This disclosure generally relates to wireless communication networks, and more particularly, to a method and apparatus for supporting direct communication path PC5 to Uu in a wireless communication system.
With the rapid rise in demand for communication of large amounts of data to and from mobile communication devices, traditional mobile voice communication networks are evolving into networks that communicate with Internet Protocol (IP) data packets. Such IP data packet communication can provide users of mobile communication devices with voice over IP, multimedia, multicast and on-demand communication services.
An exemplary network structure is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system can provide high data throughput in order to realize the above-noted voice over IP and multimedia services. A new radio technology for the next generation (e.g., 5G) is currently being discussed by the 3GPP standards organization. Accordingly, changes to the current body of 3GPP standard are currently being submitted and considered to evolve and finalize the 3GPP standard.
A method and device are disclosed for supporting a communication path switching from PC5 to Uu. In one embodiment, the method includes a second User Equipment (UE) communicating with a first UE via a PC5 unicast link established between the first UE and the second UE. The method also includes the second UE receiving a path switch request message from the first UE, wherein the path switch request message indicates a path switching to Uu. The method further includes the second UE determining to accept the path switch request message according to at least a Uu signal level. In addition, the method includes the second UE transmitting a path switch accept message to the first UE.
The exemplary wireless communication systems and devices described below employ a wireless communication system, supporting a broadcast service. Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), 3GPP LTE (Long Term Evolution) wireless access, 3GPP LTE-A or LTE-Advanced (Long Term Evolution Advanced), 3GPP2 UMB (Ultra Mobile Broadband), WiMax, 3GPP NR (New Radio), or some other modulation techniques.
In particular, the exemplary wireless communication systems and devices described below may be designed to support one or more standards such as the standard offered by a consortium named “3rd Generation Partnership Project” referred to herein as 3GPP, including: TR 23.700-33 V0.2.0, “Study on system enhancement for Proximity based services (ProSe) in the 5G System (5GS); Stage 2 (Release 18)”; and 3GPP TS 23.287 V17.1.0, “Architecture enhancements for 5G System (5GS) to support Vehicle-to-Everything (V2X) services (Release 17)”. The standards and documents listed above are hereby expressly incorporated by reference in their entirety.
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 network. In the embodiment, antenna groups each are designed to communicate to access terminals in a sector of the areas covered by access network 100.
In communication over forward links 120 and 126, the transmitting antennas of access network 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 network using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access network transmitting through a single antenna to all its access terminals.
An access network (AN) may be a fixed station or base station used for communicating with the terminals and may also be referred to as an access point, a Node B, a base station, an enhanced base station, an evolved Node B (eNB), a network node, a network, or some other terminology. An access terminal (AT) may also be called user equipment (UE), a wireless communication device, terminal, access terminal or some other terminology.
In one embodiment, each data stream is 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, QPSK, 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.
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 embodiments, 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 are received by NR antennas 252a through 252r and the received signal from each antenna 252 is provided to a respective receiver (RCVR) 254a through 254r. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes 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 is 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 (discussed below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.
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 then processes the extracted message.
Turning to
3GPP TR 23.700-33 is a technical report for study on system enhancement for Proximity based Services (ProSe) in the 5G System (5GS). Key issue #3 in the technical report (provided in 3GPP TR 23.700-33 V0.2.0) and related solutions for the issue are provided below:
5.3 Key Issue #3: Support direct communication path switching between PC5 and Uu (i.e. non-relay case)
5.3.1 General Description
As illustrated in
When switching the path between the direct communication path over PC5 reference point and the direct communication path over Uu reference point, the ProSe service disruption to the UE should be minimized.
This key issue addresses the following:
6.16 Solution #16: Provisioning policy based direct communication path switching between PC5 and Uu reference points
6.16.1 Description
This solution resolves Key Issue #3 “Support direct communication path switching between PC5 and Uu (i.e. non-relay case)” and Key Issue #6 “Support of PC5 Service Authorization and Policy/Parameter Provisioning”.
The “direct communication path switching between direct PC5 and direct Uu reference points” refers to the procedure on how a UE switches the direct communication paths between PC5 reference point and Uu reference point when it is communicating with another UE. The direct communication path over direct PC5 reference point means that the communication with another UE is performed by using 5G ProSe Direct Communication only. The direct communication path over Uu reference point means that the communication with another UE is performed via the network (i.e. non-relay case) and the communication via 5G ProSe UE-to-Network Relay (Layer-2 or Layer-3) is not considered.
Path switching policy is provided to the UE to indicate which path(s) is allowed for all or specific ProSe services (i.e. direct PC5 allowed, direct Uu allowed or no allowed indicated). The path switching policy is defined as the mapping of ProSe services (i.e. ProSe identifiers) to path allowed (i.e. direct PC5 allowed, direct Uu allowed, or no allowed) and the path switching policy can be a one mapping for all ProSe services (i.e. same path allowed for all ProSe services). The path switching policy can be (pre-) configured in the UE or provided by the PCF. The ProSe Application Server may provide a path allowed indication for ProSe Services to UDR and this may be used by PCF for path switching policy generation and update.
The UE may use the pre-configured/provisioned path switching policy to switching all or specific ProSe services to the appropriate communication path. The “Procedures for Service Authorization and Provisioning to UE” as defined in TS 23.304 [3] is reused for provisioning path switching policy to the UE.
The UE evaluates the path switching policy and switches the communication path as below:
Based on the path switching policy, a UE may establish a PDU session or a PC5 connection in the target path and switch the traffic from the source path to the target path. The service continuity during path switching can be achieved by the application layer mechanism.
6.16.2 Procedures
6.17 Solution #17: Path Switching from PC5 Path to Uu Path
6.17.1 Description
This solution resolves Key Issue #3 for direct communication path switching from PC5 path to Uu path.
This solution uses the make-before-break mechanism to reduce interruption when path switch from PC5 to Uu. The two UEs perform the Uu path preparation procedure for the switched service, and then may release the PC5 connection. During the Uu path preparation procedure phase, the two UEs may negotiate, using the ProSe layer, the Uu QoS based on PC5 QoS via the PC5 connection in order to ensure consistent service experience, and optionally share the IP address used for the Uu path to each other to achieve the switch of service transmission.
6.17.2 Procedures
6.18 Solution #18: UE Negotiation-Based Path Switching from PC5 to Uu
6.18.1 Description
This is a solution related to the Key Issue #3 Support direct communication path switching between PC5 and Uu reference points.
This solution provides a UE Negotiation-Based mechanism for the direct communication path switching between PC5 to Uu reference points. Before performing the path switch, 2 UEs having PC5 connection negotiate the triggers of path switching and what service or QoS flows need to be switched. Once the negotiated triggers are satisfied, the 2 UEs perform the path switching between PC5 to Uu directly. To reduce the service interruption, the principle of “make before break” may be adopted, the 2 UEs may perform corresponding Uu session setup/activation in advance after the UE Negotiation-Based mechanism over PC5 for the path switching from PC5 to Uu interface. For the path switching from the Uu to PC5 interface, it requires that the 2 UEs establish the PC5 link firstly, then negotiate the ProSe services to be switched over the established PC5 link. After that, the 2 UEs perform the path switching based on the negotiated result.
During the negotiation procedure, the 2 UEs may negotiate:
Due to UE mobility or its own conditions (e.g. under congestion control, mobility restriction), the UE can not perform the path switch, then the UE may notify the peer UE of deactivating the negotiated triggers or UE ProSe policy of path switching to avoid the peer UE performing path switch solely.
6.18.2 Procedures for Path Switching from PC5 to Uu with Negotiation
UE #1 and UE #2 may update the negotiated triggers after the negation procedure.
3GPP TS 23.287 specifies Layer-2 link establishment over PC5 reference point as follows:
6.3.3.1 Layer-2 link establishment over PC5 reference point
To perform unicast mode of V2X communication over PC5 reference point, the UE is configured with the related information as described in clause 5.1.2.1.
Key issue #3 in 3GPP TR 23.700-33 describes support of direct communication path switching between PC5 and Uu (i.e. non-relay case). The direct communication path over PC5 reference point means that the communication (associated with a service) between two concerned UEs is performed via a PC5 unicast link (or a Layer-2 link) established between these two UEs. The direct communication path over Uu reference point means that the communication between two concerned UEs is performed via a data network. Basically, each UE establishes a Protocol Data Unit (PDU) session (associated with the service) with the data network and then communicates with each other via the established PDU sessions.
According to Step 3 of
After UE1 determines to switch the communication path from PC5 to Uu, UE1 may transmit a path switch request to UE2. To ensure the communication path switch from PC5 to Uu can be successful, there is also a need for UE2 to check whether its Uu signal level is good enough to support the ongoing service before accepting the path switch request. For example, the Uu signal level is higher than or equal to a third threshold (associated with the ongoing service), the Uu signal level is higher than a PC5 signal level, or the Uu signal level is higher than the PC5 signal level plus a fourth threshold. Otherwise, UE2 should reject the path switch request. In one embodiment, the third threshold may be equal to the second threshold. The path switch request may be a PC5-S message and another PC5-S message may be used to reply a path switch accept.
UE2 may further check other conditions to accept the path switch request, e.g. the path switch (for a service) to Uu is allowed (according to the path switch policy) and/or UE2 is camping to a suitable cell (for UE in RRC_IDLE) or connecting to a serving cell (for UE in RRC_CONNECETD). In one embodiment, the path switch request message may include information indicating a set of services to be switched to the Uu path. And, the path switch accept message may include information indicating another set of services to be switched to the Uu path. The set of services included in the path switch accept message may be a subset of the set of services included in the path switch request message. Each set of services may include at least one service. The set of services included in the path switch accept message may be allowed to be switched to the Uu path according to the path switch policy. In one embodiment, UE2 in RRC_IDLE may need to establish a RRC connection with a gNB before replying a path switch accept to UE 1.
After the path switch request message is accepted, each UE could start Uu path preparation. For example, each UE could establish a RRC connection (if not yet established) with its serving gNB and establish a PDU session for the concerned service with the data network. DRBs to support the PDU session should also be established. After PDU sessions and related DRBs are established, both UEs may then communicate with each other via the established PDU sessions or the DRBs. The PC5 unicast link and/or all sidelink (or PC5) radio resources may then be released.
In one embodiment, the PC5 signal level may refer to the strength of a reference signal/discovery signal received from UE1 or UE2. And, the Uu signal level may refer to the strength of a reference signal received from its camping/serving cell.
In one embodiment, the second UE could determine to accept the path switch request message if the Uu signal level is higher than or equal to a first threshold, if the Uu signal level is higher than a PC5 signal level, or if the Uu signal level is higher than the PC5 signal level plus a second threshold. The PC5 signal level may refer to a strength of a reference signal or a discovery signal received from the second UE.
In one embodiment, the second UE could determine to accept the path switching to Uu if the path switch to Uu is allowed. The second UE could determine to accept the path switching to Uu if the second UE is camping to a suitable cell or connecting to a serving cell.
In one embodiment, the Uu signal level may refer to a strength of a reference signal received from a camping/serving cell of the second UE. The path switch request message may include information indicating a first set of services to be switched to Uu. The path switch accept message may also include information indicating a second set of services to be switched to Uu. The second set of services could be a subset of the first set of services. The second UE could determine to accept the path switching to Uu if at least a service in the first set of services is allowed to be switched to Uu.
Referring back to
Various aspects of the disclosure have been described above. It should be apparent that the teachings herein could be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein could be implemented independently of any other aspects and that two or more of these aspects could be combined in various ways. For example, an apparatus could be implemented or a method could be practiced using any number of the aspects set forth herein. In addition, such an apparatus could be implemented or such a method could be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. As an example of some of the above concepts, in some aspects concurrent channels could be established based on pulse repetition frequencies. In some aspects concurrent channels could be established based on pulse position or offsets. In some aspects concurrent channels could be established based on time hopping sequences. In some aspects concurrent channels could be established based on pulse repetition frequencies, pulse positions or offsets, and time hopping sequences.
Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those of skill would further appreciate that the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two, which may be designed using source coding or some other technique), various forms of program or design code incorporating instructions (which may be referred to herein, for convenience, as “software” or a “software module”), or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
In addition, the various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit (“IC”), an access terminal, or an access point. The IC may comprise a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute codes or instructions that reside within the IC, outside of the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional 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.
It is understood that any specific order or hierarchy of steps in any disclosed process is an example of a sample approach. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module (e.g., including executable instructions and related data) and other data may reside in a data memory such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. A sample storage medium may be coupled to a machine such as, for example, a computer/processor (which may be referred to herein, for convenience, as a “processor”) such the processor can read information (e.g., code) from and write information to the storage medium. A sample storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in user equipment. In the alternative, the processor and the storage medium may reside as discrete components in user equipment. Moreover, in some aspects any suitable computer-program product may comprise a computer-readable medium comprising codes relating to one or more of the aspects of the disclosure. In some aspects a computer program product may comprise packaging materials.
While the invention has been described in connection with various aspects, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.
The present Application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/334,400 filed on Apr. 25, 2022, the entire disclosure of which is incorporated herein in its entirety by reference.
Number | Date | Country | |
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63334400 | Apr 2022 | US |