CN114223240B

CN114223240B - Paging optimization based on mobile device proximity

Info

Publication number: CN114223240B
Application number: CN202080051272.8A
Authority: CN
Inventors: A·施密特; A·卢夫特; M·别纳斯; M·汉斯
Original assignee: Ipcom GmbH and Co KG
Current assignee: Ipcom GmbH and Co KG
Priority date: 2019-07-17
Filing date: 2020-07-17
Publication date: 2024-05-14
Anticipated expiration: 2040-07-17
Also published as: CN114223240A

Abstract

The present invention provides a method of performing paging actions for a second user equipment, a UE and a device in a mobile communication system, the method comprising transmitting a configuration message from a first base station to a first UE device to configure the first UE device to transmit a paging indication at a predetermined time if it is determined that a geographical condition is met; and transmitting a paging message from one of the first base station and the second base station to the second UE device after the paging indication is sent.

Description

Paging optimization based on mobile device proximity

Technical Field

The present invention relates to a paging procedure in a cellular communication system, e.g. a cellular communication system operating according to the 3GPP 4G-LTE suite of specifications or its subsequent technology (commonly referred to as 5G-NR).

Background

In 4G-LTE, the Radio Access Network (RAN) consists of base stations called enbs, providing user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol termination to mobile communication devices (UEs). The enbs are interconnected via an X2 interface. The eNB is also connected with a Core Network (CN) through an S1 interface, more specifically, is connected with a Mobility Management Entity (MME) responsible for C-plane communication service through an S1-MME interface and is connected with a service gateway (S-GW) responsible for U-plane communication service through an S1-U interface. The S1 interface supports a many-to-many relationship between MME/S-GW and eNB.

Disclosure of Invention

Each base station of a cellular communication system may control the communication of the air interface within its geographical coverage area, i.e. within its radio cell. When a mobile communication device (UE) is located within the coverage of one radio cell and camps thereon (in other words, when it registers with the radio cell providing coverage), it may communicate with a base station controlling that radio cell. When a user of a mobile communication device initiates a call or the call is addressed to the mobile communication device, a radio channel may be established between the mobile communication device and a base station controlling a radio cell in which the mobile communication device is located.

As the mobile communication device continues to move throughout the coverage area of the cellular communication system, control of the call may be transferred between adjacent radio cells. The transfer of a call from one radio cell to another is often referred to as handover (or handoff). The handover is typically based on measurements made by the UE of the network configuration (e.g., for different overlapping and/or neighboring radio cells).

In this case, the term "call" is intended to cover various situations where user data is exchanged, either unidirectionally or bidirectionally, over the air interface, as part of an active connection between the serving base station and the mobile communication device. For example, it may be a voice telephone, a data telephone, internet data traffic, and other forms.

Another interface for device-to-device direct communication (D2D) is defined in 3 GPP. Such interfaces are illustrated in fig. 1 using the term 4G-LTE. The same interface exists in the following technology 5G-NR of 3 GPP.

Two mobile communication devices (UEs) within or outside the coverage of a system radio cell may communicate with each other to enable certain services (or applications), such as "public safety" or "car-to-car communication. For the case that direct communication from device to device must be performed in an area where network coverage is not guaranteed, three different usage scenarios have been proposed by 3GPP

(1) Case in coverage: the network controls resources for D2D communication.

(2) Out of coverage conditions: the UE uses resources preconfigured in the USIM of the mobile device or UICC card. However, the term "out of coverage" must be interpreted carefully. It does not mean no coverage at all, but no coverage on the frequency used for D2D communication, although the UE may be covered on another carrier for cellular communication.

(3) Partial coverage case: the UE outside the coverage uses a pre-configured value, while the UE within the coverage obtains its resources from the base station. Careful coordination of the network and preset values is necessary to achieve communication and limit interference generated by UEs located near cell boundaries in the vicinity of out-of-coverage UEs.

In conventional cellular communications, e.g., over the LTE Uu air interface, the eNB communicates with the UE in the Uplink (UL) direction (i.e., from the handset to the tower) and in the Downlink (DL) direction (i.e., from the tower to the handset). As the LTE PC5 air interface introduces a Sidelink (SL), this concept is extended to use cases of direct communication between various devices.

Drawings

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a connection for direct communication from device to device in accordance with 3GPP specifications;

Fig. 2 illustrates radio resource control states and state transitions between 4G-LTE and 5G-NR;

FIG. 3 illustrates one example of a paging message;

Fig. 4 illustrates one example of a subframe structure defined for 4G-LTE;

FIG. 5 illustrates a schematic diagram of a message transmitted in accordance with the present invention;

FIG. 5a illustrates the transmission of a paging indication and a paging message;

Fig. 6 is an information sequence diagram illustrating an embodiment of the present invention when two UEs are served by the same base station;

Fig. 7 is an information sequence diagram illustrating an embodiment of the present invention when two UEs are served by different base stations;

FIG. 8 illustrates a first configuration option;

FIG. 9 illustrates a second configuration option;

fig. 10 illustrates a paging indication transmitted in a sidelink resource;

Fig. 11 illustrates a paging indication transmitted in downlink resources; and

Fig. 12 illustrates a case where the paging indication and the paging message are not transmitted in the same subframe.

Detailed Description

Fig. 2 illustrates a Radio Resource Control (RRC) protocol state diagram according to 3gpp TS 38.331. The figure also illustrates inter-RAT mobility support between 4G-LTE (left schematic) and 5G-NR (right schematic).

After the RRC connection is established, the mobile communication device (UE) is either in an rrc_connected state or in an rrc_inactive state. If this is not the case, i.e. no RRC connection is established, the UE is in rrc_idle state. The RRC state may be further described as follows:

RRC_IDLE：

-UE-specific DRX is configurable by upper layers;

Mobility controlled by the UE (based on network configuration);

-the UE monitoring DL control channels to detect paging indications;

-the UE performs neighbor cell measurements and cell (re) selection;

the UE acquires system information and may send SI requests (if configured).

RRC_INACTIVE：

-UE-specific DRX may be configured by an upper layer or RRC layer;

Mobility controlled by the UE (based on network configuration);

-the UE storing a "UE inactive" Access Stratum (AS) context;

-a RAN-based notification area configured by the RRC layer;

-the UE monitoring DL control channels to detect paging indications;

-the UE performs neighbor cell measurements and cell (re) selection;

-the UE performing a RAN-based notification area update;

acquire system information and may send SI requests (if configured).

RRC_CONNECTED:

-The UE storing a "UE activated" Access Stratum (AS) context;

-unicast data may be transmitted to/from the UE;

At lower layers, the UE may be configured with UE-specific DRX;

-for a UE supporting Carrier Aggregation (CA): one or more secondary cells (scells) may be aggregated with a particular cell (SpCell) to increase bandwidth;

-for a UE supporting Dual Connectivity (DC): one Secondary Cell Group (SCG) may be aggregated with a primary cell group (MCG) to increase bandwidth;

Mobility is controlled by the network;

-the UE monitoring DL control channels to detect paging indications;

-the UE monitoring a DL control channel to detect a resource allocation situation;

-the UE providing channel quality and feedback information;

-the UE performs neighbor cell measurements and measurement reporting;

-the UE acquiring system information.

Paging is a mechanism by which the infrastructure party tells the mobile communication device that "i have something to you". In most cases, the paging procedure is initiated when the mobile communication device is in a reduced power consumption state (e.g., in an RRC IDLE or RRC active mode of operation). Paging may also occur when a UE has a persistent connection with its serving base station (e.g., when in rrc_connected mode of operation).

In early wireless communication systems, such as 3G-UMTS, a special physical channel was provided in the downlink for mobile communication devices to detect paging information. This paging indication channel is specifically designed to enable the mobile communication device to periodically wake up its receiver (in a short period of time to minimize the impact on battery life) to detect a paging indication (typically assigned to a group of UEs). The mobile communication device will then keep its receiver on to receive longer messages indicating the exact identity of the called UE.

In the communication systems of 4G-LTE and 5G-NR, no such separate physical channel is used for this purpose. And a Physical Downlink Shared Channel (PDSCH) is used for paging messages, and an indication is provided through a Physical Downlink Control Channel (PDCCH). The duration of the PDCCH signaling is already short and therefore monitoring the PDCCH from time to time has a low impact on battery life. Thus, normal PDCCH signaling may be used to carry (equivalent to) paging indications, while detailed paging information is carried by PDSCH in the resource blocks indicated by PDCCH. The paging indication sent on the PDCCH uses a single fixed identity called P-RNTI (paging radio network temporary identity). Instead of providing different paging identifiers for different (group) UEs, the different (group) UEs are configured to monitor paging messages of different subframes (their paging occasions). A paging message typically consists of several paging records (up to 32), each for a particular UE. One UE may be identified by a UE-identity carried in a paging message. This in turn means that all UEs that accidentally obtain a paging indication (in their respective paging occasions) need to receive, decode and analyze the entire paging message, even if there is no paging record associated with them. In a practical deployment, the number of UEs sharing one paging occasion may be quite high (i.e. much larger than 32).

The paging procedure may be initiated in the following scenario:

Transmitting paging information to the UE maintained in the rrc_idle or rrc_inactive state to trigger an RRC connection setup or RRC connection recovery procedure (see fig. 2);

Notifying the change of SI (system information) to the UEs in the above three RRC states;

the UEs in the above three RRC states are informed of notification about PWS (public alert system).

Paging refers to the mobile communication device constantly monitoring certain downlink resources on the PDCCH to check if the network is sending a paging indication. The paging indication indicates that corresponding paging information is to be transmitted on the PDSCH.

In the context of the present invention, the term "paging data" includes "paging indication" (possibly in the form of a P-RNTI on the PDCCH) and the actual "paging message" (possibly transmitted on the PDSCH and possibly containing several "paging records" for different UEs). According to the prior art, in the PDSCH region of the same subframe, a "paging message" is always immediately followed by a "paging indication". A paging record is a set of information specific to a particular mobile communication device. Fig. 3 illustrates the structure of a known paging message defined for 4G-LTE.

A maximum of 32 paging records may be included in one paging message. Each paging record may include a UE-Identifier identity (e.g., IMSI or S-TMSI) and a CN-Domain indicator (e.g., representing a circuit switched "CS" or representing a packet switched "PS"). The remaining information elements relate to system information updates (SI modification) or various common warning system (PWS) indications, followed by further optional information elements (depending on the release number of the specification), such as parameters controlling access barring, inter-frequency re-allocation, or BCCH modification indications for UEs using eDRX.

In some cases, the structure of the paging message may be different from that shown in fig. 3 because it includes only one paging record list. In this case, the indication of SI modification and PWS is contained in a single 8-bit word, called "short message/sms", which may be carried on the PDCCH (in some types of DCI).

If a mobile communication device in either the rrc_idle or rrc_inactive mode of operation is paged, paging data received by the mobile communication device may trigger it to enter the full mode of operation. For example, if on the infrastructure side, user data is already available for the mobile communication device (an event called "downlink data arrival"), the mobile communication device may be called and changed from the rrc_idle or rrc_inactive operating state to the rrc_connected operating state (refer to the RRC connection restoration or RRC connection establishment procedure shown in fig. 2).

Fig. 4 shows a simplified version of a subframe structure of a downlink (tower-to-handset) resource grid used in a wireless communication system according to 4G-LTE. One subframe may include two regions, namely a Control Channel Region (CCR) and a Shared Channel Region (SCR). The CCR may (mainly) contain PDCCH/PCFICH physical channels, while the SCR may (mainly) contain PDSCH physical channels. For simplicity, the broadcast channel region (i.e., the region in which the PBCH physical channel is located) and the synchronization signals (e.g., P-SS and S-SS) are not shown in fig. 4. In the case of 4G-LTE, ten consecutive subframes constitute one radio frame with a total length of 10 milliseconds.

The subframe defined for 5G-NR may also contain one CCR and one SCR, but the arrangement of the regions may deviate slightly from that shown in fig. 4, since the resource grid of 5G-NR generally allows more flexibility.

For example, in 5G-NR, the CCR may be represented in the form of a set of control resources (CORESET) that do not extend the entire bandwidth of the carrier. Furthermore, the CCR of the 5G-NR may not be scheduled to occupy the first OFDM symbol in a given subframe. Nevertheless, the principles of the method described below are readily applicable to 5G-NR.

In order to effectively use radio resources, the paging procedure of 4G-LTE and 5G-NR is designed to have the following characteristics:

More than one mobile communication device monitors the same paging occasion on the PDCCH;

The list of paging records in the paging message enables the network to handle bursty paging requests, i.e., to handle transient high load paging requests;

thus, congestion of paging (i.e., paging messages cannot be sent) can be minimized.

From the UE perspective, receiving a paging indication at a given paging occasion requires all mobile communication devices assigned to that paging occasion to receive, decode and interpret the entire content of a subsequent paging message, which message typically consists of a plurality of (up to 32) paging records. It is an energy consuming process to review all of these records. All mobile communication devices that receive paging indications on their respective paging occasions are obliged to perform this procedure even if no special paging record is included in the paging message for them. In the most advanced technique, the number of UEs sharing one paging occasion may be quite high (i.e., much greater than 32).

Only mobile communication devices that find a matching UE-identity in any paging record will act on the paging message. It is likely that most mobile communication devices will eventually find a paging record that does not match it after having undergone the process of receiving, decoding and analyzing the content of the paging message. These devices parse the content of the paging message but are futile. In the context of the present invention, this is referred to as a "false alarm in paging" (FAP).

Document WO 2017/099837 A1 describes a UE as a relay for a remote UE. The processing circuitry of the remote UE detects a paging message from an eNodeB of the ProSe network on an air interface between the eNodeB and the remote UE, or a relay UE through the ProSe network on a PC5 interface between the relay UE and the remote UE.

WO 2018/028279 A1 (EP 3449975 A1) describes a technique for discontinuous reception over a PC5 interface, with a relay UE performing paging of a remote UE.

US 10,117,223 B1 describes a system in which a relay base station may be used to make a call to a corresponding device of a donor base station in communication with the relay base station. EP 3 113 548 A1 describes an arrangement in which in order for one UE to connect to another UE via a D2D sidelink, a first UE requests a serving eNB to call a second UE, which sends a page to the first UE.

In another aspect, the present invention provides a method of performing a paging action for a user equipment, UE, device in a mobile communication system, the method comprising configuring another UE device to transmit a paging indication when it is determined that the UE device satisfies a geographical condition; and transmitting a paging message from the base station to one of the UE devices after the paging indicator is transmitted.

The invention also provides a UE device arranged to receive a paging indication from another UE device and to configure itself to receive a paging message corresponding to the paging indication from a base station in response to the indication.

Preferred aspects of the invention are provided according to the dependent claims.

It is an object of the invention to minimize the number of false positives in paging. This is achieved by exploiting knowledge of the proximity of mobile communication devices capable of direct communication between the devices and configuring the relevant mobile communication devices accordingly. According to the invention, the paging indication is no longer transmitted over the Uu air interface within the entire coverage area of the radio cell. Conversely, when a paging indication is detected as being close, it is propagated by the selected mobile communication device to the associated neighboring mobile communication device over the PC5 air interface. The paged neighboring mobile communication device may then wake up to receive subsequent paging messages from the base station over the Uu air interface.

According to a first aspect of the invention, the first mobile communication device may be configured to propagate the paging indication over the PC5 air interface to a second mobile communication device that the network wishes to call. The second (paged) mobile communications device will receive subsequent paging messages from the base station over the Uu air interface. Thus, the two parts that make up the paging data (i.e., "paging indication" and "paging message") are decoupled from each other.

A second aspect of the present invention relates to identifying a proximity relationship between a first mobile communication device and a second (paged) mobile communication device. The second mobile communication device may be a stationary or quasi-stationary communication device whose location is known to the infrastructure side (at least at some boundaries). In one embodiment, the second mobile communication device is embedded in or connected to an internet of things (IoT) device, such as a smart meter, roadside device, vending machine, sensor, or actuator. In another embodiment, the second mobile communication device is configured to have a special sleep period that may be much longer than the sleep periods of other mobile communication devices in the same cellular communication network.

The configuration procedure of the first mobile communication device for implementing the method of the invention is a third aspect of the invention. Preferably configured when the communication device resides in an rrc_connected mode of operation. The configuration may include location information and/or time information to send the paging indication. The former may assist the first mobile communication device in sending a paging indication when in proximity to a second mobile communication device that the network wishes to call. The latter may assist the first mobile communication device in sending the paging indication to the second mobile communication device at the correct point in time (e.g., taking into account the sleep period of the second mobile communication device).

According to a fourth aspect of the invention, transmission of paging indications between adjacent mobile communication devices, whether on a sidelink or downlink radio resource, is enabled. In order to make this work free from any interference from PDCCH transmitted by the radio cell, certain refinements of resource coordination are described in the fifth aspect of the invention.

According to a fifth aspect of the invention, certain parts of the Control Channel Region (CCR) are not used (left blank) by the base station. This is arranged to avoid resource collision (interference) between subframes transmitted by the first mobile communication device over the PC5 interface and subframes transmitted by the base station over the Uu air interface.

According to a sixth aspect of the invention, a timing relationship is defined between a paging indication (sent according to the fourth aspect above) and a subsequent paging message (sent over the Uu air interface). Unlike most advanced deployments, such timing relationship may span different subframes (e.g., the control channel region transmitting the paging indication and the shared channel region transmitting the subsequent paging message may no longer be within the same subframe).

The invention can reduce the occurrence of FAP. In detail, the number of mobile communication devices that must undergo reception, decoding and analysis of the paging message content can be greatly reduced without actual paging. This is particularly advantageous for internet of things devices such as smart meters, sensors or actuators, which often have severe limitations in terms of power consumption.

The paging procedure may be improved by exploiting knowledge of the proximity of mobile communication devices capable of direct communication between the devices and configuring the location and time parameters of the participating mobile communication devices accordingly. According to the invention, the paging indication is no longer transmitted over the Uu air interface within the entire coverage area of the radio cell. Conversely, when a paging indication is detected as being close, it is propagated by the selected mobile communication device to the associated neighboring mobile communication device over the PC5 air interface. The paged neighboring mobile communication device may then wake up to receive subsequent paging messages from the base station over the Uu air interface.

A first aspect of the present invention relates to decoupling of paging indicators from paging messages.

The first mobile communication device may be configured by the infrastructure side to propagate the paging indication over the PC5 air interface (either on the sidelink radio resources or on the downlink radio resources by analog base station functionality) to a neighboring second mobile communication device that the network wishes to call. The second (paged) mobile communication device will receive subsequent paging messages of the base station over the conventional Uu air interface.

Fig. 5 depicts how the two parts that make up the paging data are decoupled from each other and sent from different entities: step 1 represents a configuration procedure of the mobile communication device, which will be discussed in more detail below in connection with the third aspect of the invention. In step 2, a paging indication is sent by the first mobile communication device (UE 1), step 3 describing the transmission of a paging message by the base station. The paging indication may be transmitted from UE1 to UE2 over the PC5 air interface on sidelink resources as shown in fig. 5 a. Another option for transmitting a paging indication from UE1 to UE2 is to let UE1 provide downlink resources (e.g. resources used on the Uu air interface) in order to emulate some base station functionality (not shown in fig. 5). These two different aspects are discussed in more detail below in connection with the fourth aspect of the invention.

Fig. 6 shows a message sequence chart according to an embodiment of the invention, wherein both the first mobile communication device (UE 1) and the second mobile communication device (UE 2) are served by the same base station. UE1 may be a regular UE and UE2 may be an internet of things device that may have been configured with a sleep period that is much longer than the sleep period of other regular communication devices in the same cellular communication network. The sleep period of the UE2 may be known to the infrastructure side (e.g. may be stored in a memory of the core network entity or RAN entity).

At point a of fig. 6, the base station BS1 decides (or receives an indication to do so from the core network) to configure (at least one) UE1 to transmit paging indications to other mobile communication devices in the vicinity (e.g., over the PC5 air interface). For this reason, the configuration information needs to contain some detailed information about the target mobile communication device (i.e. the device to be paged), e.g. at least one piece of information about the sleep period of the target device, the potential wake-up time, the configured paging occasion, location data, deployment details, preferred paging mode (e.g. on sidelink resources or downlink resources), etc. UE1 receives the configuration message at point B. From now on, UE1 will periodically or continuously check the time and/or location requirements for sending paging indications to nearby mobile communication devices. This is indicated by the point C in fig. 6. In some cases it may be advantageous to check certain parameters in a continuous sequence, for example, first checking the time criteria and then checking the location criteria (when a paging occasion is about to come or the sleep cycle is about to end). To this end, UE1 may compare the output of a GNSS receiver or similar positioning determination module with the position requirements received from the configuration information of the base station. If all of these (and possibly further criteria) are met (see point F), UE1 may send a paging indication (on sidelink resources or downlink resources as desired by UE 2) over the PC5 air interface to mobile communication devices in its vicinity. In this example, UE2 receives the paging indication at point G. Now, UE2 expects to receive a subsequent paging message sent by the base station at the correct point in time (e.g., after a relative amount of time tp). UE2 receives the paging message at point H. This message can now be processed to find a matching paging record. Thus, further activities (such as random access attempts to the base station BS 1) may be initiated.

Fig. 7 shows a message sequence chart according to another embodiment of the invention, wherein a first mobile communication device (UE 1) and a second mobile communication device (UE 2) are served by different base stations. Also, UE1 may be a regular UE and UE2 may be an internet of things device, which may be configured with a sleep period that is much longer than the sleep period of other regular communication devices in the same cellular communication network. The sleep period of the UE2 may be known to the infrastructure side (and may be stored, for example, in a memory of the core network entity or RAN entity).

At point a' of fig. 7, the base station BS1 decides (or receives an indication to do so from the core network or from other RAN nodes, e.g. base station BS 2) to configure (at least one) UE1 to transmit paging indications to other mobile communication devices in the vicinity (e.g. over the PC5 air interface). In this example scenario, another mobile communication device (i.e., the device to be paged) is served by the base station BS 2. The configuration message needs to contain some detailed information about the target mobile communication device, e.g., should have at least one piece of information about the target device's sleep period, potential wake-up time, configured paging occasion, location data, deployment details, preferred paging mode (e.g., on sidelink resources or downlink resources), etc. In addition, the configuration message needs to contain base station related information (e.g., base station identification directed to BS 2) serving other mobile communication devices. UE1 receives the configuration message at point B'. From now on, UE1 will periodically or continuously check the time and/or location requirements for sending paging indications to nearby mobile communication devices. This is indicated by the point C' in fig. 7. In some cases it may be advantageous to check certain parameters in a continuous sequence, for example, first checking the time criteria and then checking the location criteria (when a paging occasion is about to come or the sleep cycle is about to end). To this end, UE1 may compare the output of a GNSS receiver or similar positioning determination module with the position requirements received from the configuration message of the base station. If certain criteria are met (see point D'), UE1 may initiate a random access procedure to base station BS2 to obtain a Timing Advance (TA) value for communication between base station BS2 and UE 2. UE1 receives the random access response information containing TA1 at the E' point. We assume here that the distance between UE1 and UE2 is relatively small (e.g. in the range of 100 meters or less), so the timing advance value (TA 1) of the communication between base station BS2 and UE1 and the timing advance value (TA 2) of the communication between base station BS2 and UE2 are the same or at least very similar. When all transmission criteria (as defined in the configuration message) are met, UE1 may calculate the exact time to transmit the paging indication to the mobile communication devices in its vicinity (see point F') taking into account the timing advance value (TA 2) of the communication between base station BS2 and UE2 derived from TA 1. UE1 may transmit the paging indication on a sidelink resource or a downlink resource over the PC5 air interface, as desired by UE 2. In this example, UE2 receives the paging indication at point G'. Now, UE2 is expected to receive a subsequent paging message transmitted by its serving base station BS2 at the correct point in time (e.g. after a relative amount of time tp). The UE2 receives the paging message at the H' point. This message can now be processed to find a matching paging record. Thus, further activities (such as random access attempts to the base station BS 2) may be initiated.

The D 'and E' points in fig. 7 represent a simple random access procedure ("2-Step RACH") that contains only two messages. In some embodiments, the random access procedure consists of a total of four messages ("4-Step RACH") exchanged between UE1 and BS 2. We further propose to extend the range of values of the information element "establishment cause" which can be used, for example, for RRC connection setup message (in the case of 4G-LTE, this is the third message exchanged during the "4-step RACH" random access procedure, not shown in fig. 7) enabling UE1 to signal to base station BS2 that its purpose of said random access attempt is to find the Timing Advance (TA) of another mobile communication device in its vicinity according to the paging method disclosed in the present invention. For example, the new value of "establishment cause" may be set to "timing-advance for-PC 5" (or the like). When the base station receives the RRC connection setup message with "setup cause" set to such new values, it will know that the purpose of this random access procedure is not to set up a bearer between the UE1 and the core network for instant messaging. It will therefore alleviate some of the processing burden of the base station. This also helps to inhibit load balancing operations, if any.

A second aspect of the invention relates to identifying adjacency.

Using the known "D2D ProSe direct discovery" procedure would be an option to detect proximity between two mobile communication devices. However, this process is accompanied by an exchange of information over the air interface of the PC 5.

In the present case, the goal is to have the second mobile communication device remain in sleep mode for as long as possible. Thus, it is not envisaged to have the second mobile communication device communicate any extensive information with potential nearby devices over the PC5 air interface.

Thus, in order for the proposed method to be satisfactorily implemented, the first mobile communication device needs to be provided by the network with a paging occasion adapted to the potential second mobile communication device (at a specific location). The infrastructure will need to maintain a database for this in either the RAN (for RAN initiated paging if the relevant second mobile communication device resides in rrc_inactive mode of operation) or the CN (for CN initiated paging if the relevant second mobile communication device resides in rrc_idle mode of operation).

According to this aspect of the invention, the proximity between two mobile communication devices may be detected by the first mobile communication device according to a network configuration. It is suggested to include in the configuration data geographic parameters ("location data") determined or predicted in terms of infrastructure. The configuration process itself will be discussed in more detail in the context of the third aspect of the invention described below.

With respect to geographic parameters, a location on the earth may be represented by latitude and longitude. Latitude (abbreviated as Lat, phi or phi) is the angle between the equatorial plane and a line emanating from the center of a reference ellipsoid that approximates the shape of the earth to account for the nature of the earth's dipolar flattening and equatorial bulge. The lines connecting points of the same latitude are called wefts, and the trajectories of the wefts on the earth surface are concentric circles and parallel to the equator. North is 90 ° north latitude; south pole is 90 ° south latitude. The 0 ° parallel line of latitude is designated as the equator and is the base plane of all geographic coordinate systems. The equator divides the world into a northern hemisphere and a southern hemisphere. Longitude (which may be abbreviated as Long, lambda or lambda) refers to the east or west angle between a reference meridian between two geographic poles and another meridian passing through any point. All warp threads are half of a great circle and are not parallel. They meet at both north and south poles. A line passing through the greenwich royalty astronomical station (in the vicinity of london, uk) was selected as the international zero longitude reference line, the primary meridian. The eastern part of the primary meridian is in the eastern hemisphere, and the western part is in the western hemisphere. The anti-primary meridian of greenwice is 180 degrees in both the western and eastern meridians.

Table 1 shows that the location of an example can be expressed in two different ways or formats. The second row of table 1 illustrates latitude and longitude in decimal value format. The third row illustrates the same longitude and latitude in degrees, minutes, seconds. Each data format can be easily translated or converted to another data format. In combination with latitude and longitude values, any location of any point on the earth's surface may be specified. They may be supplemented with an additional altitude value to specify a point above average sea level (not shown in table 1 for simplicity). The geographic parameters used in the present invention may consist of any combination of latitude, longitude and altitude in any format.

TABLE 1

	Decimal fraction	Degree-min-sec
			Latitude (phi)	North latitude 52.264667	52 DEG 15 '52.80' North
Longitude (lambda)	Dongjing 10.523776	10 DEG 31 '25.59' east

Further, in terms of geographic parameters, the distance between two mobile communication devices may be defined by a reference point and a maximum allowed distance. For example, if the first mobile communication device finds that it is approaching a given location (or entering an area surrounding a given reference point) by comparing output data from a Global Navigation Satellite System (GNSS) receiver or similar location determining module with its configured location information for the method of the invention, then a proximity detection event occurs. In this case, the first mobile communication device may begin sending paging indications to one or more second mobile communication devices according to its configuration, which the network considers to be in the vicinity of the first mobile communication device. Of course, in doing so, the first mobile communication device needs to take into account all other configuration parameters it receives in the configuration data set (e.g., related to timing requirements, resources to be used on the PC5 air interface, etc.).

A third aspect of the present invention is directed to configuring a first mobile communication device.

The present invention describes two configuration options for the innovative approach. In both options, a set of configuration data is transmitted from the network to the first mobile communication device in subframe n. The set of configuration data may refer to a subframe (n+x) that occurs at a later point in time (if x 1) or may refer to the same subframe (n) that it is in when received by the first mobile communication device (if x=0). Or the configuration data may also contain a pattern of subframes, and thus may refer to more than one subframe that will occur at a later point in time.

According to one embodiment of the invention, the configuration data set contains location information, such as geographical parameters (list), or cell IDs (list), and similar information (commonly referred to as "location data"). The geographic parameters may be determined or predicted in terms of infrastructure or read from a database.

According to another embodiment of the invention, the set of configuration data contains timing information, which may include relative time indications (e.g. "the configuration is applicable within three subframes from now on" or "the configuration is applicable within 3 milliseconds from now on"), and/or timing references (e.g. in the form of a base station identifier (list)), and the like. If UE1 and UE2 reside on different base stations in a heterogeneous network (HetNet) deployment (e.g., consisting of a macro base station layer and a small base station layer), the base station identifier (list) may help UE1 calculate the exact point in time to send the paging indication. By means of the base station identifier, UE1 can find out the Timing Advance (TA) of the base station that is suitable for providing cell coverage for UE2 (e.g. after random access to the cell). Since the frame timing of the cell serving UE1 may be different from the frame timing of the cell in which UE2 resides, the TA determined by performing random access on another cell may be used by UE1 to calculate the exact point in time to transmit the paging indication to UE 2. Details about such random access are contained in the first aspect described above (see description of fig. 7).

The first configuration option is shown in fig. 8.

The configuration data is transmitted from the network to the first mobile communication device at the physical layer (i.e., on the PDCCH) via Downlink Control Information (DCI) elements (see fig. 8). The DCI element may be an enhancement/modification to an existing DCI element or may be newly designed to support a configuration method.

The DCI may be addressed to one specific first mobile communication device (using a single RNTI) or a Group of first mobile communication devices (using a newly defined Group-RNTI). In fig. 8, subframe 1 is transmitted by an infrastructure side (base station). Subframe 2 represents the same subframe as received by the first mobile communication device. The "C" field in CCR indicates that configuration data is transmitted from the network to the first mobile communication device via the DCI element.

The second configuration option is shown in fig. 9.

Configuration data is transferred from the network to the first mobile communication device of the RRC layer through RRC signaling (see fig. 9). For this RRC signaling, the existing downlink RRC message may be enhanced/modified or an entirely new RRC message may be designed to support the configuration method. One type of RRC message is for all UEs within the coverage of a given radio cell (broadcast RRC signaling), while another type of RRC message is for a single UE (dedicated RRC signaling). The method of the present invention is not limited to either of these two types of RRC information. According to the invention, the network is free to choose whether to use broadcast RRC signaling or dedicated RRC signaling to communicate the set of configuration data to the one or more first mobile communication devices over the Uu air interface.

In fig. 9, subframe 1 is transmitted by an infrastructure side (base station). Subframe 2 represents the same subframe as received by the first mobile communication device. The "C" field in the SCR indicates that the configuration data is transmitted from the network to the first mobile communication device by means of (broadcast or dedicated) RRC signalling.

The signaling of the physical layer (option 1, according to fig. 8) is somewhat faster but less reliable (in terms of ciphering and error correction) than RRC signaling. Signaling at the RRC layer (option 2, according to fig. 9) allows for wider configuration data and provides more flexibility to construct the payload of the present invention. For our primary scenario, where the second mobile communication device is an internet of things device that needs to be awakened, configuration option 2 is preferred.

A fourth aspect of the present invention relates to the problem of paging over the PC5 air interface.

According to this aspect of the invention, the two separate information needed in the paging procedure are sent by two different entities. First, a Paging Indication (PI) is transmitted from UE1 to UE2, and then a Paging Message (PM) is transmitted from the base station to UE2. While the latter (i.e. PM) is always transmitted in the SCR of the downlink subframe, the PI transmission of UE1 may occur on the sidelink radio resources or downlink radio resources, which will be explained in the next section.

Fig. 10 depicts the case where UE1 uses sidelink resources to transmit PI over the PC5 air interface. The secondary link resources (with respect to frame timing and frequency allocation) are chosen in such a way that they are time and frequency-wise together with those downlink resources where UE2 normally expects the PDCCH transmitted from its serving base station to occur, i.e. if PM is transmitted in subframe (n+x), then PI must also arrive at UE2 in subframe (n+x). The remainder of the sidelink resource grid in subframe 1 (i.e., resources other than those used for the PI of the present invention) may or may not be left blank. Subframe 1 and subframe 2 contain PI. Subframe 1 is transmitted by UE1 and subframe 2 represents the reception of the same subframe by UE2. UE1 may choose to transmit this sidelink subframe in the portion of the resource grid that UE2 normally expects (from its base station) a downlink subframe to reach. Subframe 3 and subframe 4 contain PM. Subframe 3 is transmitted by the base station and subframe 4 represents the reception of the same subframe by UE2. As expected by UE2, PM is located in the SCR.

Fig. 11 depicts a case where UE1 transmits PI over the PC5 air interface using downlink resources. This means that UE1 mimics the base station functionality in this part of the operation. In one embodiment, the analog base station functionality may require UE1 to (at least) turn on the second TX chain for a limited period of time. The downlink resources (with respect to frame timing and frequency allocation) are chosen in such a way that they are together in time and frequency with those downlink resources that UE2 normally expects to appear from the PDCCH transmitted from its serving base station, i.e. if PM is transmitted in subframe (n+x), PI must also arrive at UE2 in subframe (n+x). In subframe 1, the remainder of the downlink resource grid (other than the resources for the PI of the present invention) may or may not be left blank.

Subframe 1 and subframe 2 contain PI. Subframe 1 is transmitted by UE1 and subframe 2 represents the reception of the same subframe by UE 2. UE1 may choose to transmit the downlink subframe in the portion of the resource grid that UE2 normally expects (from its base station) for the downlink subframe to arrive. Subframe 3 and subframe 4 contain PM. Subframe 3 is transmitted by the base station and subframe 4 represents the reception of the same subframe by UE 2. As expected by UE2, PM is located in the SCR.

In fig. 10 and 11, the subframe perceived by UE2 at the time point (n+x) is a superposition of subframe 1 (transmitted by UE 1) and subframe 3 (transmitted by the base station). This constituent "downlink subframe" contains both PI and PM in the CCR (e.g., PM in SCR) as expected by UE 2.

A fifth aspect of the present invention relates to fine resource coordination.

Fig. 10 and 11 also show the portion of CCR for subframe 3 labeled "B". This portion of the downlink resource grid is preferably left blank (i.e., unused) by the base station serving UE2 in order to avoid any resource collision between subframe 3 transmitted over the Uu air interface and subframe 1 transmitted over the PC5 air interface, according to one embodiment of the present invention. Without this clearance, interference may occur on various UEs in the vicinity of the two mobile communication devices UE1 and UE2, in particular on UE 2.

For example, the "B" portion of the CCR may include one or more Resource Elements (REs) or Resource Blocks (RBs) of the PDCCH allocated to subframe 3, in which paging indications (e.g., in the form of DCI, the Cyclic Redundancy Check (CRC) portion of which is scrambled by one paging-RNTI) are typically sent out.

A sixth aspect of the present invention relates to a timing relationship across subframes.

A sixth aspect relates to timing relationships that cross subframe boundaries. This means that unlike the current deployment, the control channel region transmitting PI and the shared channel region transmitting the subsequent PM no longer reside in the same subframe. Details of this are shown in fig. 12. In the previous figures, the amount of time between the reception of the paging configuration by UE1 (in subframe n) and the execution of the paging procedure in the relevant subframe (n+x) is indicated. In contrast, fig. 12 shows the length of time between the reception of the subframe (n+x) and the subframe (n+y), where x < y.

In this case, UE2 needs to know that PI and PM are not received in the same subframe. The offset may be part of a configuration procedure according to the third aspect of the invention.

Preferred aspects of the invention include:

(1) A method for a first mobile communication device to assist in paging a second mobile communication device;

in particular, the paging procedure includes at least one of:

Receiving a paging indication from a first mobile communication device over a device-to-device direct air interface; receiving a paging message from a base station;

Also, wherein the transmission of the paging indication is configurable by the base station, the paging indication being sent when at least one of the following criteria is met:

location requirements (the first mobile communication device has detected proximity to the second mobile communication device);

Time requirements (the first mobile communication device has detected a paging opportunity/reachability to the second mobile communication device).

And other requirements, wherein the novel paging procedure further comprises at least one of:

generating a location fix in the first mobile communication device;

Comparing, by the first mobile communication device, the location fix information with configuration data received from the base station;

Determining, by the first mobile communication device, a transmission time for transmitting the subframe to the second mobile communication device over the direct device-to-device air interface;

A paging indication is included by the first mobile communication device in a subframe transmission to the second mobile communication device.

Note that: the order of "position check" and "time check" is arbitrarily selected. The reverse can also be true.

Another aspect is wherein determining the transmission time further comprises at least one of:

Random access by a first mobile communication device to a base station serving a second mobile communication device;

The first mobile communication device receiving the timing advance value from a base station serving the second mobile communication device;

calculating, by a first mobile communication device, a timing offset between said first and second mobile communication devices from said timing advance value received by said base station serving the second mobile communication device;

Determining, by a first mobile communication device, a precise point in time for subframe alignment between the first and second mobile communication devices using the timing offset; and

A subframe is transmitted by the first mobile communication device to the second mobile communication device at the exact point in time.

The invention also provides a mobile communication device with means for implementing the paging procedure.

The present invention provides an infrastructure device with means for implementing a paging procedure.

Claims

1. A method of performing a paging action for a second user equipment device in a mobile communication system comprising the second user equipment device, a first user equipment device, and a first base station and a second base station, the method comprising:

transmitting a configuration message from the first base station to the first user equipment device to configure the first user equipment device to transmit a paging indication at a predetermined time in place of the first base station if it is determined that a geographic condition is satisfied;

Transmitting, by the first user equipment device, the paging indication to the second user equipment device, and

After the paging indication is sent, a paging message is sent from one of the first base station and the second base station to the second user equipment device.

2. The method of claim 1, wherein the geographic condition is that the second user equipment device is within a predetermined proximity of the first user equipment device.

3. The method of claim 1 or claim 2, wherein the first user equipment device determines whether the geographic condition is met by analyzing global navigation satellite system information.

4. The method of claim 1 or claim 2, wherein the paging indication is transmitted over a sidelink (sidelink) between user equipment devices.

5. The method of claim 1 or claim 2, wherein the paging indication is transmitted by the first user equipment device as a base station emulator.

6. The method according to claim 1 or claim 2, wherein the configuration message comprises location information and/or time information.

7. The method of claim 6, wherein the configuration message is transmitted to the first user equipment device through downlink control information.

8. The method of claim 6, wherein the configuration message is transmitted to the first user equipment device by radio resource control signaling.

9. The method of claim 1 or claim 2, wherein the first base station does not transmit in a portion of a downlink resource grid to be used by the first user equipment device to send the paging indication.

10. The method of claim 1 or claim 2, wherein the second user equipment device is informed of a time difference between one subframe received from the first user equipment device carrying the paging indication and one subframe received from the first or second base station carrying the paging message.

11. A method according to claim 1 or claim 2, wherein the first user equipment device determines its location, compares its determined location with configuration data received from the first base station, and determines a transmission time for transmitting the paging indication.

12. The method of claim 11, wherein to determine the transmission time, the first user equipment device performs random access for the second base station serving the second user equipment device, receives a timing advance parameter from the second base station, calculates a timing offset between the first user equipment device and the second user equipment device, determines a point in time of subframe alignment between the first and second user equipment devices using the timing offset, and transmits a subframe containing the paging indication at the point in time.

13. The method of claim 1 or claim 2, further comprising sending, by the first user equipment device, the paging indication to the second user equipment device.