coverage extension deployment (i.e., adding coverage to areas where the cellular system does not provide basic services), the enhancement eNB does not necessarily have a connection to the anchor eNB (assuming that the separation of user plane and control plane traffic is not within the scope of coverage extension deployment). In addition, the dynamic changes in the macro cell to MCSC link may have a lower impact in the case of coverage extension deployment. On the other hand, for example, Figure 2 In the capacity-enhancing deployment illustrated in Figure 1, the enhanced eNB, by definition, has a connection to the anchor eNB, and dynamic changes in the macrocell-to-MCSC link have a higher impact. A second factor is whether the control and user planes between the enhanced eNB and the anchor eNB are separated for MCSC deployments for capacity enhancement. A third factor is whether the enhanced eNB has the ability to provide the LTE air interface (Uu interface in 3GPP terminology) to serve UEs.

[0021] Depending on the network configuration according to the dynamic parameters and network setup factors mentioned above, different alternatives emerge to divide the functionality and traffic between the anchor eNB and the enhanced eNB. Figure 4A and 4B 1 and 2 to illustrate different alternatives for dividing functionality between anchor eNB and enhance eNB depending on the aforementioned factors. Figure 4A The table in is applied to capacity-oriented MCSC, while Figure 4B The table in [1] applies to coverage-oriented MCSC. For capacity-oriented MCSC, the anchor eNB should be able to dynamically reconfigure the enhanced eNB to Figure 4AFor coverage-oriented eNB, the enhanced eNB should autonomously Figure 4B to reconfigure itself using the features described in Figure 4A and 4B An important feature that should be noted in the

[15] is the possibility of using the LTE Uu air interface at the anchor eNB or enhanced eNB to support mmWave link functionality. That is, the traditional LTE Uu air interface can be used for mmWave link establishment, maintenance, and termination through the exchange of (c-plane) information, which is accompanied by the separation of user plane and control plane traffic. Given that the control mode of the mmWave link uses a lower rate to compensate for the lack of antenna gain, it becomes extremely important to quickly establish a beamforming link between the UE and the mmWave interface of the enhanced eNB. This establishment operation can be supported by the LTE interface and will therefore be significantly accelerated.

[0022] Examples of dynamically changing events that affect the network and countermeasures for handling those events will now be described. Events will be referred to by the following indications. Event ABL- is when the mmWave-based anchor-booster-link is lost or the quality is below a threshold (e.g., beamforming is lost due to loss of LOS (line of sight) or the presence of strong interference). Event ABL+ is when the mmWave-based anchor-booster-link becomes available. Event UAL- is when the LTE-based macro link (UE to macro cell) is lost or the quality is below a threshold (e.g., the physical link suffers severe attenuation or cell overload occurs, the UE antenna is covered, or the UE at the cell edge leaves the macro cell without reselection). Event UAL+ is when the LTE-based macro link (UE to macro cell) becomes available. Event UBL- is when the UE to booster link is completely lost and no control mode link is available (e.g., due to strong interference), and event UBL+ is when the UE to booster control mode link becomes available. Event UBBf- is when the high data rate UE to booster link (with beamforming functionality) is lost, but the control mode link is still available (e.g., beam tracking fails due to unexpected UE movement). Event UBBf+ is when a high data rate UE to booster link (with beamforming functionality) is established from the control mode link.

[0023] Events ABL-, UBbf-

[0024] A similar impact on UE data transmission and reception occurs in capacity improvement type deployments when the mmWave based anchor-booster-link is lost or the high data rate UE to booster link (with beamforming functionality) is lost but the control mode link is still available. The path from the UE to the anchor via the booster is unavailable in both events, and a quick resolution of the situation is desired for the following reasons: 1) the anchor-booster-link is expected to be generally available (booster has no mobility, almost LOS) so that after the link is lost, re-establishment can be expected quickly; and 2) if the mmWave beamforming between the booster and the UE fails but the control link is still available, the beamforming (and thus the high data rate capability of the link) is expected to be re-established quickly. If beamforming is lost but the control link between the UE and the booster is still available, re-establishment of the beamforming is of the highest priority to restore the efficiency of the mmWave link. If a parallel LTE link is maintained to the booster or macro station (for C-plane data in the case of C- / U-plane split, or for other purposes), the UE can immediately notify the booster and / or anchor of the loss of beamforming to trigger support functions from the booster or macro station over LTE to restore beamforming. The booster eNB that detects the loss of beamforming for the UE can also do so if support via LTE is expected from the macro station: the booster can notify the macro station of the need to contact the UE via LTE to quickly restore beamforming. There are three possible options for the handling of data to be transmitted on the lost mmWave link: 1) buffering the data to be transmitted on the link (uplink buffering in the UE or booster and / or downlink buffering in the macro station or booster, depending on capabilities and which link is lost); 2) transmitting data that can alternatively be transmitted directly to the macro station over a link over LTE (the increased LTE link capacity can be used); and 3) discarding the data to be transmitted on the link (this option is the final solution if buffering is not possible and LTE cannot be used). If there is a parallel LTE link to the macro station, it may be beneficial to alternatively transmit some or all of the data via that LTE link.

[0025] If C- / U-plane separation is used (i.e., if the mmWave booster link only serves the U-plane), longer buffering periods or even dropped data packets may be acceptable, depending on the QoS (Quality of Service) requirements of certain bearers. Low-latency data and / or low-data-rate data can be sent along the path to the macro station using LTE, as it is always used for control information. The decision on what data to send via LTE must be made by any of the affected stations, depending on the QoS of each bearer. If the C-plane is also served by the booster (no separation), there is usually no direct path available to the macro station. However, this path can be established using the RACH (Random Access Channel) procedure. To prevent the RACH from being used too frequently for this purpose, a timer-based approach can ensure that the LTE path is only established if the mmWave booster link is lost for a long enough time, as its loss for a long enough time would indicate a problem with the mmWave link. If the booster itself is performing certain radio resource control support functions beyond simply relaying control data, these functions may have to be (temporarily) taken over by the macro station if the path via the booster is blocked. Thus, switching of such functions or temporary parallel execution of such functions may be required. If there is a parallel LTE link to the booster and the event is not ABL- (i.e. anchor-booster-link available), the bypass method mentioned above can also be applied to this link, replacing the LTE link to the macro station. The data transmitted on LTE to bypass the lost mmWave link may contain signaling indicating the link problem and the (temporary) use of LTE. In the case that no parallel LTE link can be used to reach the macro station, intelligent schemes for buffering and eventually dropping packets, as well as prioritization of packets may have to be applied. In cases where C- / U-plane separation is usually possible (appropriate capabilities of UE, booster and anchor), but not always applied, the decision to apply separation may be influenced by the number or frequency of such mmWave link loss events that occur. If these events are frequent, a parallel LTE-link is beneficial and the C-plane can reliably cover this link. Furthermore, a permanent move of the C-plane from mmWave to LTE or vice versa can be done depending on the occurrence of such loss events.

[0026] In coverage extension type deployments, the same countermeasures as discussed above may apply, with certain exceptions. This is due to the fact that in these types of deployments there may not be an alternative LTE link to the macro station.

[0027] Events ABL+, UBbf+

[0028] In the event that the problem with the mmWave link disappears, data transmission on the mmWave can usually continue and the buffered data can be transmitted first to empty the buffer. Alternatively, the affected station may decide to maintain the mmWave link for a period of time before relying on mmWave for data transmission. For example, if control data is transmitted on LTE after a loss event occurs, this control data may be maintained in LTE for a period longer than the user data, so it is important to ensure that the mmWave link is robust before the C-plane traffic moves back to the mmWave link. If functionality other than relaying is moved from the booster to the macro eNB, it may be moved back after this event either immediately or after a timer expires to prevent too frequent function switching.

[0029] Event UAL-

[0030] If the link between the UE and the macro station is lost while the link with the boosted eNB is still available, all data can be transmitted via the mmWave booster link. In particular, if C- / U-plane separation is applied, control data can be transmitted via the booster, indicating the reason for using an alternative route. Primarily, this event converts a capacity deployment into a coverage deployment due to the (temporary) loss of coverage of the macro cell. A timer-based buffer can also be applied to give the macro cell LTE link a chance to reestablish and prevent switching the transmission path too frequently. Alternatively, instead of a timer-based approach, measurement results from LTE connection reestablishment and / or cell search can be taken into account to evaluate the reestablishment chance at a specified appropriate time.

[0031] Event UAL+

[0032] When the macro cell becomes available again, the measures discussed above for the UAL-event can be resumed. Again, the timer can prevent too frequent path switching. Primarily, this event converts a coverage extension deployment into a capacity improvement deployment, as macro cell coverage is reestablished.

[0033] Event UBL-

[0034] In the event that the UE completely loses the mmWave link to the anchor, reestablishing the link is crucial for efficient data transmission. The booster's parallel LTE link to the macro station can be used similarly to the Ubbf event to trigger corresponding LTE station support functions. The support functions in this case can be triggering beacon transmissions by the mmWave booster and / or exchanging timing information for such beacon transmissions. Data transmission and possible function handover from the booster to the anchor can be handled similarly to events ABL and Ubbf, as data transmission via the mmWave booster link is not possible in all cases.

[0035] EventUBL+

[0036] If the mmWave control link becomes available, information can be transmitted via LTE to trigger support for beamforming establishment during the control phase. Data transmission and function switching are not affected because the control link does not provide data transmission capabilities.

[0037] Example of LTE-assisted network operation

[0038] Figures 5A to 5C FIG2 illustrates an example of LTE assisted operation when a UE 100 in the coverage area of ​​an anchor eNB 300 moves into the coverage area of ​​an enhanced eNB 200. Figure 5A In the UE 100, user and control data are sent only via the anchor eNB 300. The anchor eNB will typically have information about the locations of all enhanced eNBs placed on the macro cell and their coverage areas. When the UE 100 is outside the coverage area of ​​the enhanced eNB 200, the anchor eNB 300 maintains a connection with the UE 100. The anchor eNB also has information about the location and movement of the UE 100. Figure 5B In

[15] , when the anchor eNB 300 detects that the UE 100 is approaching the enhanced cell served by the enhanced eNB 200, it notifies the enhanced eNB 200 of the UE's arrival and transfers the UE's related U-plane data to the enhanced eNB. The anchor eNB can also notify the UE of the location of the enhanced eNB. Figure 5C In the present embodiment, when UE 100 enters the coverage of the boosting cell, it performs beamforming training with boosting eNB 200. After the beamforming training, boosting eNB 200 can schedule time for data exchange between the UE and the boosting eNB. The UE can also maintain a connection with the anchor eNB for C-plane data and delay-sensitive U-plane data.

[0039] Example Embodiments

[0040] In Example 1, a method for operating a user equipment (UE) device includes: operating a wireless transceiver to provide an LTE (Long Term Evolution) interface for communicating with an anchor eNB (Evolved Node B) or an enhanced eNB; operating the wireless transceiver to provide a mmWave (millimeter wave) interface for communicating with the enhanced eNB in ​​a control mode or a beamforming mode for establishing a beamforming link between the UE and the enhanced eNB; sending and receiving control plane data on the LTE interface; sending and receiving user plane data on the mmWave interface according to beamforming; and, when the beamforming link between the UE and the enhanced eNB is lost, sending uplink user plane data and an indication of the lost beamforming link on the LTE interface to trigger one or more support functions through the enhanced eNB or anchor eNB to enable the UE to recover the beamforming link.

[0041] In Example 2, the subject matter of Example 1 can optionally include receiving location information including the booster eNB from the anchor eNB for recovering the beamforming link when the beamforming link is lost and an indication of this is sent over the LTE air interface.

[0042] In Example 3, according to the subject matter of any of the preceding examples, it may optionally include: when the beamforming link is lost but the control mode on the mmWave interface is still available, attempting to recover the beamforming link by communicating with the enhanced eNB on the mmWave interface in the control mode using an omnidirectional antenna.

[0043] In Example 4, according to the subject matter of any of the preceding examples, it may optionally include: if the enhanced eNB handles the secondary control plane function on the mmWave interface in addition to the anchor eNB handling the primary control plane function on the LTE interface, when the beamforming link on the mmWave interface is lost, receiving a handover of the secondary control plane function from the enhanced eNB to the anchor eNB.

[0044] In Example 5, according to the subject matter of any of the preceding examples, it may optionally include: when a handover of the auxiliary control plane function from the enhanced eNB to the anchor eNB has been received due to an interruption of the beamforming link and the beamforming link is subsequently restored, moving the user plane traffic to the mmWave interface before moving the control plane traffic to the mmWave interface.

[0045] In Example 6, the subject matter of any of the preceding examples may optionally include sending and receiving delay-sensitive user plane data over the LTE interface.

[0046] In Example 7, a method for operating a user equipment (UE) device includes: operating a wireless transceiver to provide an LTE (Long Term Evolution) interface for communicating with an anchor eNB (Evolved Node B) or an enhanced eNB; operating the wireless transceiver to provide a mmWave (millimeter wave) interface for communicating with the enhanced eNB in ​​a control mode or a beamforming mode for establishing a beamforming link between the UE and the enhanced eNB; sending and receiving user and control plane data on the mmWave interface in the beamforming mode; and, when the beamforming link between the UE and the enhanced eNB is lost, performing a random access procedure on a random access channel (RACH) of the LTE interface to establish an LTE connection with the anchor eNB or the enhanced eNB and sending uplink user and control plane data and an indication of the lost beamforming link on the LTE interface to trigger one or more support functions through the enhanced eNB or the anchor eNB to enable the UE to recover the beamforming link.

[0047] In Example 8, the subject matter according to Example 7 may optionally include the subject matter according to any one of Examples 2 to 6.

[0048] In Example 9, a non-transitory computer-readable storage medium includes instructions for being executed by one or more processors of a UE to configure the UE to perform the operations of any one of the methods recited in Examples 1 to 8.

[0049] In Example 10, a UE includes: a wireless transceiver for providing an LTE (Long Term Evolution) interface for communicating with an anchor eNB (evolved Node B) or an enhanced eNB; a wireless transceiver for providing a mmWave (millimeter wave) interface for communicating with an enhanced eNB in ​​a control mode or a beamforming mode for establishing a beamforming link between the UE and the enhanced eNB; and a processing circuit for performing any one of the methods described in Examples 1 to 8.

[0050] In Example 11, a method for operating an enhanced eNB (evolved Node B) within a macro cell of an anchor eNB includes: sending user plane data to a UE (user equipment) and receiving user plane data from the UE on mmWave (millimeter wave) in a control mode or a beamforming mode for establishing a beamforming link between the UE and the enhanced eNB; when a beamforming link loss on the mmWave interface is detected, sending an indication of the lost beamforming link to the anchor eNB on a backhaul link, commanding the anchor eNB to contact the UE on an LTE interface using support information for recovering the beamforming link.

[0051] In Example 12, the subject matter of Example 11 may optionally include sending delay-sensitive user plane data to the UE and receiving delay-sensitive user plane data from the UE over the LTE interface.

[0052] In Example 13, the subject matter of any one of Examples 11 to 12 may optionally include moving user plane data communications with the UE to the LTE interface when a beamforming link loss on the mmWave interface is detected.

[0053] In Example 14, the subject matter of any one of Examples 11 to 13 may optionally include sending and receiving control plane data to and from the UE over the mmWave interface.

[0054] In Example 15, the subject matter of any one of Examples 11 to 14 may optionally include moving user plane and control plane communications with the UE to an LTE interface when a beamforming link loss on mmWave is detected.

[0055] In Example 16, the subject matter of any one of Examples 11 to 15 may optionally include: when user and control plane traffic is moved from the mmWave interface to the LTE interface due to loss of the beamforming link and the beamforming link is subsequently restored, moving the user plane traffic back to the mmWave interface before moving the control plane traffic back to the mmWave interface.

[0056] In Example 17, a non-transitory computer-readable storage medium includes instructions for being executed by one or more processors of an eNB to perform operations for configuring the eNB to perform any of the methods recited in Examples 11 to 16.

[0057] In Example 18, an enhanced eNB includes a wireless transceiver, a backhaul transceiver, and a processing circuit to perform any of the methods recited in Examples 11 to 16.

[0058] The description in the above specific embodiments includes reference to the accompanying drawings, which form a part of the specific embodiments. The accompanying drawings illustrate specific embodiments that can be put into practice by way of illustration. These embodiments are also referred to herein as "examples". In addition to those shown or described, such examples can also include various elements. However, examples including the elements shown or described are also contemplated. In addition, for a particular example (or one or more aspects thereof), or for other examples (or one or more aspects thereof) shown or described herein, examples (or one or more aspects thereof) of any combination or permutation of those elements shown or described are also contemplated.

[0059] The publications, patents, and patent documents cited in this document are hereby incorporated by reference in their entirety, as if individually incorporated by reference. In the event of inconsistencies in usage between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) supplements that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0060] In this document, as is common in patent documents, the term "one" is used to include one or more, independent of any other examples or usages of "at least one" or "one or more". In this document, the term "or" is used to refer to non-exclusive or to make "A or B" include "A but not B", "B but not A", and "A and B", unless otherwise indicated. In the appended claims, the terms "including" and "in which" are used as the plain English equivalents of the corresponding terms "comprising" and "wherein". In addition, in the claims below, the terms "including" and "comprising" are open-ended, that is, systems, devices, products, or processes that include elements other than those listed after such terms in the claims are still considered to fall within the scope of this claim. In addition, in the claims below, the terms "first", "second", and "third" etc. are used merely as marks and are not intended to imply the numerical order of their objects.

[0061] The embodiments described above may be implemented in various hardware configurations that may include a processor for executing instructions for performing the described techniques. Such instructions may be contained in a machine-readable medium, such as an appropriate storage medium or memory or other processor-executable medium.

[0062] The embodiments described herein may be implemented in a variety of environments, such as a wireless local area network (WLAN), a third generation partnership project (3GPP) universal terrestrial radio access network (UTRAN), or a portion of a long term evolution (LTE) communication system, although the scope of the present invention is not limited thereto. For more information related to the UTRAN LTE standard, see the third generation partnership project (3GPP) standard for UTRAN-LTE, Release 12, including its variants and evolutions. The example LTE system includes a plurality of mobile stations defined by the LTE specifications as user equipment (UE) and communicating with a base station defined by the LTE specifications as an eNodeB.

[0063] The antennas mentioned here may include one or more directional or omnidirectional antennas, including, for example, dipole antennas, dipole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmitting RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be treated as a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, the antennas may be effectively spaced apart to exploit spatial diversity and to generate different channel characteristics between each antenna and the antenna at the transmitting station. In some MIMO embodiments, the antennas may be spaced apart by 1 / 10 wavelength or more.

[0064] The above description is intended to be illustrative, not restrictive. For example, the examples described above (or one or more aspects thereof) can be used in conjunction with other examples. Other embodiments may be used, such as after reading the above description by a person skilled in the art. The abstract is intended to allow the reader to quickly determine the nature of the technical disclosure. The abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above detailed description, various features may be grouped together to make the disclosure smooth. However, the claims may not give every feature disclosed herein, as the embodiments may be characterized by a subset of those features. Further, the embodiments may include fewer features than those disclosed in the specific examples. Thus, the following claims are hereby incorporated into the detailed description, and the claims themselves constitute separate embodiments. The scope of the embodiments disclosed herein is determined by reference to the appended claims and the full scope of equivalents to which such claims are assigned.

Claims

1. A method for operating a user equipment (UE) device, comprising: Communicate with the anchor base station over the LTE link using the LTE radio access technology RAT on the Long Term Evolution (LTE) interface; communicating with a booster base station using a millimeter wave (mmWave) RAT over a mmWave link, wherein the mmWave link includes beamforming between the booster base station and the UE; sending control plane data over the LTE link using the LTE RAT, wherein control plane functions are performed over the LTE link; sending user plane data over the mmWave link using the mmWave RAT; as well as When the mmWave link between the UE and the enhanced base station fails, an indication of the failure of the mmWave link is sent to the anchor base station on the LTE link to trigger one or more support functions of the anchor base station or the enhanced base station to enable the UE to restore the beamforming of the mmWave link.

2. The method according to claim 1, further comprising: When the mmWave link between the UE and the booster base station fails, uplink user plane data and an indication of the loss of the mmWave link are sent to the anchor base station via the LTE link.

3. The method according to claim 1, further comprising: When the mmWave link fails and the indication of the failure is sent on the LTE link, information for recovering the mmWave link is received from the anchor base station, the information including the location of the booster base station.

4. The method according to claim 1, further comprising: When the mmWave link fails, a random access procedure is performed to establish an LTE connection with the anchor base station only after a specific time delay during which the mmWave link remains failed.

5. The method according to claim 1, further comprising: When user plane traffic and control plane traffic are moved from the mmWave interface to the LTE interface due to loss of the mmWave link and the mmWave link is subsequently recovered, user plane traffic is moved back to the mmWave interface before control plane traffic is moved back to the mmWave interface.

6. A user equipment (UE) device, comprising: a first radio transceiver configured to provide a Long Term Evolution (LTE) interface for communicating with an anchor base station over an LTE link; a second radio transceiver configured to provide a millimeter wave (mmWave) interface for communicating with a booster base station over a mmWave link, wherein the mmWave link includes beamforming between the booster base station and the UE; as well as The processing circuit is configured to: sending control plane data over the LTE link using the LTE RAT, wherein control plane functions are performed over the LTE link; sending user plane data over the mmWave link using the mmWave RAT; as well as When the mmWave link between the UE and the enhanced base station fails, an indication of the failure of the mmWave link is sent to the anchor base station on the LTE link to trigger one or more support functions of the anchor base station or the enhanced base station to enable the UE to restore the beamforming of the mmWave link.

7. The UE according to claim 6, wherein: The processing circuit is further configured to: When the mmWave link between the UE and the booster base station fails, uplink user plane data and an indication of the loss of the mmWave link are sent to the anchor base station over the LTE link.

8. The UE according to claim 6, wherein: The processing circuit is further configured to: When the mmWave link fails and the indication of the failure is sent on the LTE link, information for recovering the mmWave link is received from the anchor base station, the information including the location of the booster base station.

9. The UE according to claim 6, wherein: The processing circuit is further configured to: When the mmWave link fails, a random access procedure is performed to establish an LTE connection with the anchor base station only after a specific time delay during which the mmWave link remains failed.

10. The UE according to claim 6, wherein: The processing circuit is further configured to: When user plane traffic and control plane traffic are moved from the mmWave interface to the LTE interface due to loss of the mmWave link and the mmWave link is subsequently recovered, user plane traffic is moved back to the mmWave interface before control plane traffic is moved back to the mmWave interface.

11. A non-transitory computer-readable storage medium storing instructions for execution by one or more processors of a user equipment (UE) to perform operations to configure the UE to perform the method according to any one of claims 1 to 5.

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