Embodiments of the present invention generally relate to wireless communication techniques including the 3GPP (the 3rd Generation Partnership Project) LTE (Long Term Evolution) technique. More particularly, embodiments of the present invention relate to methods, apparatuses, and computer program products for a path switch in device-to-device (D2D) communication.
Various abbreviations that appear in the specification and/or in the drawing figures are defined as below:
BS Base Station
CN Core Network
DRB Data Radio Bearer
DRSF D2D Registration Server Function
eNB evolved Node B
EPS Enhanced Packet System
GW Gateway
MME Mobility Management Entity
ProSe Proximity Services
P-GW Packet Data Network Gateway
RRC Radio Resource Control
RAN Radio Access Network
SDU Service Data Unit
S-GW Serving Gateway
S-TMSI S-Temporary Mobile Subscriber Identity
UE User Equipment
The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the present invention. Some such contributions of the present invention may be specifically pointed out below, while other such contributions of the present invention will be apparent from their context
Currently, 3GPP TR22.803 V0.5.0 (2012-08), “Technical Specification Group SA, Feasibility Study for Proximity Services (ProSe) (Release 12),” defines a default data path and an optimized data path for ProSe communication (e.g., D2D communication), wherein communication over the default data path involves the data path of backhaul and CN side (e.g., S-GW and P-GW) and a RAN side (e.g., eNB) and communication over the optimized data path offloads the backhaul and CN data and only involves the eNB's air-interface data path to the UE. In other words, the D2D communication over the optimized data path is only limited to the case where a single eNB is controlling the D2D communication between two D2D capable UEs, which means UEs that are served by different eNBs cannot establish the optimized data path but the default data path for the D2D communication.
Different from a Wi-Fi technique which naturally enables ad hoc mode communication, incorporating the D2D capability into cellular-based LTE systems appears to confront more technical challenges. For instance, the optimized data path and default data path modes added to the LTE networks would bring about new issues of how to achieve efficient triggers for mode switching, which is deemed important from both user and operator's perspectives in terms of a better user experience, better network offloading efficiency and service continuity, and of how to manage radio bearers during the D2D communication under the LTE systems.
The following presents a simplified summary of the present invention in order to provide a basic understanding of some aspects of the present invention. It should be noted that this summary is not an extensive overview of the present invention and that it is not intended to identify key/critical elements of the present invention or to delineate the scope of the present invention. Its sole purpose is to present some concepts of the present invention in a simplified form as a prelude to the more detailed description that is presented later.
In order to mitigate or alleviate at least one of the potential problems as discussed before, embodiments of the present invention provide an efficient way of performing data path switching between the default data path and the optimized data path such that the data paths of D2D capable UEs can be flexibly and smoothly switched and radio resources could be efficiently utilized.
One embodiment of the present invention provides a method. The method comprises receiving, from a network element, a path switch command which is generated when a pair of UEs in D2D communication over a default data path is served by the same BS. The method also comprises switching, based at least in part upon the path switch command, a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
Another embodiment of the present invention provides a method. The method comprises generating a path switch command when a pair of UEs in D2D communication over a default data path is served by the same BS. The method further comprises sending to a network element the path switch command for switching a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
One embodiment of the present invention provides an apparatus. The apparatus comprises means for receiving, from a network element, a path switch command which is generated when a pair of UEs in D2D communication over a default data path is served by the same BS. The apparatus also comprises means for switching, based at least in part upon the path switch command, a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
A further embodiment of the present invention provides an apparatus. The apparatus comprises means for generating a path switch command when a pair of UEs in D2D communication over a default data path is served by the same BS. The apparatus also comprises means for sending to a network element the path switch command for switching a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
A further embodiment of the present invention provides an apparatus. The apparatus comprises at least one processor and at least one memory including computer program instructions. The at least one memory and computer program instructions are configured to, with the at least one processor, cause the apparatus at least to receive, from a network element, a path switch command which is generated when a pair of UEs in D2D communication over a default data path is served by the same BS. The at least one memory and computer program instructions are also configured to, with the at least one processor, cause the apparatus at least to switch, based at least in part upon the path switch command, a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
An additional embodiment of the present invention provides an apparatus. The apparatus comprises at least one processor and at least one memory including computer program instructions. The at least one memory and computer program instructions are configured to, with the at least one processor, cause the apparatus at least to generate a path switch command when a pair of UEs in D2D communication over a default data path is served by the same BS. The at least one memory and computer program instructions are also configured to, with the at least one processor, cause the apparatus at least to send to a network element the path switch command for switching a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
One embodiment of the present invention provides a computer program product, comprising at least one computer readable storage medium having a computer readable program code portion stored thereon. The computer readable program code portion comprises program code instructions for receiving, from a network element, a path switch command which is generated when a pair of UEs in D2D communication over a default data path is served by the same BS. The computer readable program code portion also comprises program code instructions for switching, based at least in part upon the path switch command, a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
Another embodiment of the present invention provides a computer program product, comprising at least one computer readable storage medium having a computer readable program code portion stored thereon. The computer readable program code portion comprises program code instructions for generating a path switch command when a pair of UEs in D2D communication over a default data path is served by the same BS. The computer readable program code portion also comprises program code instructions for sending to a network element the path switch command for switching a data path of the pair of UEs in the D2D communication from the default data path to an optimized data path.
With the above embodiments of the present invention, by taking into account the serving BS or its changes for the pair of UEs in the D2D communication, efficient triggers for D2D mode switching to the optimized path can be obtained. Further, by switching the data path of the pair of UEs in the D2D communication from the default data path to the optimized data path, backhaul and CN traffic load for operators can be alleviated. In addition, smooth switching as achieved by the embodiments of the present invention brings no performance degradation to the user experience.
The embodiments of the present invention that are presented in the sense of examples and their advantages are explained in greater detail below with reference to the accompanying drawings, in which:
The exemplary embodiments of the present invention provide methods and apparatuses for switching the data path (mode) of the pair of UEs in the D2D communication between the default data path (mode) and the optimized data path (mode) and additionally configuring corresponding D2D radio bearers in the air interface. In one embodiment, switching the data path from the default data path to the optimized data path is performed on the condition that the pair of the D2D capable UEs is served by the same BS, e.g., the same eNB. In another embodiment, switching the data path from the optimized data path to the default data path relies upon the fact that one of the pair of the D2D capable UEs is about to move outside the cell range of the same BS that has been serving the pair of UEs.
Hereinafter, exemplary of the present invention will be described in detail with reference to the accompanying drawings.
To achieve data path switching as above, the embodiments of the present invention introduce the DRSF server which has been employed in some existing D2D communication solutions and is in charge of registration, authentication, identification of the D2D UEs, and charging for the D2D users. Below are brief discussions about how the DRSF server would assist in the data path switching.
In a scenario in which the UE1 and UE2 are in communication with each other over the default data path and over time, the UE1 may leave the cell range of the eNB1 and enter into the cell range of the eNB2, once a handover procedure, as illustrated by a one-way arrow (1), has been completed between the eNB1 and eNB2, the MME will notify the DRSF server of the UE1's new serving eNB (i.e., eNB2)/cell information. Then, the DRSF server may check potential UE pairing information, which has been collected when the D2D UEs registered with the DRSF server, and may find out this pair of UEs are served by the same eNB/cell (i.e., eNB2). On this basis, the DRSF server may send an indication to the MME to trigger backhaul and CN offloading process and perform mode switching from the ongoing default path mode to the optimized data path mode.
In a scenario in which the data path would be switched from the optimized data path to the default data path, the MME should maintain the D2D bearer related information (e.g., QoS parameters) after the D2D communication has been switched from the default path to the optimized data path. This D2D bearer related information could be obtained by the eNB keeping reporting to the MME in case the D2D bearer setup takes place between D2D pairs without MME involvement. When the condition for maintaining the optimized data path cannot be met any more, for example, due to the situation that the one of the pair of UEs becomes increasingly distant from the same eNB and thus the same eNB is no longer appropriate for serving the UE at issue, the same eNB would inform the MME of this situation during a handover preparation. Having been informed of this situation, the MME may indicate this to the DRSF server and then the DRSF server may send a mode switch command to the MME to resume the EPS bearer path according to previously stored D2D bearer related information. In other words, when the UE1 is about to leave the cell range of the eNB2 and thus the optimized data path may no longer be good enough for the D2D communication, the DRSF server may indicate the MME to trigger the mode switching such that the D2D traffic could be on-loaded back to the backhaul and CN side. After the data path has been switched from the optimized data path to the default data path, the UE1 would be handed over from the eNB2 to the eNB1. In this manner, the mode switching would have been completed prior to the handover, resulting in good service continuity.
Although not shown in
In another embodiment, the method 200 comprises receiving, from the network element, another path switch command which is generated when one of the pair of UEs in the D2D communication over the optimized data path is about to move out of a cell range of the same BS and switching, based at least in part upon the other path switch command, the data path of the pair of UEs in the D2D communication from the optimized data path to the default data path.
In yet another embodiment, the method 200 further comprises sending updated cell information of the one of the pair of UEs in the D2D communication to the network element, wherein the updated cell information is used to determine that the one of the pair of UEs is about to move out of the cell range of the same BS. The updated cell information indicates that the one of the pair of UEs is about to move out of the cell range of the same BS.
Owing to the method 200 and its multiple variants and extensions as discussed in the above embodiments, the data path mode switching between the default data path and the optimized data path can be flexibly and smoothly completed. Meanwhile, good service continuity could also be achieved.
Although not shown in
In an embodiment, the method 300 further comprises generating another path switch command when one of the pair of UEs in the D2D communication over the optimized data path is about to move out of a cell range of the same BS and sending to the network element the other path switch command for switching a data path of the pair of UEs in the D2D communication from the optimized data path to the default data path.
In yet another embodiment, the method 300 further comprises receiving, from the network element, updated cell information of the one of the pair of UEs in the D2D communication, wherein the updated cell information is used to determine that the one of the pair of UEs is about to move out of the cell range of the same BS. The updated cell information may indicate that the one of the pair of UEs is about to move out of the cell range of the same BS.
Similar to the method 200, the method 300 and its multiple variants and extension as described above enable smooth switching between the default data path and the optimized data path and thereby service continuity can be well maintained.
Then, at step S406, due to different serving eNBs, the D2D communication between the UE1 and UE2 commences over the default data path. Suppose that the user of the UE1 keeps moving towards eNB 2 during the D2D communication, and thus at step S408, the UE1 is handed over from the eNB1 to the eNB2, as is depicted in the one-way arrow (1) in
Upon receiving the mode switch command from the DRSF server, the MME will perform, at step S416, backhaul and CN offloading for those D2D services by saving the backhaul and CN paths and only leaving D2D radio bearers in the air interface. From an air interface perspective, these D2D radio bearers have nothing different from the normal EPS radio bearers in terms of radio resources consumption. However, both the UE and eNB should be aware that these are D2D radio bearers instead of EPS radio bearers since the UE should tell how to encapsulate D2D data or EPS data to which radio bearers. Further, the eNB needs to differentiate the D2D radio bearers and the EPS radio bearers because it needs to decide whether to forward this uplink data to S-GW or directly to the other paired UE. To realize such differentiation, the embodiments of the present invention propose explicitly indicating in the DRB configuration whether this radio bearer is for D2D services or EPS services during the DRB setup phase. For example, IEs with extension fields (bolded) for the above differentiation are illustrated as below:
Although not depicted in
Suppose that one of the paired D2D UEs, i.e., UE1, is moving from the eNB2 towards the eNB1 at step S508. After the UE1's mobility triggers measurement reporting to the eNB2, the eNB2 realizes the UE1 has ongoing D2D services and prepares a handover procedure to the eNB 1 via the MME. Upon reception of a handover request from the eNB2, the MME will indicate, at step S510, to the DRSF server that the UE1 is about to move to the eNB1, i.e., leaving the cell range of the eNB2. Then, the DRSF server checks and finds out, at step S512, that the UE1 and UE2 are a pair of D2D UEs to be served by different eNBs based upon the pairing information related to the reported UE2. Upon this finding, the DRSF server sends, at step S514, a mode switch command including but not limited to the identifiers of the UE1 and UE2 to the MME. As per the mode switch command, the MME recovers, at step S516, respective backhaul and core network data paths for UE1 and UE2. In other words, the data path of the UE1 and UE2 is switched from the optimized data path to the default data path. Afterwards, at step S518, the UE1 may be handed over from the eNB2 to the eNB1, as is depicted in a one-way arrow (2) in
The foregoing has discussed the embodiments of the present invention in one possible step order, it should be noted that this order is merely illustrative of the present invention. A person skilled in the art can understand that the embodiments of the present invention can be carried out in any suitable orders.
The MEMs 604 and 607 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one MEM is shown in the MME or the DRSF server, there may be several physically distinct memory units in the MME or DRSF server.
The processors 603 and 606 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, DSPs and processors based on multicore processor architecture, as non limiting examples. Either or both of the MME and the DRSF server may have multiple processors, such as for example an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.
The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding entity described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of a corresponding apparatus described with an embodiment and it may comprise separate means for each separate function, or means may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses), firmware (one or more apparatuses), software (one or more modules or virtual means), or combinations thereof. For a firmware or software, implementation can be through modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in any suitable, processor/computer-readable data storage medium(s) or memory unit(s) or article(s) of manufacture and executed by one or more processors/computers. The data storage medium or the memory unit may be implemented within the processor/computer or external to the processor/computer, in which case it can be communicatively coupled to the processor/computer via various means as is known in the art.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these embodiments of the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the invention are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Filing Document | Filing Date | Country | Kind |
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PCT/CN2012/084414 | 11/9/2012 | WO | 00 |