Offload communication functions from slave user devices to master user devices

Abstract

In one aspect, both a slave UE and a master UE establish attachment to a core network of a cellular communication system. The slave UE obtains security credentials configured to encrypt and decrypt traffic between the slave UE and the core network. A D2D connection (e.g., tethering) is established between the slave UE and the master UE. One or more communication functions are offloaded from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining attachment of the slave UE to the core network. Application layer data is relayed to / from the slave UE over the D2D connection. In one aspect, the slave UE or the master UE may perform encryption and decryption of control plane signaling using the security credentials of the slave UE.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefits of the following applications: U.S. Provisional Application No. 62 / 909,535, filed on October 2, 2019, entitled “OFFLOADING COMMUNICATION FUNCTIONS FROM A SLAVE USER EQUIPMENT TO A MASTERUSER EQUIPMENT,” and U.S. Non-Provisional Application No. 17 / 060,973, filed on October 1, 2020, entitled “OFFLOADING COMMUNICATION FUNCTIONS FROM ASLAVE USER EQUIPMENT TO AMASTERUSER EQUIPMENT,” both of which are assigned to the assignee of this application and are hereby expressly incorporated herein by reference in their entirety. Technical Field

[0003]

[0011] Generally speaking, aspects of the present disclosure relate to wireless communications and techniques and apparatus for offloading one or more communication functions from a slave user equipment (UE) to a master UE. Background Art

[0004] Wireless communication systems have evolved over several generations, including first generation analog wireless telephone service (1G), second generation (2G) digital wireless telephone service (including temporary 2.5G networks), third generation (3G) high speed data, wireless service with Internet capabilities, and fourth generation (4G) services (e.g., Long Term Evolution (LTE), WiMax). There are many different types of wireless communication systems in use today, including cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Global System for Mobile Access (GSM) variants of TDMA, and the like.

[0005] The fifth generation (5G) mobile standard requires higher data transmission speeds, a greater number of connections and better coverage, among other improvements. According to the Next Generation Mobile Network Alliance, the 5G standard (also referred to as "new radio" or "NR") is designed to provide data rates of tens of megabits per second to each of tens of thousands of users, with a data rate of 1 gigabit per second provided to dozens of employees on an office floor. In order to support large sensor deployments, hundreds of thousands of simultaneous connections should be supported. Therefore, the spectrum efficiency of 5G mobile communications should be significantly enhanced compared to the current 4G / LTE standards. In addition, signaling efficiency should be enhanced and latency should be significantly reduced compared to current standards. Summary of the invention

[0006] A simplified summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be presented later.

[0007] In some designs, a user equipment (UE) (e.g., a NR light or RedCap UE (such as a wearable device), or any type of UE with low available processing capacity and / or low battery condition) can become tethered to another UE (e.g., a smartphone). In such an arrangement, the tethered UE can be characterized as a slave UE, and the UE to which the slave UE is tethered can be characterized as a master UE. This tethering can be achieved via a device-to-device (D2D) connection (which can alternatively be referred to as a personal area network (PAN) connection (e.g., via Bluetooth, LTE-D, WiFi Direct, etc.)). Many legacy slave UEs need to be tethered to a master UE in order to obtain cellular network connectivity via the master UE. However, it is now becoming increasingly common for slave UEs to be equipped with their own cellular modems to allow cellular connectivity even when the slave UE is not tethered (e.g., a user can leave his / her smartphone at home while running with a smart watch that provides cellular connectivity (even if not tethered to a smartphone, etc.)). Thus, the slave UE can connect to an application server to obtain various services in various ways.

[0008] Cellular communications typically consume more power than tethered D2D communications given the higher distances involved. Hence, offloading some cellular-related communication functions from the slave UE to the master UE when tethered may result in power savings at the slave UE.

[0009] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a slave UE. The slave UE establishes an attachment to a core network of a cellular communication system and obtains a set of security credentials, the set of security credentials being configured to encrypt and decrypt services between the slave UE and the core network. The slave UE establishes a D2D connection with a master UE that is also attached to the core network. The slave UE offloads one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network, the one or more offloaded communication functions including the transmission of control plane signaling associated with the security credential set of the slave UE. The slave UE exchanges application layer data relayed by the master UE on the D2D connection and directed to an application server or received from the application server.

[0010] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a master UE. The master UE establishes an attachment to a core network of a cellular communication system. The master UE establishes a D2D connection with a slave UE that is also attached to the core network. The master UE offloads one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network. The master UE performs one or more offloaded communication functions on behalf of the slave UE, the one or more offloaded communication functions including the transmission of control plane signaling associated with a security credential set assigned to the slave UE. The master UE relays application layer data between an application server and the slave UE via the D2D connection.

[0011] In general, various aspects include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, cIoT user equipment, base stations, wireless communication devices and / or processing systems as fully described with reference to the accompanying drawings, specifications and appendices and as illustrated by the accompanying drawings, specifications and appendices.

[0012] The foregoing has been fairly broadly summarized according to the features and technical advantages of the examples of the present disclosure, so that the specific embodiments below can be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples can be easily utilized as the basis for modifying or designing other structures for the same purpose of performing the present disclosure. Such equivalent constructions do not deviate from the scope of protection of the attached claims. When considered in conjunction with the accompanying drawings, the characteristics of the concepts disclosed herein (both their organization and method of operation) and the associated advantages will be better understood according to the description below. Each of the figures in the accompanying drawings is provided for the purpose of illustration and description, and is not defined as a limitation to the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0014] Figure 2 is a diagram showing an example of communication between a base station and a UE in a wireless communication network.

[0015] Figure 3 A communication system according to an embodiment of the present disclosure is shown.

[0016] Figure 4 An exemplary process for wireless communication according to an aspect of the present disclosure is shown.

[0017] Figure 5 An exemplary process for wireless communication according to another aspect of the present disclosure is shown.

[0018] Figure 6 An embodiment according to the present disclosure is shown. Figure 3 Example communication paths (e.g., control plane signaling paths and user plane (or data plane) traffic paths) of a communication system.

[0019] Figure 7 An embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation of a process.

[0020] Figure 8 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation of a process.

[0021] Fig. 9 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation of a process.

[0022] Fig.10 An embodiment according to the present disclosure is shown. Figure 3Example communication paths (e.g., control plane signaling paths and user plane (or data plane) traffic paths) of a communication system.

[0023] Fig.11 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation of a process.

[0024] Fig.12 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation of a process.

[0025] Fig.13 is a conceptual data flow diagram illustrating the data flow between different units / components according to an aspect of the present disclosure.

[0026] Fig.14 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to an aspect of the present disclosure.

[0027] Fig.15 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to another aspect of the present disclosure. DETAILED DESCRIPTION

[0028] The specific embodiments described below in conjunction with the accompanying drawings are intended to be descriptions of various configurations and are not intended to represent configurations in which the concepts described herein may be practiced. For the purpose of providing a comprehensive understanding of each concept, the specific embodiments include specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid blurring such concepts.

[0029] Several aspects of telecommunication systems will now be presented with reference to various devices and methods. These devices and methods will be described in the following detailed description and illustrated in the accompanying drawings by means of various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0030] For example, an element, or any part of an element, or any combination of elements can be implemented using a "processing system" including one or more processors. Examples of processors include: microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other appropriate hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other initial terms, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0031] Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or encoded on a computer-readable medium as one or more instructions or codes. Computer-readable media include computer storage media. Storage media may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), compact disc ROM (CD-ROM) or other optical disc storage, disk storage or other magnetic storage device, a combination of the aforementioned types of computer-readable media, or any other medium that may be used to store computer executable code that can be accessed by a computer in the form of an instruction or data structure.

[0032] It should be noted that although various aspects may be described using terms commonly associated with 3G and / or 4G wireless technologies, various aspects of the present disclosure may be applied to communication systems based on other generations, such as 5G and beyond (including 5G technologies).

[0033] Figure 11 is a schematic diagram showing a wireless network 100 in which various aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network (such as a 5G network). The wireless network 100 may include a plurality of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with a user equipment (UE) and may also be referred to as a base station, 5G BS, Node B, gNB, 5G NB, access point, transmit receive point (TRP), etc. Each BS may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to a coverage area of ​​a BS and / or a BS subsystem serving the coverage area, depending on the context in which the term is used.

[0034] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1 In the example shown in , BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102c. A BS may support one or more (e.g., three) cells. The terms "eNB", "base station", "5G BS", "gNB", "TRP", "AP", "Node B", "5G NB", and "cell" may be used interchangeably herein.

[0035] In some examples, the cells may not necessarily be stationary, and the geographic area of ​​the cells may move depending on the location of the mobile BS. In some examples, the BSs may be interconnected with each other and / or with one or more other BSs or network nodes (not shown) in the wireless network 100 via various types of backhaul interfaces (such as direct physical connections using any appropriate transport network, virtual networks, etc.).

[0036] The wireless network 100 may also include a relay station. A relay station is an entity that can receive data transmissions from an upstream station (e.g., a BS or a UE) and send data transmissions to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that is capable of relaying transmissions for other UEs. Figure 1 In the example shown in , a relay station 110d may communicate with a macro BS 110a and a UE 120d to facilitate communication between the BS 110a and the UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, or the like.

[0037] The wireless network 100 may be a heterogeneous network including different types of BSs (e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different effects on interference in the wireless network 100. For example, a macro BS may have a higher transmit power level (e.g., 5 to 40 watts), and a pico BS, a femto BS, and a relay BS may have a lower transmit power level (e.g., 0.1 to 2 watts).

[0038] The network controller 130 may be coupled to a set of BSs and may provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with each other directly or indirectly, for example, via a wireless or wired backhaul.

[0039] UE 120 (e.g., 120a, 120b, 120c) can be dispersed throughout the wireless network 100, and each UE can be stationary or mobile. UE can also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet device, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or apparatus, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device or a satellite radio unit), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing device, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium.

[0040] Some UEs may be considered as machine type communication (MTC) or evolved or enhanced machine type communication (eMTC) UEs. "MTC" may refer to MTC or eMTC. MTC UEs include, for example, robots, drones, remote devices (e.g., sensors, meters, monitors, location tags, etc.), which may communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity to a network (e.g., a wide area network such as the Internet or a cellular network) or connectivity to a network, for example, via a wired or wireless communication link. Some UEs may be considered as Internet of Things (IoT) devices, and / or may be implemented as NB-IoT (narrowband Internet of Things) devices. IoT UEs, eMTC UEs, coverage enhancement (CE) mode UEs, bandwidth limited (BL) UEs, and other types of UEs using reduced power consumption relative to a baseline UE may be referred to herein as cellular IoT (cIoT) UEs. Some UEs may be considered as customer premises equipment (CPE). UE 120 may be included inside a housing that houses components (e.g., processor components, memory components, etc.) of UE 120.

[0041] Typically, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a specific RAT and can operate on one or more frequencies. RAT can also be referred to as radio technology, air interface, etc. Frequency can also be referred to as carrier, frequency channel, etc. Each frequency can support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, a 5G RAT network can be deployed.

[0042] In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication between some or all devices and apparatuses within a service area or cell of the scheduling entity. Within the present disclosure, as further discussed below, a scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. Access to the air interface may be controlled, for example, using a unified access control (UAC) system, in which a UE is associated with an access identity (e.g., an access category, etc.), which may be intended to ensure that certain high priority UEs (e.g., emergency response UEs, mission-critical UEs, etc.) can access the air interface even under congested conditions. Messages such as paging messages or direct indication information may be used to provide the cIoT UE with a battery charge of the cIoT UE for UAC parameters.

[0043] The base station is not the only entity that can act as a scheduling entity. That is, in some examples, the UE can act as a scheduling entity that schedules resources for one or more subordinate entities (e.g., one or more other UEs). In this example, the UE is acting as a scheduling entity, and other UEs wirelessly communicate using resources scheduled by the UE. The UE can act as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In the mesh network example, in addition to communicating with the scheduling entity, the UEs can also optionally communicate directly with each other.

[0044] Thus, in a wireless communication network having scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more slave entities may communicate using the scheduled resources.

[0045] As pointed out above, Figure 1 This is provided only as an example. Other examples may differ from those described above. Figure 1 An example of description.

[0046] Figure 2 Base station 110 and UE 120 (which may be Figure 1 2. Block diagram 200 of a design of a base station 110 and a UE 120 in FIG. 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general, T≥1 and R≥1.

[0047] At the base station 110, the transmit processor 220 may receive data for one or more UEs from the data source 212, select a modulation and coding scheme (MCS) for each UE based at least in part on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for the UE based at least in part on the MCS selected for each UE, and provide data symbols for all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MOD) 232a to 232t. Each modulator 232 may process a corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a to 232t may be transmitted via T antennas 234a to 234t, respectively. According to various aspects described in more detail below, synchronization signals may be generated using position coding to transmit additional information.

[0048] At UE 120, antennas 252a to 252r may receive downlink signals from base station 110 and / or other base stations, and may provide received signals to demodulators (DEMOD) 254a to 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. A receive (RX) processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. The channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a channel quality indicator (CQI), and the like.

[0049] On the uplink, at the UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 (if applicable), further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the demodulator 232, detected by the MIMO detector 236 (if applicable), and further processed by the receive processor 238 to obtain decoded data and control information transmitted by the UE 120. The receive processor 238 may provide decoded data to a data sink 239 and decoded control information to a controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0050] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other component of the UE 120 may perform one or more techniques associated with UAC parameter updates, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other component may perform or direct e.g. Figure 5 The operations of process 500 and / or other processes as described herein. Memories 242 and 282 may store data and program codes for BS 110 and UE 120, respectively. Scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0051] As pointed out above, Figure 2 This is provided only as an example. Other examples may differ from those described above. Figure 2 An example of description.

[0052] As mentioned above, various device types can be characterized as UEs. Starting from 3GPP Release 17, multiple UE types in these UE types are assigned new UE categories, which are denoted as "NR Light" UEs or Reduced Capability ("RedCap") UEs. Examples of UE types that fall into the RedCap category include wearable devices (e.g., smart watches, etc.), industrial sensors, cameras (e.g., surveillance cameras, etc.), etc. Typically, UE types grouped under the RedCap category are associated with lower communication capacities. For example, relative to a "normal" UE (e.g., a UE that is not classified as RedCap), a RedCap UE may be limited in terms of the maximum bandwidth for transmission and / or reception (e.g., 5MHz, 10MHz, 20MHz, etc.), the maximum transmission power (e.g., 20dBm, 14dBm, etc.), the number of receiving antennas (e.g., 1 receiving antenna, 2 receiving antennas, etc.). Some RedCap UEs may also be sensitive in terms of power consumption (e.g., requiring a long battery life, such as several years), and may be highly mobile. Furthermore, in some designs, it is often desirable for RedCap UEs to coexist with UEs implementing protocols such as eMBB, URLLC, LTE NB-IoT / MTC, etc. In one specific example, Industrial IoT (I-IOT) wireless sensors may be associated with intensive uplink traffic, moderate reliability and latency (e.g., non-URLLC), small packet sizes with relatively long TX intervals (e.g., low data rates), and high capacity (e.g., up to 1 UE per square meter).

[0053] In some designs, a UE (e.g., a NR Lightweight or RedCap UE, such as a wearable device) can be tethered to another UE (e.g., a smartphone). In such an arrangement, the tethered UE can be characterized as a slave UE, and the UE to which the slave UE is tethered can be characterized as a master UE. Such tethering can be achieved via a device-to-device (D2D) connection, which can alternatively be referred to as a personal area network (PAN) connection (e.g., via Bluetooth, LTE-D, WiFi Direct, etc.). Many older slave UEs need to be tethered to a master UE in order to obtain cellular network connectivity via the master UE. However, it is now becoming increasingly common for slave UEs to be equipped with their own cellular modems to allow cellular connectivity even when the slave UE is not tethered (e.g., a user can leave his / her smartphone at home while running with a smartwatch that provides cellular connectivity (even when not tethered to a smartphone, etc.)

[0054] Therefore, the slave UE can be connected to the application server to obtain various services in various ways. Some slave UEs can act as (mostly) independent devices that use their own respective cellular modems to obtain cellular connectivity (even when tethered). In such a design, the application server is actually the main device, and the slave UE and the master UE can exchange data with the application server separately. In such a design, the work of the application server is to ensure that the state and data on the slave UE and the master UE are consistent and synchronized. In this case, the tethering between the slave UE and its master UE is implemented at the transport layer. In other designs, the slave UE can be a permanent attachment to the master UE. In this case, all data exchanged by the slave UE are facilitated via the master UE. The master UE controls and can filter the data between the slave UE and the application server. In such a design, the slave UE may not be visible to the application server.

[0055] Figure 3 A communication system 300 according to an embodiment of the present disclosure is shown. Figure 3 , the slave UE 302 is configured to be tethered to the master UE 304. However, at any particular point in time, the slave UE 302 can be in a tethered state or an untethered state. The slave UE 302 and the master UE 304 are each equipped with components that allow a cellular connection to a radio access network (RAN) 306. In one example, the RAN 306 may include Figure 1-Figure 2 Any one of the base stations 110, and each of the slave UE 302 and the master UE may correspond to Figure 1-Figure 2 120. In some designs, the slave UE 302 may correspond to an NR light or RedCap UE, such as a wearable device. However, the slave UE 302 may more generally correspond to any type of UE, as the technical advantages associated with various aspects of the present disclosure (e.g., reduced power consumption, freeing up processing capacity, etc.) are not limited to applications with respect to NR light or RedCap UEs. The RAN 306 is communicatively coupled to the core network 308 via a backhaul connection. The RAN 306 and the core network 308 may be collectively referred to as a cellular communication system. The core network 308 is communicatively coupled to an application server 310 (e.g., via a communication interface such as an Internet connection). The application server 310 may provide any of a variety of services (e.g., video streaming, audio streaming, social networking services, etc.).

[0056] In order to maintain the attachment between the slave UE 302 and the core network 308, certain communication functions need to be performed by the slave UE 302. Such communication functions include the generation, processing, encryption and decryption of control plane signaling, or the generation, processing and transmission of data plane signaling (e.g., application layer traffic that may flow between the slave UE 302 and the application server 310) using a set of security credentials assigned to the slave UE 302 in association with the attachment.

[0057] Embodiments of the present disclosure relate to offloading at least some communication functions for maintaining attachment of a slave UE to a core network from a slave UE to a master UE. In some designs, the offloading occurs in response to establishing a D2D connection (i.e., tethering) between the slave UE and the master UE. Offloading can bring various technical advantages, such as reduced power consumption and system resource utilization. In some designs, the slave UE can correspond to an NR light or RedCap UE, while in other designs, the slave UE can correspond to any type of UE (e.g., any UE for which it is desired to reduce power consumption and / or reduce processing load, such as a UE with higher processing power but experiencing a low battery condition, or a UE with a high processing load that attempts to slightly reduce the processing load, etc.).

[0058] Figure 4 An exemplary process 400 of wireless communications is shown in accordance with an aspect of the present disclosure. Figure 4 Process 400 is performed by slave UE 302, which may correspond to an example implementation of UE 120.

[0059] At 402, an attachment to a core network of a cellular communication system is established from the UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264). In an example, the attachment of 402 may be facilitated via a message exchange facilitated by the RAN 306. The attachment of 402 may be achieved via a cellular communication interface (e.g., a cellular modem, etc.) from the UE 302.

[0060] At 404, a set of security credentials is obtained from the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264). In an example, the set of security credentials may be obtained as a result of an attach procedure of 402. For example, the attach of 402 may include a security exchange procedure (e.g., an attach request, an authentication request, an authentication response, a security command request, a security command completion, etc.). After the security exchange procedure is completed, the slave UE 302 has the necessary security credentials for encrypting and decrypting control plane signals exchanged between the slave UE and the core network 308. For example, the control plane signaling may include non-access stratum (NAS) / access stratum (AS) signaling.

[0061] At 406, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) establishes a device-to-device (D2D) connection (e.g., PAN link) with the master UE 304 that is also attached to the core network 308. In some designs, the D2D connection is established via a communication protocol (e.g., Bluetooth, LTE-D, WiFi Direct, etc.) that uses less power than a cellular communication protocol used for direct wireless communication between the slave UE 302 or master UE 304 and the RAN 306.

[0062] At 408, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally transmits the set of security credentials obtained at 404 to the master UE 304. In an example, the optional transmission of 408 may occur over the D2D connection established at 406. In an example, the optional transmission of 408 may be implemented to facilitate the master UE 304 to perform generation, processing, encryption, and decryption of control plane signaling using the set of security credentials of the slave UE 302 without the participation of the slave UE 302. In an alternative example, the optional transmission of 408 may be omitted. In this case, the slave UE 302 may be responsible for performing generation, processing, encryption, and decryption of control plane signaling using the set of security credentials of the slave UE 302 even when tethered to the master UE 304.

[0063] At 410, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) offloads one or more communication functions from the slave UE 302 to the master UE 304, the one or more communication functions including at least one communication function with the core network 308 for maintaining attachment of the slave UE 302 to the core network 308, the one or more offloaded communication functions including transmission of control plane signaling associated with a set of security credentials of the slave UE (e.g., to maintain attachment of the slave UE 302 to the core network). In some designs, the one or more offloaded communication functions may also include functions that are not explicitly required for maintaining attachment of the slave UE 302 to the core network 308. As mentioned above with respect to 408, in addition to the transmission of control plane signaling associated with the security credential set of the slave UE, the slave UE 302 may also (optionally) offload the generation, processing, encryption, and decryption of control plane signaling using the security credential set of the slave UE 302 without the participation of the slave UE 302. The offloading of 410 may be facilitated via a messaging exchange (e.g., setup / registration information) between the slave UE 302 and the master UE 304 over the D2D connection. In some designs, the offloaded communication functions may include paging monitoring functions and transmission of mobile-initiated service requests. In some designs, when the slave UE 302 is actively transmitting data traffic with a cellular network, the offloaded communication functions may include relay functions, whereby the master UE 304 exchanges application layer data traffic with the access network 306 on the physical layer on behalf of the slave UE 302, and then relays the application layer data traffic with the slave UE 302 over the D2D connection. In some designs, the offloaded communication functions may include radio resource management (RRM) and mobility management.

[0064] At 412, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) exchanges application layer data relayed by the master UE 304 on the D2D connection and received for or from the application server 310. The application layer data (or data plane traffic) may include mobile originated (MO) data, mobile terminated (MT) data, or a combination thereof. In some designs, the application layer data may be exchanged at 412, wherein the tethering between the slave UE 302 and the master UE 304 remains transparent to the application server 310.

[0065] At 414, after the offloading of 410, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulator 254a ... 254r, TX processor 264) optionally continues to perform at least one non-offloaded communication function (e.g., including one or more functions required to maintain attachment from the UE to the core network). In some designs, the at least one non-offloaded communication function may include: performing generation, processing, encryption, and decryption of control plane signaling (e.g., NAS / AS signaling, such as control plane registration messages, TAU messages, etc.) using the security credential set of the slave UE 302 (e.g., if the optional sending of 408 is not performed). In such a case, the control plane signaling is relayed to / from the slave UE 302 via the master UE 304 on the D2D connection. The non-offloaded communication functions may also include generation and processing of data plane traffic. For example, data plane traffic may be relayed to / from the master UE 304 via a D2D connection, which may use less power than a wireless connection to the RAN 306. In some designs, control plane signaling may be relayed to / from the master UE 304 in a similar manner.

[0066] At 416, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258) optionally receives a request to generate a control message (e.g., control plane signaling). The request of 416 may be received over the D2D connection. In an example, the request received at 416 is optional because the generation, processing, encryption, and decryption of the control plane signaling may be offloaded to the master UE 304 instead, in which case the master UE 304 will generate the control message itself without the participation of the slave UE 302. In an example, the control message may correspond to a control plane registration update message or a tracking area update (TAU) message.

[0067] At 418, the slave UE 302 (e.g., the controller / processor 280) optionally generates a control message in response to the request of 416. In an example, the control message is generated (e.g., encrypted) based on the set of security credentials of the slave UE 302 obtained at 404. As mentioned above, the generation of 418 is optional because the generation, processing, encryption, and decryption of the control plane signaling can be offloaded to the master UE 304 instead, in which case the master UE 304 will generate the control message itself without the participation of the slave UE 302.

[0068] At 420, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally sends a control message to the master UE 304. The transmission of 420 may occur over the D2D connection. As mentioned above, the transmission of 420 is optional because the generation, processing, encryption, and decryption of the control plane signaling may be offloaded to the master UE 304 instead, in which case the master UE 304 will generate the control message itself without the participation of the slave UE 302.

[0069] At 422, the slave UE 302 (e.g., the controller / processor 280) optionally determines to resume execution of the communication functions offloaded from 410. In some designs, the optional determination of 422 may occur in response to a link quality associated with the D2D connection falling below a threshold. In some designs, the optional determination of 422 may occur in response to a teardown (e.g., untethering) of the D2D connection.

[0070] At 424, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258) optionally receives information from the master UE 304 over the D2D connection to facilitate resumption of one or more offloaded communication functions. For example, the information received at 424 may include system information, measurements, uplink and downlink timing, etc., so that the slave UE 302 does not need to re-collect such information. In some designs, the slave UE 302 and the master UE 304 may have different supported bandwidths and / or other capabilities (e.g., because the slave UE 302 may be an NR light or RedCap UE, or any type of UE with low available processing capacity and / or low battery condition), which may result in different applicable system parameters or measurements. In such a case, an offset (e.g., configured by the network or defined in the 3GPP specification) may be applied.

[0071] At 426, the slave UE 302 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally sends a message to the core network 308 reporting UE capability information for the slave UE 302. For example, as mentioned above, the slave UE 302 and the master UE 304 may have different capabilities. As part of the offload of 410, the slave UE 426 may receive an indication of the capability information for the master UE 304, and then transmit a message reporting the capability information for the master UE 304 as the capability information for the slave UE 302. Thus, after the offload of 410, the slave UE 302 may benefit from the enhanced capabilities of the master UE 304. In this case, the optional sending of 426 may be performed to degrade cellular performance to a level that can be supported by the slave UE 302 using its own cellular communication hardware (e.g., cellular modem, etc.).

[0072] Figure 5 An exemplary process 500 for wireless communications according to another aspect of the present disclosure is shown. Figure 5 Process 500 is performed by a master UE 304, which may correspond to an example implementation of UE 120.

[0073] At 502, the primary UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) establishes an attachment to the core network of the cellular communication system. In an example, the attachment of 502 may be facilitated via a message exchange facilitated by the RAN 306. The attachment of 502 may be achieved via a cellular communication interface (e.g., a cellular modem, etc.) of the primary UE 304.

[0074] At 504, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) establishes a device-to-device (D2D) connection (e.g., a PAN link) with a slave UE 302 that is also attached to the core network 308. In some designs, the D2D connection is established via a communication protocol (e.g., Bluetooth, LTE-D, WiFi-Direct, etc.) that uses less power than a cellular communication protocol used for direct wireless communication between the slave UE 302 or master UE 304 and the RAN 306.

[0075] At 506, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally receives the obtained set of security credentials assigned to the slave UE 302. In an example, the optional reception of 506 can occur over the D2D connection established at 504. In an example, the optional reception of 506 can be implemented to facilitate the master UE 304 to perform generation, processing, encryption, and decryption of control plane signaling using the security credential set of the slave UE 302 without the participation of the slave UE 302. In an alternative example, the optional reception of 506 can be omitted. In this case, the slave UE 302 can be responsible for performing generation, processing, encryption, and decryption of control plane signaling using the security credential set of the slave UE 302 even when tethered to the master UE 304.

[0076] At 508, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) offloads one or more communication functions from the slave UE 302 to the master UE 304, including at least one communication function with the core network 308 for maintaining the attachment of the slave UE 302 to the core network 308. In some designs, the offloading of 508 may be facilitated via a messaging exchange (e.g., setup / registration information) between the slave UE 302 and the master UE 304 over the D2D connection. In some designs, the offloaded communication functions may include paging monitoring functions and transmission of service requests initiated by the mobile station. In some designs, when the slave UE 302 is actively communicating data traffic with the cellular network, the offloaded communication functions may include relay functions, whereby the master UE 304 exchanges application layer data traffic with the access network 306 on the physical layer on behalf of the slave UE 302, and then relays the application layer data traffic with the slave UE 302 via the D2D connection. In some designs, the offloaded communication functions may include radio resource management (RRM) and mobility management.

[0077] At 510, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) performs one or more offloaded communication functions on behalf of the slave UE, the one or more offloaded communication functions including transmission of control plane signaling associated with a security credential set assigned to the slave UE (e.g., to maintain the attachment of the slave UE 302 to the core network). As mentioned above with respect to 506, in addition to transmission of control plane signaling associated with the security credential set of the slave UE, the master UE 304 may also (optionally) offload generation, processing, encryption, and decryption of control plane signaling using the security credential set of the slave UE 302 without participation of the slave UE 302. In some designs, the offloaded communication functions may include paging monitoring functions and transmission of service requests initiated by the mobile station.

[0078] At 512, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) relays application layer data between the application server 310 and the slave UE 302 via the D2D connection. The application layer data (or data plane traffic) may include mobile originated (MO) data, mobile terminated (MT) data, or a combination thereof. In some designs, the application layer data may be exchanged at 512, wherein the tethering between the slave UE 302 and the master UE 304 remains transparent to the application server 310.

[0079] At 514, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally sends a request to generate a control message (e.g., control plane signaling) to the slave UE 302. The request 514 can be sent over the D2D connection. In an example, the request sending at 514 is optional because the generation, processing, encryption, and decryption of the control plane signaling can be offloaded to the master UE 304 instead, in which case the master UE 304 will generate the control message itself without the participation of the slave UE 302. In an example, the control message can correspond to a control plane registration update message or a tracking area update (TAU) message.

[0080] At 516, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258) optionally receives a control message from the slave UE 302. The optional reception of 516 may occur over the D2D connection. As mentioned above, reception 516 is optional because the generation, processing, encryption, and decryption of control plane signaling may be offloaded to the master UE 304 instead, in which case the master UE 304 will generate the control message itself without the participation of the slave UE 302.

[0081] At 518, the primary UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, TX MIMO processor 266, modulators 254a ... 254r, TX processor 264) optionally sends a control message (e.g., control plane signaling) to the core network 308. As mentioned above, the control message may correspond to a control plane registration update message or a tracking area update (TAU) message (e.g., NAS / AS signaling).

[0082] At 520, the master UE 304 (e.g., the controller / processor 280) optionally determines that the slave UE 302 is to resume execution of the communication functions offloaded from 508. In some designs, the optional determination of 520 may occur in response to a link quality associated with the D2D connection falling below a threshold. In some designs, the optional determination of 520 may occur in response to a teardown (e.g., untethering) of the D2D connection.

[0083] At 522, the master UE 304 (e.g., controller / processor 280, antennas 252a ... 252r, demodulators 254a ... 254r, MIMO detector 256, RX processor 258) optionally sends information to the slave UE 302 over the D2D connection to facilitate resumption of one or more offloaded communication functions. For example, the information sent at 522 may include system information, measurements, uplink and downlink timing, etc., so that the slave UE 302 does not need to re-collect such information. In some designs, the slave UE 302 and the master UE 304 may have different supported bandwidths and / or other capabilities (e.g., because the slave UE 302 may be an NR light or RedCap UE, or any type of UE with low available processing capacity and / or low battery condition), which may result in different applicable system parameters or measurements. In such a case, an offset (e.g., configured by the network or defined in the 3GPP specification) may be applied.

[0084] Figure 6An example communication path 600 (e.g., a control plane signaling path and a user plane (or data plane) service path) of a communication system 300 according to an embodiment of the present disclosure is shown. Specifically, the control plane signaling path and the user plane (or data plane) service path are in Figure 4 410 or Figure 5 An example of such a path is achieved when the slave UE 302 is D2D connected (or tethered) to the master UE 304 after offloading of 508.

[0085] refer to Figure 6 , depicts modules related to control plane signaling and user plane (or data plane) services. Other modules may also exist, but they are omitted for clarity. Figure 6 The RAN 306 is also not depicted in FIG, but is understood to be present in both the control plane signaling path and the user plane (or data plane) traffic path.

[0086] exist Figure 6 , slave UE 302 includes application layer module 602, TCP / IP module 604, NAS / AS module 606, and PAN module 608. Master UE 304 similarly includes application layer module 612, TCP / IP module 614, PAN module 616, and NAS / AS module 618. TCP / IP module 634.

[0087] Reference Figure 6 , the user plane (or data plane) service path (in forward or reverse order) includes application layer module 602, TCP / IP module 604, PAN module 608, PAN module 616, TCP / IP module 614, NAS / AS module 618, NAS / AS module 626, TCP / IP module 624, TCP / IP module 634 and application layer module 632. The control plane signaling path includes NAS / AS module 606, PAN module 608, PAN module 616, NAS / AS module 618 and NAS / AS module 626.

[0088] exist Figure 6 In the configuration of Figure 4 408 and Figure 5506 is not performed, so that the slave UE 302 continues to use the security credential set of the slave UE 302 to perform generation, processing, encryption and decryption of control plane signaling while being tethered to the master UE 304. For example, the slave UE 302 generates a TAU message and sends the TAU message to the master UE 304 on the D2D connection. The master UE 304 then encapsulates the TAU message into the master UE 304's own NAS message, which is then transmitted to the core network 308. The master UE 304 monitors the paging occasion for the paging message (which is not encrypted) for the slave UE 302. If there is MT data for the slave UE 302, the slave UE 302 performs a service request (e.g., a service request generated / encrypted at the slave UE 302 and sent to the master UE 304 for NAS encapsulation / transmission to the core network 308) via a tunnel through the master UE 304. MO data can be processed in a similar manner (on the reverse path). In this implementation, the packet data convergence protocol (PDCP) identity of the slave UE 302 is retained on the slave UE 302, while the radio network control (RLC) and medium access control (MAC) entities of the slave UE 302 are transferred to the master UE 304. In this case, the tethering between the slave UE 302 and the master UE 304 will be transparent to both the core network 308 and the application server 310. Figure 7-Figure 9 Describes in more detail Figure 6 The communication path 600.

[0089] Figure 7 An embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation 700 of the processes 400-500 is provided.

[0090] Reference Figure 7At 702, the master UE 304 performs an initial attach procedure with the core network 308. At 704, the slave UE 302 performs an initial attach procedure with the core network 308. At 706, the slave UE 302 and the master UE 304 establish a PAN link (e.g., a D2D connection) therebetween. At 708, the slave UE 302 sends information related to the cellular connection of the slave UE, such as the UE ID of the slave UE 302, paging occasions, etc. to the master UE 304. At 710, the master UE 304 sends its UE capability information to the slave UE 302. At 712, the slave UE 302 uses its security credentials to generate, encrypt, and send a UE capability update message (which references the capabilities of the master UE 304) to the master UE 304. At 714 , the master UE 304 encapsulates the UE capability update message in its own NAS message and sends the encapsulated UE capability update message (which references the capabilities of the master UE 304 ) to the core network 308 .

[0091] Reference Figure 7 At 716, the master UE 304 performs paging monitoring on behalf of the slave UE 302 in all RRC states (the slave UE 302 stops paging monitoring at this moment). In some designs, the master UE 304 notifies the slave UE 302 (e.g., in some implementations, the slave UE 302 and the master UE 304 may be associated with the same tracking area) when there is a change in the tracking area. At 718 (e.g., in response to a change in the tracking area associated with the slave UE 302), the master UE 304 requests the slave UE 302 to generate a registration update message. At 720, the slave UE 302 generates, encrypts, and sends a registration update message to the master UE 304 using its security credentials. At 722, the master UE 304 encapsulates the registration update message in its own NAS message and sends the encapsulated registration update message to the core network 308.

[0092] Figure 8 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation 800 of the processes 400-500 is provided. Specifically, Figure 8 The process 800 is Figure 7 Continuation of process 700 .

[0093] Reference Figure 8At 802, the application server 310 sends the MT data to the RAN 306 for transmission to the slave UE 302. At 804, assuming that the master UE 304 is in RRC idle / inactive, the RAN 306 sends a paging message for the slave UE 302, which is received at the master UE 304 by means of the offloaded paging monitoring function. At 806, the master UE 304 forwards the paging message to the slave UE 302 on the PAN link. At 808, the slave UE 302 generates, encrypts and sends a service request message to the master UE 304 using its security credentials. At 810, the master UE 304 encapsulates the service update message in its own NAS message and sends the encapsulated service update message to the core network 308 to perform RRC establishment. At 812, the MT data is sent by the RAN 306 and received at the master UE 304. At 814, the master UE 304 sends the MT data over the PAN link to the slave UE 302. In an alternative example, if the master UE 304 is not in RRC idle / inactive when the MT data is received at 802, 804-810 may be omitted and the RAN 306 may proceed directly to 812.

[0094] At some later point in time, the slave UE 302 determines that data (MO data) is to be sent back to the application server 310. At 816, assuming that the master UE 304 is in RRC idle / inactive, the slave UE 302 uses its security credentials to generate, encrypt, and send a service request message to the master UE 304. At 820, the master UE 304 encapsulates the service update message in its own NAS message and sends the encapsulated service update message to the core network 308 to perform RRC establishment. At 824, the slave UE 302 sends the MO data to the master UE 304 over the PAN link. At 826, the master UE 304 sends the MO data to the RAN 306. At 828, the RAN 306 forwards the MO data to the application server 310. In an alternative example, if the master UE 304 is not in RRC idle / inactive at 816, 818-820 can be omitted, and the slave UE 302 can proceed directly to 824.

[0095] like Figure 8As shown, the master UE 304 can perform mobility procedures (e.g., RRC establishment and data transmission / reception on behalf of the slave UE 302 on the RAN 306). In addition, when the master UE 304 is in RRC connected mode, random access channels (RACH) and data transmissions in the PHY / MAC / RLC layers do not require the slave UE 302 security credential set for encryption / decryption. Therefore, when the slave UE 302 is tethered to the master UE 304, these aspects can become part of the offloaded communication functions handled by the master UE 304. Specifically, the master UE 304 can perform various procedures at the PHY / MAC / RLC layers to send / receive PDCP PDUs on behalf of the slave UE 302 (e.g., although the slave UE 302 can continue to operate its own PDCP).

[0096] Fig. 9 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation 900 of the processes 400-500 is provided. Specifically, Fig. 9 The process 900 is Figure 8 Continuation of process 800 .

[0097] Reference Fig. 9 At 902-906, the various components 302-310 transmit MT and MO data, as described above with respect to Figure 8 As described. At 908, the slave UE 302 detects that the PAN link quality has fallen below a threshold. In some designs, the determination of 908 may alternatively be made at the master UE 304 and then reported to the slave UE 302. At 910, the master UE 304 sends information (e.g., system information, measurements, uplink and downlink timing, etc.) to the slave UE 302 over the PAN link to assist the slave UE 302 in recovering the offloaded communication functions (e.g., so that the slave UE 302 does not need to re-collect such information). At 912, the slave UE 302 uses its security credentials to generate, encrypt, and send a UE capability update message (which references the capabilities of the slave UE 302) to the core network 308. At 914-916, the slave UE 302 begins communicating directly with the application server 310 (i.e., without the participation or facilitation of the master UE 304).

[0098] Reference Fig. 9 , the master UE 304 can perform RRM and mobility procedures on behalf of the slave UE 302 so that the slave UE 302 does not need to know which cell or RAT is connected to the master UE 304.

[0099] Fig.10An example communication path 1000 (e.g., a control plane signaling path and a user plane (or data plane) traffic path) of a communication system 300 according to another embodiment of the present disclosure is shown. Specifically, the control plane signaling path and the user plane (or data plane) traffic path are in Figure 4 410 or Figure 5 An example of such a path is achieved when the slave UE 302 is D2D connected (or tethered) to the master UE 304 after the offload of 508. Fig.10 The modules of components 302-310 are similar to those described above. Figure 6 The discussion is the same and therefore will not be described again for the sake of brevity.

[0100] Reference Fig.10 , the user plane (or data plane) service path (in forward or reverse order) is consistent with the above Figure 6 However, Figure 6 Different, the control plane signaling path is specific to Figure 4 408 and Figure 5 506 is executed, so that the slave UE 302, when tethered to the master UE 304, offloads the generation, processing, encryption and decryption of control plane signaling using the security credential set of the slave UE 302. In other words, in an example, the master UE 304 is able to run the entire NAS / AS protocol stack on behalf of the slave UE 302. In this case, the NAS / AS protocol stack is effectively eliminated as in Figure 6 2 and 3. Control plane signaling between a slave UE 302 and a master UE 304 over a D2D connection (or PAN link) is shown in FIG. 2 (e.g., across the air interface, the master UE 304 operates like a dual subscriber identity module (SIM) dual standby (DSDA) phone with the slave UE 302 as one of its SIMs).

[0101] Accordingly, Fig.10 The control plane signaling path in the master UE 304 may include a PAN module 616, a NAS / AS module 618, and a NAS / AS module 626. As will be described in more detail below, the master UE 304 may perform generation, processing, encryption, and decryption of control plane signaling using a security credential set of the slave UE 302 without the participation of the slave UE 302. Figure 11-Figure 12 Describe in more detail Fig.10 The communication path 1000.

[0102] Fig.11 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation 1100 of the processes 400-500 is provided. Fig.11In the example, the slave UE 302 offloads all NAS / AS signaling to the master UE 304 , so that the master UE 304 runs the virtual SIM of the slave UE 302 .

[0103] Reference Fig.11 At 1102, the master UE 304 performs an initial attachment procedure with the core network 308. At 1104, the slave UE 302 and the master UE 304 establish a PAN link (e.g., a D2D connection) therebetween. The modified initial attachment from the UE 302 to the core network 308 will now be discussed in more detail.

[0104] Reference Fig.11 At 1106, the master UE 304 sends an attach request to the core network 308 on behalf of the slave UE 302 (e.g., effectively pretending to be the slave UE 302). At 1108, the core network 308 responds to the attach request from 1106 with an authentication request [RAND, AUTN]. At 1110, the master UE 304 forwards [RAND, AUTN] to the slave UE 302. At 1112, the slave UE 302 derives security keys [CK, IK, XRES]. At 1114, the slave UE 302 returns the derived security keys [CK, IK, XRES] to the master UE 304. At 1116, the master UE 304 sends an authentication response [XRES] to the core network 308. At 1118, the master UE 304 uses CK and IK to derive K ASME , K NASint and K NASenc At 1120, the master UE 304 sends a security command request to the core network 308. At 1122, the core network 308 responds to the security command request with a security command complete message. At 1124, the master UE 304 uses K ASME To derive K RRCint , K RRCenc and K UPenc At 1126, the core network 308 sends an Initial Context Setup message to the RAN 306. At 1128, the RAN 306 sends a Security Command Request to the master UE 304. At 1130, the master UE 304 responds to the Security Command Request with a Security Command Complete message. At 1132, the master UE 304 can now encrypt / decrypt NAS / AS signaling on behalf of the slave UE 302 without any further involvement of the slave UE 302.

[0105] Fig.12 Another embodiment according to the present disclosure is shown. Figure 4-Figure 5 An example implementation 1200 of the processes 400-500 is provided. Specifically, Fig.12The process 1200 is Fig.11 Continuation of process 1100 . Fig.12 The process 1200 is similar in some respects to Figure 8 process 800. However, with Figure 8 Unlike the process 800 of FIG. 8 , the slave UE 302 is completely bypassed with respect to control plane signaling, which is instead completely handled by the master UE 304. In other words, in FIG. Fig.12 In the embodiment, the slave UE 302 offloads all NAS / AS signaling to the master UE 304, so that the master UE 304 runs the virtual SIM of the slave UE 302 (for example, the master UE 304 performs functions similar to DSDC operation, whereby the PDCP entity of the slave UE 302 is located in the master UE 304).

[0106] Reference Fig.12 At 1202, the application server 310 sends the MT data to the RAN 306 for transmission to the slave UE 302. At 1204, assuming that the master UE 304 is in RRC idle / inactive, the RAN 306 sends a paging message for the slave UE 302 (e.g., in the slave UE 302's own paging occasion), which is received at the master UE 304 by means of the offloaded paging monitoring function (e.g., the master UE 304 monitors the paging occasion of the slave UE 302). At 1206, the master UE 304 uses the paging monitoring function via Fig.11 The process 1100 obtains the security credentials of the slave UE 302 to generate, encrypt and send a service request message to the core network 308 as part of the RRC establishment process. After the RRC is established, at 1208, the RAN 306 sends the MT data and the MT data is received at the master UE 304. At 1210, the master UE 304 sends the MT data to the slave UE 302 on the PAN link. Accordingly, at Fig.12 The process 1200 is omitted Figure 8 Furthermore, in an alternative example, if the master UE 304 is not in RRC idle / inactive when the MT data is received at 1202 , 1204 - 1206 may be omitted and the RAN 306 may proceed directly to 1208 .

[0107] At some later point in time, slave UE 302 determines that it wants to send data (MO data) back to application server 310. At 1214, slave UE 302 sends MT data to master UE 304 over the PAN link (without slave UE 302 taking into account the RRC state of master UE 304). At 1216, assuming master UE 304 is in RRC idle / inactive, master UE 304 uses Fig.11The master UE 304 uses the security credentials of the slave UE 302 obtained by the process 1100 to generate, encrypt and send a service request message to the core network 308 as part of the RRC establishment process. After the RRC is established, at 1218, the master UE 304 sends the MO data to the RAN 306. At 1220, the RAN 306 forwards the MO data to the application server 310. Fig.12 The process 1200 is omitted Figure 8 Furthermore, in an alternative example, if the master UE 304 is not in RRC idle / inactive at 1212, 1216 may be omitted and the master UE 304 may proceed directly to 1218.

[0108] Fig.13 is a conceptual data flow diagram 1300 illustrating the flow of data between different units / components in exemplary apparatuses 302 - 310 according to an embodiment of the present disclosure.

[0109] The slave UE 302 includes an application layer module 1302, which may correspond to the Figure 2 120 (including controller / processor 280 and memory 282). The slave UE 302 also optionally includes a control signaling module 1304, which may correspond to the control signaling module 1304 as shown in FIG. Figure 2 1 and 2. The processor circuitry in the UE 120 depicted in FIG. 1 (including the controller / processor 280 and the memory 282). The slave UE 302 also includes a cellular communication interface 1306 (e.g., 5G NR, etc.), which may include the processor circuitry in FIG. Figure 2 252r, modulators 254a...254r, TX MIMO processor 266, TX processor 264, demodulators 254a...254r, MIMO detector 256, RX processor, etc. The slave UE 302 also includes a D2D communication interface 1308 (e.g., Bluetooth, etc.), which may include the following: Figure 2 254a ... 254r, TX MIMO processor 266, TX processor 264, demodulators 254a ... 254r, MIMO detector 256, RX processor, etc.) in the UE 120 depicted in FIG.

[0110] The master UE 304 optionally includes a control signaling module 1322, which may correspond to the control signaling module 1322 as shown in FIG. Figure 2The main UE 304 also includes a cellular communication interface 1326 (e.g., 5G NR, etc.), which may include processor circuits (including controller / processor 280 and memory 282) in the UE 120 depicted in FIG. Figure 2 252r, modulators 254a...254r, TX MIMO processor 266, TX processor 264, demodulators 254a...254r, MIMO detector 256, RX processor, etc.). The master UE 304 also includes a D2D communication interface 1326 (e.g., Bluetooth, etc.), which may include the following: Figure 2 254a ... 254r, TX MIMO processor 266, TX processor 264, demodulators 254a ... 254r, MIMO detector 256, RX processor, etc.) in the UE 120 depicted in FIG.

[0111] RAN 306 includes a wireless interface 1332 (e.g., 5G NR, etc.) and a backhaul interface 1334 (e.g., for communicating with core network 308 and / or other network components). Core network 308 includes a backhaul interface 1342 (e.g., for communicating with RAN 306 and / or other network components). Core network 308 includes a communication interface 1344 (e.g., for communicating with nodes outside of the cellular network infrastructure, such as application servers 310 reachable via an Internet connection). Application server 310 includes a communication interface 1352 and an application layer module 1354 (e.g., for providing various services to clients such as slave UE 302 or master UE 304).

[0112] Reference Fig.13 , when the slave UE 302 is not tethered to the master UE 304, the slave UE 302 can communicate directly with the wireless interface 1332 of the RAN 306 via the cellular communication interface 1306. When tethered to the master UE 304, the slave UE 302 can alternatively route some of its cellular services to the master UE 304 via the D2D communication interfaces 1308 and 1326, and the master UE 304 in turn routes the cellular services of the slave UE to the RAN 306 via the cellular communication interface 1324. Control plane signaling (e.g., generation, processing, encryption, and decryption) can be processed at the control signaling module 1304 or the control signaling module 1322. Various UE-to-network control plane signaling can in turn be used to support end-to-end data plane services (or application layer services) exchanged between the application layer module 1302 and the application layer module 1354.

[0113] Fig.13 One or more components of the apparatus 302 and 304 may be executed in Figure 4-5 , Figure 7-9 and Figure 11-12 Each of the blocks of the algorithm in the aforementioned flowchart of Figure 4-5 , Figure 7-9 and Figure 11-12 Each block in the foregoing flow chart may be performed by a component of the slave UE 302 or the master UE 304. These components may be one or more hardware components specifically configured to perform the recited processes / algorithms, implemented by a processor configured to perform the recited processes / algorithms, stored in a computer-readable medium to be implemented by a processor, or some combination thereof.

[0114] Fig.14 1 is a diagram showing an example of a hardware implementation for a slave UE 302 employing a processing system 1414. The processing system 1414 may be implemented using a bus architecture, generally represented by a bus 1424. The bus 1424 may include any number of interconnecting buses and bridges, depending on the specific application of the processing system 1414 and the overall design constraints. The bus 1424 links together various circuits, including the processor 1404, one or more processors and / or hardware components represented by components 1302, 1304, 1306, and 1308, and the computer-readable medium / memory 1406. The bus 1424 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described any further.

[0115] The processing system 1414 may be coupled to the transceiver 1410. The transceiver 1410 is coupled to one or more antennas 1420. The transceiver 1410 provides a means for communicating with various other devices over a transmission medium. The transceiver 1410 receives signals from the one or more antennas 1420, extracts information from the received signals, and provides the extracted information to the processing system 1414 (specifically, the cellular communication interface 1306 or the D2D communication interface 1308). In addition, the transceiver 1410 receives information from the processing system 1414 (specifically, the cellular communication interface 1306 or the D2D communication interface 1308), and generates signals to be applied to the one or more antennas 1420 based on the received information. The processing system 1414 includes a processor 1404 coupled to a computer-readable medium / memory 1406. The processor 1404 is responsible for general processing, which includes executing software stored on the computer-readable medium / memory 1406. When executed by processor 1404, the software causes processing system 1414 to perform the various functions described above for any particular device. Computer-readable medium / memory 1406 may also be used to store data manipulated by processor 1404 when executing the software. Processing system 1414 also includes at least one of components 1302 or 1304. The component may be a software component resident / stored in computer-readable medium / memory 1406 running in processor 1404, one or more hardware components coupled to processor 1404, or some combination thereof. Processing system 1404 may be Figure 2 Components of the UE 120, and may include a TX processor 264, an RX processor 258, and at least one of a controller / processor 280 and / or a memory 282.

[0116] In one configuration, a slave UE 302 includes: means for establishing an attachment to a core network of a cellular communication system; means for obtaining a set of security credentials, the set of security credentials being configured to encrypt and decrypt traffic between the slave UE and the core network; means for establishing a device-to-device (D2D) connection with a master UE also attached to the core network; means for offloading one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network, the one or more offloaded communication functions including transmission of control plane signaling associated with the set of security credentials of the slave UE; and means for exchanging application layer data relayed by the master UE over the D2D connection and intended for or received from an application server. In some designs, the slave UE 302 also includes: means for continuing to perform, by the slave UE after offloading, at least one non-offloaded communication function (e.g., including one or more functions required to maintain the attachment of the slave UE to the core network). In some designs, the slave UE 302 further includes: a unit for determining that the execution of the one or more offloaded communication functions is to be resumed; and a unit for receiving, in response to the determination, a message from the master UE on the D2D connection to facilitate the resumption of the one or more offloaded communication functions; and a unit for sending, via the slave UE, a message reporting the capability information of the slave UE to the core network. In some designs, the slave UE 302 further includes: a unit for receiving, from the master UE on the D2D connection, a message from the master UE requesting the slave UE to generate a control message; a unit for generating a control message in response to the received message; and a unit for sending, over the D2D connection to the master UE, the control message to the master UE for transmission to the core network. In some designs, the slave UE 302 further includes: a unit for determining that the execution of the one or more offloaded communication functions is to be resumed; and a unit for receiving, in response to the determination, a message from the master UE on the D2D connection to facilitate the resumption of the one or more offloaded communication functions. The aforementioned means may be one or more of the aforementioned components of the UE 302 and / or a processing system 1414 of the UE 302 configured to perform the functions recited by the aforementioned means. As described above, the processing system 1414 may include the TX processor 264, the RX processor 258, and the controller / processor 280.

[0117] Fig.151 is a diagram showing an example of a hardware implementation for a host UE 304 employing a processing system 1514. The processing system 1514 may be implemented using a bus architecture, generally represented by a bus 1524. The bus 1524 may include any number of interconnecting buses and bridges, depending on the specific application of the processing system 1514 and the overall design constraints. The bus 1524 links together various circuits, including the processor 1504, one or more processors and / or hardware components represented by components 1322, 1324, and 1326, and the computer-readable medium / memory 1506. The bus 1524 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described any further.

[0118] The processing system 1514 may be coupled to the transceiver 1510. The transceiver 1510 is coupled to one or more antennas 1520. The transceiver 1510 provides a unit for communicating with various other devices over a transmission medium. The transceiver 1510 receives signals from the one or more antennas 1520, extracts information from the received signals, and provides the extracted information to the processing system 1514 (specifically, the cellular communication interface 1324 or the D2D communication interface 1326). In addition, the transceiver 1510 receives information from the processing system 1514 (specifically, the cellular communication interface 1324 or the D2D communication interface 1326), and generates signals to be applied to the one or more antennas 1520 based on the received information. The processing system 1514 includes a processor 1504 coupled to a computer-readable medium / memory 1506. The processor 1504 is responsible for general processing, which includes executing software stored on the computer-readable medium / memory 1506. When executed by processor 1504, the software causes processing system 1514 to perform the various functions described above for any particular device. Computer-readable medium / memory 1506 may also be used to store data manipulated by processor 1504 when executing the software. Processing system 1514 also includes component 1322. The component may be a software component resident / stored in computer-readable medium / memory 1506 running in processor 1504, one or more hardware components coupled to processor 1504, or some combination thereof. Processing system 1514 may be Figure 2 Components of the UE 120, and may include a TX processor 264, an RX processor 258, and at least one of a controller / processor 280 and / or a memory 282.

[0119] In one configuration, the master UE 304 includes: means for establishing an attachment to a core network of a cellular communication system; means for establishing a device-to-device (D2D) connection with a slave UE also attached to the core network; means for offloading one or more communication functions with the core network from the slave UE to the master UE, the one or more communication functions including at least one communication function for maintaining the attachment of the slave UE to the core network; means for performing one or more offloaded communication functions on behalf of the slave UE, the one or more offloaded communication functions including transmission of control plane signaling associated with a set of security credentials assigned to the slave UE; and means for relaying application layer data between an application server and the slave UE via the D2D connection. In some designs, the master UE 304 also includes: means for sending a message to the slave UE on the D2D connection requesting the slave UE to generate a control message; means for receiving a control message from the slave UE on the D2D connection; and means for sending a control message to the core network. In some designs, the master UE 304 further includes: a unit for determining that the slave UE is to resume performance of one or more offloaded communication functions; and a unit for sending information to the slave UE on the D2D connection to facilitate resumption of the one or more offloaded communication functions in response to the determination. The aforementioned means may be one or more of the aforementioned components of the slave UE 302 and / or a processing system 1414 of the slave UE 302 configured to perform the functions recited by the aforementioned means. As described above, the processing system 1414 may include the TX processor 264, the RX processor 258, and the controller / processor 280.

[0120] The previous description is provided to enable any person skilled in the art to practice the various aspects described in this article. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined in this article can be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown in this article, but to meet the full scope consistent with the claim expression, wherein, unless explicitly stated, reference to an element in a singular form is not intended to mean "one and only one", but to mean "one or more". The word "exemplary" used in this article means "used as an example, instance or illustration". Any aspect described as "exemplary" in this article is not necessarily interpreted as being preferred or advantageous over other aspects. Unless otherwise explicitly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B or C", "at least one of A, B and C" and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiples of A, multiples of B or multiples of C. Specifically, combinations such as "at least one of A, B, or C," "at least one of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members or some members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in this disclosure are expressly incorporated herein by reference and are intended to be covered by the claims, which structural and functional equivalents are known or will be known to those of ordinary skill in the art. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is expressly recited in the claims. No claim element is to be construed as a functional unit unless the element is expressly recited using the phrase "unit for..."

Claims

1. A method of operating a slave user equipment (UE), comprising: establishing an attachment to a core network of a cellular communication system; Obtaining a security credential set, wherein the security credential set is configured to encrypt and decrypt traffic between the slave UE and the core network; establishing a device-to-device (D2D) connection with a primary UE also attached to the core network; offloading one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network, the one or more offloaded communication functions including transmission of control plane signaling associated with a security credential set of the slave UE, The one or more offloaded communication functions include both of the following: (i) transmission of data plane traffic with the core network and transmission of control plane signaling with the core network, and (ii) generation, processing, encryption and decryption of the control plane signaling using the security credential set of the slave UE without participation of the slave UE; as well as The application layer data relayed by the master UE over the D2D connection and destined for or received from an application server is exchanged.

2. The method according to claim 1, further comprising: After the offloading, at least one non-offloaded communication function continues to be performed by the slave UE.

3. The method according to claim 2, in, The control plane signaling is transmitted between the slave UE and the master UE on the D2D connection.

4. The method according to claim 3, wherein: The uninstallation includes: receiving, from the master UE over the D2D connection, an indication of capability information for the master UE; and A message reporting the capability information for the master UE as capability information for the slave UE is sent over the D2D connection for transmission by the master UE to the core network.

5. The method according to claim 4, further comprising: determining to resume performance of the one or more offloaded communication functions; In response to the determination: receiving, from the master UE over the D2D connection, information for facilitating the resumption of the one or more offloaded communication functions; as well as A message reporting the capability information of the slave UE is sent by the slave UE to the core network.

6. The method according to claim 3, further comprising: receiving a message from the master UE on the D2D connection, the message being used to request the slave UE to generate a control message; generating the control message in response to the received message; as well as On the D2D connection to the master UE, the control message is sent to the master UE via the D2D connection for transmission to the core network.

7. The method according to claim 6, in, The control message is a control plane registration update message, or The control message is a Tracking Area Update (TAU) message.

8. The method according to claim 1, wherein: The control plane signaling includes non-access stratum (NAS) / access stratum (AS) signaling.

9. The method according to claim 1, wherein: The uninstallation includes: The security credential set of the slave UE is sent to the master UE over the D2D connection to facilitate the master UE to perform encryption and decryption of control plane signaling using the security credential set of the slave UE without participation of the slave UE.

10. The method according to claim 1, wherein: The one or more offloaded communication functions include paging monitoring functions and transmission of mobile station initiated service requests.

11. The method according to claim 1, wherein: The one or more offloaded communication functions include radio resource management (RRM) and mobility management.

12. The method according to claim 1, further comprising: determining to resume performance of the one or more offloaded communication functions; In response to the determining, information for facilitating the restoration of the one or more offloaded communication functions is received from the master UE over the D2D connection.

13. The method according to claim 1, wherein: After the offloading, the application layer data is transmitted over the core network using a data forwarding address set to an Internet Protocol (IP) address associated with the slave UE.

14. A method of operating a primary user equipment (UE), comprising: establishing an attachment to a core network of a cellular communication system; establishing a device-to-device (D2D) connection with a slave UE also attached to the core network; offloading one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network; performing one or more offloaded communication functions on behalf of the slave UE, the one or more offloaded communication functions comprising transmission of control plane signaling associated with a set of security credentials assigned to the slave UE, The one or more offloaded communication functions include both of the following: (i) transmission of data plane traffic with the core network and transmission of control plane signaling with the core network, and (ii) generation, processing, encryption and decryption of the control plane signaling using the security credential set of the slave UE without participation of the slave UE; as well as Application layer data is relayed between an application server and the slave UE via the D2D connection.

15. The method according to claim 14, wherein: The one or more offloaded communication functions do not include at least one non-offloaded communication function that continues to be performed by the slave UE during the performing.

16. The method according to claim 15, in, The control plane signaling is transmitted between the slave UE and the master UE on the D2D connection.

17. The method according to claim 16, wherein: The uninstallation includes: sending an indication of capability information for the master UE to the slave UE over the D2D connection; receiving, from the slave UE on the D2D connection, a message reporting the capability information for the master UE as capability information for the slave UE; and The message is sent to the core network.

18. The method according to claim 16, further comprising: Sending, over the D2D connection, to the slave UE a message for requesting the slave UE to generate a control message; receiving the control message from the slave UE over the D2D connection; as well as The control message is sent to the core network.

19. The method according to claim 18, in, The control message is a control plane registration update message, or The control message is a Tracking Area Update (TAU) message.

20. The method according to claim 14, wherein: The control plane signaling includes non-access stratum (NAS) / access stratum (AS) signaling.

21. The method according to claim 14, wherein: The uninstallation includes: receiving a set of security credentials of the slave UE from the slave UE over the D2D connection, The execution performs generation, processing, encryption, and decryption of the control plane signaling using a security credential set of the slave UE without participation of the slave UE.

22. The method according to claim 14, wherein: The one or more offloaded communication functions include paging monitoring functions and transmission of mobile station initiated service requests.

23. The method according to claim 14, wherein: The one or more offloaded communication functions include radio resource management (RRM) and mobility management.

24. The method of claim 14, further comprising: Determining that the slave UE is to resume execution of the one or more offloaded communication functions; In response to the determination, information for facilitating the resumption of the one or more offloaded communication functions is sent to the slave UE over the D2D connection.

25. The method of claim 14, wherein: During the execution, the application layer data is transmitted over the core network using a data forwarding address set to an Internet Protocol (IP) address associated with the slave UE.

26. A slave user equipment (UE), comprising: Memory; as well as at least one processor coupled to the memory and configured to: establishing an attachment to a core network of a cellular communication system; Obtaining a security credential set, wherein the security credential set is configured to encrypt and decrypt traffic between the slave UE and the core network; establishing a device-to-device (D2D) connection with a primary UE also attached to the core network; offloading one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network, the one or more offloaded communication functions including transmission of control plane signaling associated with a security credential set of the slave UE, The one or more offloaded communication functions include both of the following: (i) transmission of data plane traffic with the core network and transmission of control plane signaling with the core network, and (ii) generation, processing, encryption and decryption of the control plane signaling using the security credential set of the slave UE without participation of the slave UE; as well as The application layer data relayed by the master UE over the D2D connection and destined for or received from an application server is exchanged.

27. The slave UE according to claim 26, in, The one or more offloaded communication functions include a paging monitoring function and transmission of a mobile station initiated service request, or The one or more offloaded communication functions include radio resource management (RRM) and mobility management, or Its combination.

28. The slave UE according to claim 26, wherein the at least one processor is further configured to: After the offloading, at least one non-offloaded communication function continues to be performed by the slave UE.

29. The slave UE according to claim 28, in, The control plane signaling is transmitted between the slave UE and the master UE on the D2D connection.

30. The slave UE according to claim 29, wherein: The uninstallation includes: receiving, from the master UE over the D2D connection, an indication of capability information for the master UE; and A message reporting the capability information for the master UE as capability information for the slave UE is sent over the D2D connection for transmission by the master UE to the core network.

31. The slave UE according to claim 30, wherein the at least one processor is further configured to: determining to resume performance of the one or more offloaded communication functions; In response to the determination: receiving, from the master UE over the D2D connection, information for facilitating the resumption of the one or more offloaded communication functions; and A message reporting the capability information of the slave UE is sent by the slave UE to the core network.

32. The slave UE according to claim 29, wherein the at least one processor is further configured to: receiving a message from the master UE on the D2D connection, the message being used to request the slave UE to generate a control message; generating the control message in response to the received message; as well as On the D2D connection to the master UE, the control message is sent to the master UE via the D2D connection for transmission to the core network.

33. The slave UE according to claim 26, wherein: The uninstallation includes: The security credential set of the slave UE is sent to the master UE over the D2D connection to facilitate the master UE to perform encryption and decryption of control plane signaling using the security credential set of the slave UE without participation of the slave UE.

34. The slave UE according to claim 26, wherein the at least one processor is further configured to: determining to resume performance of the one or more offloaded communication functions; In response to the determining, information for facilitating the restoration of the one or more offloaded communication functions is received from the master UE over the D2D connection.

35. A primary user equipment (UE), comprising: Memory; as well as at least one processor coupled to the memory and configured to: establishing an attachment to a core network of a cellular communication system; establishing a device-to-device (D2D) connection with a slave UE also attached to the core network; offloading one or more communication functions from the slave UE to the master UE, the one or more communication functions including at least one communication function with the core network for maintaining the attachment of the slave UE to the core network; performing one or more offloaded communication functions on behalf of the slave UE, the one or more offloaded communication functions comprising transmission of control plane signaling associated with a set of security credentials assigned to the slave UE, The one or more offloaded communication functions include both of the following: (i) transmission of data plane traffic with the core network and transmission of control plane signaling with the core network, and (ii) generation, processing, encryption and decryption of the control plane signaling using the security credential set of the slave UE without participation of the slave UE; as well as Application layer data is relayed between an application server and the slave UE over the D2D connection.

36. The master UE according to claim 35, wherein: The one or more offloaded communication functions do not include at least one non-offloaded communication function that continues to be performed by the slave UE during the performing.

37. The master UE according to claim 35, in, The control plane signaling is transmitted between the slave UE and the master UE on the D2D connection.

38. The master UE according to claim 36, wherein: The uninstallation includes: sending an indication of capability information for the master UE to the slave UE over the D2D connection; receiving, from the slave UE on the D2D connection, a message reporting the capability information for the master UE as capability information for the slave UE; and The message is sent to the core network.

39. The master UE of claim 36, wherein the at least one processor is further configured to: Sending, over the D2D connection, to the slave UE a message for requesting the slave UE to generate a control message; receiving the control message from the slave UE over the D2D connection; as well as The control message is sent to the core network.

40. The master UE according to claim 35, wherein: The uninstallation includes: receiving a set of security credentials of the slave UE from the slave UE over the D2D connection, The execution performs generation, processing, encryption, and decryption of the control plane signaling using a security credential set of the slave UE without participation of the slave UE.

41. The master UE according to claim 35, wherein: The one or more offloaded communication functions include paging monitoring functions and transmission of mobile station initiated service requests.

42. The master UE according to claim 35, wherein: The one or more offloaded communication functions include radio resource management (RRM) and mobility management.

43. The master UE of claim 35, wherein the at least one processor is further configured to: Determining that the slave UE is to resume execution of the one or more offloaded communication functions; In response to the determination, information for facilitating the resumption of the one or more offloaded communication functions is sent to the slave UE over the D2D connection.

Images