RU2681368C1 - Improved distribution of resources for connection between devices (d2d) - Google Patents

Abstract

FIELD: radio engineering and communications.SUBSTANCE: invention relates to method of distributing radio resources to transmitting terminal for direct communication over a direct connection of a communication line. Transmitting terminal receives from the base station a broadcast system information packet that contains information on a temporary pool of radio resources of the transmission indicating radio resources for the transmission of the forward link transmission, and contains configuration information for the resource pool to limit the amount of time that a temporary radio resource pool can be used by the transmitting terminal.EFFECT: technical result consists in improving distribution of radio resources to transmitting terminal for direct communication over a direct connection of communication line.13 cl, 22 dwg, 5 tbl

Description

FIELD OF THE INVENTION

The present invention relates to methods for distributing radio resources to a transmitting terminal for transmitting with direct communication over a direct connection of a communication line with a receiving terminal. The present invention also provides a transmitting terminal and a base station for participating in the methods described herein.

BACKGROUND

Long Term Development (LTE)

Third-generation (3G) mobile systems based on WCDMA radio access technology are deployed on a large scale around the world. The first step in improving or developing this technology involves the introduction of High Speed Downlink Packet Access (HSDPA) and Advanced Uplink, also called High Speed Uplink Packet Access (HSUPA), which provide highly competitive radio access technology.

To be ready to further increase user demand and be competitive with new radio access technologies, 3GPP has introduced a new mobile communications system called Long-Term Development (LTE). LTE is designed to meet the needs of a mobile operator in the high-speed transmission of data and media streams, as well as in providing voice transmission with high bandwidth for the next decade. The ability to provide high data rates is the main quantitative indicator for LTE.

The Long Term Evolution (WI) Work Item Specification (LTE), called the UMTS Enhanced Universal Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN), is finalized as version 8 (Ver. 8 LTE). The LTE system is an efficient radio access and radio access network that provides full Internet Protocol (IP) -based functionality with low latency and low cost. In LTE, many scalable bandwidths are defined as 1.4, 3.0, 5.0, 10.0, 15.0 and 20.0 MHz in order to achieve flexible system deployment using a given spectrum. In the downlink, orthogonal frequency division multiplexing (OFDM) radio access has been adopted due to its inherent resistance to multipath interference (MPI) due to the low symbol rate, the use of cyclic prefix (SR) and its compatibility with different bandwidth arrangements . In the uplink, radio access based on frequency division multiple access and single-carrier transmission (SC-FDMA) was adopted, since coverage of large areas was considered more important than improving peak data rate given the limited transmission power of user equipment (UE) . Many packet radio access methods are used, including transmission methods based on the channel of a multi-channel input - multi-channel output and in ver. 8/9 LTE achieves a highly efficient control signaling structure.

LTE Architecture

The general architecture is shown in FIG. 1, and in more detail the architecture of the E-UTRAN is shown in FIG. 2. The E-UTRAN consists of an eNodeB providing end of user plane protocols (PDCP / RLC / MAC / PHY) and control plane (RRC) in the direction of the user equipment (UE). The eNodeB (eNB) hosts the following layers: physical (PHY), medium access control (MAC), radio link control (RLC) and packet data control protocol (PDCP), which include header compression and user plane encryption. It also provides a radio resource management (RRC) function corresponding to the control plane. It performs many functions, including radio resource management, connection control, scheduling, forced Quality of Service (QoS) negotiation of an uplink negotiated, cell information transmission, encryption / decryption of user plane and control data, and compression / decompression of user plane packet headers downstream / uplink communication. eNodeBs are interconnected through their X2 interface.

The eNodeBs are also connected via an S1 interface to an EPC (Evolved Packet Core), more specifically, to an MME (Mobility Management Node) via an S1-MME and to a Serving Gateway (SGW) via an S1-U. The S1 interface maintains a many-to-many relationship between the MME / serving gateways and various eNodeBs. SGW routes and transmits user data packets, while acting as a mobility binding for the user plane during handovers between the eNodeB and as a mobility binding between LTE and other 3GPP technologies (terminating the S4 interface and transferring traffic between 2G / 3G and GW PDN systems ) For the standby user equipment, the SGW terminates the downlink data path and starts paging when the downlink data arrives for the user equipment. It manages and stores user equipment contexts, for example, IP channel service parameters, information about internal network routing. It also replicates user traffic in the event of legitimate message interception.

MME is a key control node for the LTE access network. He is responsible for tracking and paging user equipment in standby mode, including retransmissions. He is involved in the activation / deactivation of the channel and is also responsible for the selection of SGW for the user equipment during the initial connection and during the transfer of service inside LTE, which involves the removal of the Core Network (CN) node. He is responsible for user authentication (through interaction with HSS). Layerless access (NAS) signaling ends in the MME and is also responsible for the generation and distribution of temporary user equipment identifiers. It checks the permission of the user equipment based on the carrier’s public land mobile network (PLMN) and enforces the roaming restrictions of the user equipment. MME is the termination point in the network for encrypting / combining transmitted information from alteration for NAS signaling and manages security keys. Legal signaling interception is also supported by MMEs. The MME also provides a control plane function for mobility between LTE and 2G / 3G access networks, with the S3 interface terminating in the MME from the SGSN. The MME also completes the S6a interface towards the home HSS for roaming user equipment.

LTE carrier structure

поднесущих, как показано также на фиг. 4.The carrier component of the downlink of the LTE 3GPP system is divided in the time-frequency domain into the so-called subframes. In LTE 3GPP, each subframe is divided into two downlink slots, as shown in FIG. 3, wherein the first downlink interval comprises a control channel region (PDCCH region) in the first OFDM symbols. Each subframe consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (version 8)), wherein each OFDM symbol spans the entire downlink component bandwidth. Thus, each of the OFDM symbols consists of a series of modulation symbols transmitted on the respective

subcarriers, as also shown in FIG. four.

последовательных символов OFDM во временной области (например, 7 символов OFDM) и

последовательных поднесущих в частотной области, как приведено в качестве примера на фиг. 4 (например, 12 поднесущих для несущей составляющей). В LTE 3GPP (версия 8) физический ресурсный блок состоит из

ресурсных элементов, соответствующих одному интервалу во временной области и 180 кГц в частотной области (дополнительные сведения о ресурсной сетке нисходящей линии связи см., например, в документе 3GPP TS 36.211, «Расширенный универсальный наземный радиодоступ (E-UTRA); Физические каналы и модуляция (версия 8)», раздел 6.2, доступном по адресу http://www.3gpp.org и включенном в настоящий документ путем ссылки).Based on a multi-carrier communication system, for example using OFDM, as, for example, used in 3GPP long-term development (LTE), the smallest unit of resources that can be assigned by the scheduler is one “resource block”. Physical Resource Block (PRB) is defined as

consecutive OFDM symbols in the time domain (e.g., 7 OFDM symbols) and

serial subcarriers in the frequency domain, as shown by way of example in FIG. 4 (e.g., 12 subcarriers for the carrier component). In LTE 3GPP (version 8), a physical resource block consists of

resource elements corresponding to one interval in the time domain and 180 kHz in the frequency domain (for more information on the downlink resource grid, see, for example, 3GPP TS 36.211, Enhanced Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (version 8) ”, Section 6.2, available at http://www.3gpp.org and incorporated herein by reference).

последовательным поднесущим, перекрывающим полный подкадр, называются «парой ресурсных блоков», или, что то же, «парой RB» или «парой PRB».One subframe consists of two slots, so there are 14 characters of the OFDM subframe when using the so-called “normal” cyclic prefix (CP) and 12 OFDM symbols in the subframe when using the so-called “extended” CP. For terminology hereinafter, time-frequency resources equivalent to the same

sequential subcarriers spanning the entire subframe are called a “resource block pair”, or, equivalently, an “RB pair” or a “PRB pair”.

The term “carrier component” refers to a combination of several resource blocks in the frequency domain. In future versions of LTE, the term “carrier component” is no longer used; instead, the term is changed to “cell”, which refers to a combination of downlink resources and, if necessary, uplink. The relationship between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information transmitted in the resources of the downlink.

Similar assumptions for the structure of the bearing component also apply to later versions.

LTE-A carrier aggregation to support wider bandwidth

The frequency spectrum decision for IMT-Advanced was made at the 2007 World Radiocommunication Conference (WRC-07). Although a decision has been made on the common frequency spectrum for IMT-Advanced, the actual available frequency range varies depending on each region or country. Meanwhile, after deciding on the basic principles of the available frequency spectrum in the Third Generation Partnership Project (3GPP), standardization of the radio interface began. At meeting No. 39 of the 3GPP TSG RAN, a description of the research element “Further Improvements for E-UTRA (LTE-Advanced)” was approved. The research element encompasses technology components to be considered for the development of E-UTRA, for example, to meet the requirements of IMT-Advanced.

The bandwidth that the LTE-Advanced system is capable of supporting is 100 MHz, while the LTE system can only support 20 MHz. Currently, the lack of radio spectrum has become a limiting factor in the development of wireless networks, and as a result it is difficult to find a spectral band that is wide enough for the LTE-Advanced system. Therefore, it is imperative to find a way to obtain a wider spectral band, moreover, a possible answer is the carrier aggregation function.

In carrier aggregation, two or more carrier components (carrier components) are aggregated in order to maintain wider transmission bands up to 100 MHz. Several cells in the LTE system are aggregated into one wider channel in the LTE-Advanced system, which is wide enough for 100 MHz even if these cells in LTE are in different frequency bands.

All bearing components can be made compatible with ver. 8/9 LTE, at least when the aggregated number of carrier components in the uplink and downlink are the same. Not all load-bearing components aggregated by user equipment may necessarily be compatible with ver. 8/9. To avoid basing user equipment ver. 8/9 on the carrier component, existing mechanisms may be used (e.g. prohibition).

A user equipment may simultaneously receive or transmit one or a plurality of carrier components (corresponding to a plurality of serving cells) depending on its capabilities. LTE User Equipment Ver. 10 with reception and / or transmission capabilities for carrier aggregation can simultaneously receive and / or transmit to a plurality of serving cells, while user equipment ver. 8/9 LTE can only receive and transmit in one serving cell, provided that the structure of the carrier component complies with the specifications of the ver. 8/9.

Carrier aggregation is supported for both adjacent and non-adjacent bearing components, with each carrier component being limited to a maximum of 110 Resource Blocks in the frequency domain using 3GPP numerical LTE (Version 8/9) data.

You can configure LTE-A (version 10) compatible 3GPP user equipment to aggregate a different number of carrier components originating from the same eNodeB (base station), and possibly other bands in the uplink and downlink. The number of carrier components of the downlink that can be configured depends on the possibility of aggregation in the downlink of the UE. In turn, the number of uplink carrier components that can be configured depends on the uplink aggregation capability of the UE. It may not be possible to configure a mobile terminal with more uplink carrier components than downlink carrier components.

In a typical TDD deployment, the number of carrier components and the band of each carrier component in the uplink and downlink are the same. Carrier components originating from the same eNodeB need not provide the same coverage.

The spacing between the center frequencies of adjacent aggregated carrier components is a multiple of 300 kHz. This is necessary for compatibility with the 3GPP LTE (Version 8/9) 100-KHz frequency raster and, at the same time, preliminary preservation of the orthogonality of the subcarriers at 15 kHz spacing. Depending on the aggregation scenario, n × 300 kHz spacing may be achieved by introducing a low number of unused subcarriers between adjacent carriers.

The nature of aggregation of multiple carriers is detected only to the MAC level. For both the uplink and the downlink, there is one HARQ entity required in the MAC for each aggregated carrier component. There is (in the absence of SU-MIMO for the uplink) no more than one transport block per carrier component. The transport block and its potential HARQ retransmissions must be mapped onto the same carrier component.

The Layer 2 structure with activated carrier aggregation is shown in FIG. 5 and FIG. 6 for the downlink and uplink, respectively.

When carrier aggregation is configured, the mobile terminal has only one RRC connection to the network. When establishing / re-establishing an RRC connection, one cell provides a secure input (one ECGI, one PCI and one ARFCN) and information about the mobility of the non-access layer (for example, TAI), similar to Ver. 8/9 LTE. After the RRC connection is established / re-established, the carrier component corresponding to this cell is called the downlink primary cell (PCell). There is always one and only one downlink PCell (DL PCell) and one uplink PCell (UL PCell) configured for each user equipment in a connected state. Within a configured set of carrier components, other cells are called secondary cells (SCell); wherein the SCell carriers are the secondary downlink carrier component (DL SCC) and the secondary uplink carrier component (UL SCC).

The configuration and reconfiguration, as well as the addition and exclusion of carriers, can be performed by RRC. Activation and deactivation are carried out through the control elements of the MAC. During handover within LTE, the RRC may also add, exclude, or reconfigure SCell for use in the target cell. When adding a new SCell, dedicated RRC signaling is used to send system information about SCell, moreover, the information is necessary for transmission / reception (similar to Ver. 8/9 for handover).

When configuring the user equipment with carrier aggregation, there is one pair of carrier components of the uplink and downlink, which is always active. The downlink carrier component of this pair may also be referred to as a DL anchor carrier. The same applies to the uplink.

When carrier aggregation is configured, user equipment can be scheduled for multiple carrier components at the same time, but no more than one random access procedure can be performed at any given time. Inter-carrier scheduling allows the PDCCH carrier to schedule resources for another carrier. To this end, a carrier component identification field called CIF is introduced in the respective DCI formats.

The relationship between the uplink and downlink carriers makes it possible to identify the uplink carrier for which resolution is applied in the absence of inter-carrier scheduling. The connection of the bearing components of the downlink with the bearing component of the uplink does not have to be one-to-one. In other words, more than one downlink carrier component may communicate with the same uplink carrier component. At the same time, the carrier component of the downlink can only communicate with one carrier component of the uplink.

RRC LTE States

LTE is based on only two main states: “RRC_IDLE” and “RRC_CONNECTED”.

In RRC_IDLE, the radio is not active, but the ID is assigned and monitored by the network. In particular, the mobile terminal at RRC_IDLE performs cell selection and reselection — in other words, it decides which cell to base on. The cell reselection process takes into account the priority of each applicable frequency of each applicable radio access technology (RAT), the quality of the radio link, and the state of the cell (i.e., whether the cell is blocked or reserved). The mobile terminal RRC_IDLE controls the paging channel to detect incoming calls and, in addition, receives system information. System information mainly consists of parameters by which the network (E-UTRAN) can control the process of (re) cell selection, as well as how the mobile terminal accesses the network. RRC defines the control signaling applicable to the mobile terminal in RRC_IDLE, namely, paging and system information. The behavior of the mobile terminal in RRC_IDLE is specified in more detail, for example, in document TS 36.304, chapter 4, "General understanding of the standby mode", incorporated herein by reference.

In RRC_CONNECTED, the mobile terminal has an active radio operation with contexts in the eNodeB. The E-UTRAN allocates radio resources to the mobile terminal to facilitate the transmission of (unicast) data over shared data channels. To support this operation, the mobile terminal monitors the associated control channel, which is used to indicate the dynamic allocation of shared transmission resources in time and frequency. The mobile terminal provides the network with reports on the status of its buffer and on the quality of the downlink, as well as measurement information about the neighboring network to allow E-UTRAN to select the most suitable cell for the mobile terminal. These measurement reports include cells using different frequencies or RATs. The UE also receives system information consisting mainly of information required to use the transmission channels. To extend the life of its battery, the UE in RRC_CONNECTED can be configured using a bursting cycle (DRX). RRC is a protocol by which an E-UTRAN controls the behavior of a UE in RRC_CONNECTED.

Various functions of the mobile terminal in the RRC protocol for connected mode and including it are described in 3GPP TS36.331, in Chapter 4, “Functions”, incorporated herein by reference.  Uplink Access Scheme for LTE

For uplink transmission, transmission by an energy-efficient user terminal is required to maximize coverage. Single-carrier transmission combined with FDMA with dynamic bandwidth allocation was selected as the extended UTRA uplink transmission scheme. The main reason for the preference for single-carrier transmission is the lower peak-to-average signal power-to-average ratio (PAPR) compared to multi-carrier (OFDMA) signals and the corresponding improved power amplifier efficiency and expected improved coverage (higher data rates for a given terminal peak power) ) During each time interval, node B assigns users a unique time-frequency resource for transmitting user data, thereby providing intra-cell orthogonality. Orthogonal uplink access promises increased spectral efficiency by eliminating intra-cell interference. The multipath interference is processed at the base station (node B) by introducing a cyclic prefix into the transmitted signal.

The basic physical resource used for data transmission consists of a frequency resource of size BW _grant for one time interval, for example, a 0.5 ms subframe onto which bits of encoded information are mapped. It should be noted that a subframe, also called a transmission time interval (TTI), is the smallest time interval for transmitting user data. However, it is possible to assign a frequency resource BW _grant for a longer period of time than one TTI to a user by concatenating subframes.

UL Planning Scheme for LTE

The uplink scheme allows both planned access, i.e., managed by the eNB, and competition-based access.

In the case of a planned UE access, a certain frequency resource is allocated for a certain time (i.e., a time-frequency resource) for data transmission on the uplink. However, some time-frequency resources may be allocated for competition-based access. Within these time-frequency resources, UEs may transmit without being first scheduled. One scenario in which the UE performs a competition-based access is, for example, random access, i.e., when the UE performs initial access to a cell or to request uplink resources.

For the planned access, the node B scheduler assigns the user a unique time-frequency resource for uplink data transmission. In particular, the scheduler determines:

- which (which) UE is allowed to transmit,

- what are the resources of the physical channel (frequency),

- transmission format (modulation code scheme (MCS)) to be used by the mobile terminal for transmission.

Distribution information is signaled to the UE by scheduling permission sent over the L1 / L2 control channel. For simplicity, in the future, this channel is called the uplink resolution channel. The scheduling grant message contains at least information about which part of the frequency band the UE is allowed to use, the validity period of the grant, and the transmission format that the UE should use for upcoming uplink transmission. The smallest validity period is one subframe. Additional information may also be included in the permission message depending on the selected scheme. Only “per UE” permissions are used to grant UL-SCH transmission rights (ie, there is no “per UE per RB” permissions). Therefore, the UE needs to distribute distributed resources among the radio channels in accordance with some rules. Unlike HSUPA, there is no choice of transmission format based on the UE. The eNB selects a transmission format based on some information, for example, reported scheduling information and QoS information, and the UE must follow the selected transmission format. In HSUPA, the Node B assigns the maximum uplink resource, and the UE selects the actual transmission format for data transmissions accordingly.

Since radio resource scheduling is the most important function in a shared channel access network to determine Quality of Service, there are a number of requirements that must be met by the UL scheduling scheme for LTE in order to enable effective QoS management.

- A lack of low priority services should be avoided.

- Clear QoS differentiation for radio channels / services should be supported by a scheduling scheme.

- UL reporting should allow detailed buffer reports (for example, for each radio channel or for each group of radio channels) to allow the eNB scheduler to identify for which radio channel / service data should be sent.

- It should be possible to create a clear differentiation of QoS between the services of different users.

- It should be possible to ensure a minimum transmission rate per radio channel.

As can be seen from the list above, one important aspect of the LTE scheduling scheme is to provide mechanisms by which an operator can control the partitioning of its aggregate cell capacity between radio channels of different QoS classes. The QoS class of the radio channel is identified by the QoS profile of the corresponding SAE channel, signaled from the AGW to the eNB, as described above. The operator can then distribute a certain amount of aggregate cell throughput to the aggregated traffic associated with the radio channels of a certain QoS class. The main purpose of using this class-based approach is to be able to differentiate packet processing based on the QoS class to which they belong.

Information Structure (Broadcast) System

In 3GPP terminology, information of a (broadcast) system is also denoted by BCCH information, i.e., it denotes information transmitted via a broadcast control channel (which is a logical channel) of a radio cell to which a UE is connected (active state) or attached (standby state).

Typically, system information includes an overhead information block (MIB) and several system information blocks (SIB). The MIB contains control information for each block of system information. The control information associated with the corresponding SIB may have the following structure. The corresponding control information associated with the SIB may indicate the position of the SIB in the transport channel (for example, the position in the time-frequency plane for OFDM radio access, i.e., specific resource blocks assigned to transmit the corresponding SIB) through which it is transmitted, relative to the total clock frequency. In addition, the SIB repeat period may be indicated. This retry period indicates the frequency with which the corresponding SIB is transmitted. The control information may also include a timer value for the timer-based update mechanism or, alternatively, a tag value for the tag-based SIB information update.

The table below shows an overview of the classification and types of system information blocks in a standard UMTS system as defined in 3GPP TS 25.331, Radio Resource Management (RRC), Version 12.2.0, Section 8.1.1, incorporated herein by links. System information is also defined for LTE systems, and information on this can be found in TS 36.331 c. 12.2.0 subclause 6.3.1, incorporated herein by reference.

As explained in more detail in the following sections, device-to-device communication (D2D) technology is expected to be implemented for Ver.12 LTE. Among other things, 3GPP standardization is currently in the process of defining Type 18 SystemInformationBlock to contain some information related to direct communication and ProSe detection. The following definition of SIB18 is taken from the currently discussed request to modify r2-143565 for TS 36.331, covering the current agreements regarding ProSe, the decision on which, however, has not yet been finalized, and therefore it is subject to consideration only as an example.

SystemInformationBlockType18 Information Element

Field descriptions SystemInformationBlockType18 commIdleTxPool
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in RRC_IDLE. discInterFreqList
Indicates adjacent frequencies at which a direct detection notification is provided. discIdleTxPool
Indicates the resources by which the UE is allowed to send direct discovery notifications when located in RRC_IDLE.

As can be seen from the above system information, the commIdleTxPool field, including the commSA-TxResourcePoolCommon subfields, indicates shared resources from which any UE receiving SIB18 and, nonetheless, in a standby state can use (on a competitive basis). In other words, the network operator can usually determine the radio resources for all UEs, which, however, can only be used when the UE is still in standby. As will be presented below, these radio resources defined by commIdleTxPool are classified as Mode 2 resources for offline use by different UEs.

Buffer Status Reporting

The buffer status reporting procedure is used to provide the serving eNB with information about the amount of data available for transmission in the UL buffers to the UE. The RRC controls BSR reporting by configuring two periodicBSR-Timer and retxBSR-Timer timers, and — for each logical channel — by optionally signaling a logicalChannelGroup that allocates LCG logical channels. Further information on buffer status reporting can be found in 3GPP TS 36.321 Subclause 5.4.5, incorporated herein by reference.

Proximity services (ProSe) between devices (D2D) LTE

Proximity applications and services are a recent social and technological trend. These areas include services related to commercial services and public safety, which could be of interest to operators and users. The introduction of Proximity Services (ProSe) capabilities in LTE would enable the 3GPP industry to serve this emerging market, while at the same time serving the urgent needs of several public safety communities that are actively committed to LTE.

Inter-Device Communication (D2D) is a technology component for Ver. 12 LTE. Inter-device communication technology (D2D) allows D2D as the basis for a cellular network to increase spectral efficiency. For example, if the cellular network is LTE, all physical channels transmitting data use SC-FDMA for D2D signaling.

D2D to LTE Communications

D2D communications in LTE focuses on two areas: discovery and communications.

In D2D communications, the UEs transmit data signals to each other over a forward link using cellular resources instead of being transmitted through a base station (BS). D2D users communicate directly while remaining under BS control, i.e., at least while in the eNB coverage area. Therefore, D2D can improve system performance by reusing cellular resources.

It is assumed that D2D operates in the uplink LTE spectrum (in the case of FDD) or in the uplink subframes of the cell providing coverage (in the case of TDD, except when outside the coverage area). In addition, D2D transmission / reception does not use full duplex on a given carrier. From the point of view of a separate UE, on a given carrier, the reception of a D2D signal and LTE uplink transmission does not use full duplex, i.e., simultaneous reception of a D2D signal and LTE uplink transmission are not possible.

In D2D communication, when one particular UE1 plays the role of a transmission (transmitting user equipment or a transmitting terminal), UE1 sends data, and another UE2 (receiving user equipment) receives them. UE1 and UE2 can exchange their transmit and receive roles. A transmission from UE1 may be received by one or more UEs like UE2.

For user plane protocols, the following is part of the agreement in terms of D2D communications (see also 3GPP TS 36.843 vers. 12.0.0 section 9.2.2, incorporated herein by reference).

1. PDCP:

- Broadcast data 1: M D2D (i.e., IP packets) should be processed as normal user plane data.

- Header compaction / decompression in PDCP is applicable for 1: M D2D broadcast.

- U mode is used to compress headers in PDCP for D2D broadcast mode for public safety;

- RLC:

- UM RLC is used for 1: M D2D broadcast.

- Segmentation and reassembly is provided by RLC UM over L2.

- The receiving UE must support at least one RLC UM for each transmitting peer UE.

- The RLC UM receiver object does not have to be configured before receiving the first RLC UM data block.

- So far, no need has been identified for RLC AM or RLC TM for D2D communications for transmitting user plane data.

- MAS:

- No feedback is assumed for broadcast 1: M D2D.

- The receiving UE needs to know the identifier (ID) of the source to identify the RLC object of the UM receiver.

- The MAC header contains the identifier of the target L2, which allows to exclude packets at the MAC level.

- The target ID L2 may be a broadcast, multicast, or single-point address.

- Group / single-point L2: the L2 target identifier contained in the MAC header would allow the received RLC UM PDU to be discarded before it is sent to the RLC receiver object.

- Broadcast L2: the receiving UE would process all received RLC PDUs from all transmitters and would aim to reassemble and transmit the IP packets to the upper layers.

- The MAC subheading contains various LCIDs (to distinguish between multiple logical elements).

- At the very least, multiplexing / demultiplexing, priority processing, and padding are appropriate for D2D.

Distribution of radio resources

From the point of view of the transmitting UE, the activated Proximity UE service (activated ProSe UE) can operate in two modes for resource allocation:

Mode 1 refers to the eNB's planned resource allocation, in which the UE requests transmission resources from the eNB (or the Version 10 transit node), and the eNodeB (or Version 10 transit node), in turn, schedules the exact resources used by the UE to transmit direct data and direct control information (e.g., planning assignment). The UE must be RRC_CONNECTED in order to transmit data. In particular, the UE sends a scheduling request (D-SR or random access) to the eNB following the buffer status report (BSR) in the usual way (see also the next section, “Transmission procedure for D2D communication”). Based on the BSR, the eNB can determine that the UE has data for transmission with direct ProSe communication and can estimate the resources needed for transmission.

On the other hand, Mode 2 refers to the selection of resources of a stand-alone UE, in which the UE independently selects resources (time and frequency) from resource pools for transmitting direct data and direct control information. One resource pool is defined, for example, by the SIB18 content (as presented in the previous section), namely, by the commIdleTxPool field, and this particular resource pool is broadcast in the cell and then publicly available for all UEs in the cell is still in the RRC_Idle state. Alternatively, or in addition, another resource pool can be defined by the eNB and specifically allocated by the UE, namely, by using the commTxResourcePool field. Although not yet finalized, the corresponding ProSe information element is currently standardized for TS 36.331 in accordance with change request r2-143565. In this regard, the following definition should be considered as an example only:

ProseCommConfig Information Element

Field descriptions Prosecommconfig commSA-RxResourcePoolDedicated
Indicates the resource pool that the UE should monitor in order to receive scheduling assignments for Prose communications. commTxResourcePool
If enabled, the UE is allowed to use the specified resources under normal or exceptional conditions, depending on commTxPoolUse. If it is not enabled, or when the conditions for use are not met, the UE that wants to start a direct communication involving transmission must request an E-UTRAN to assign resources for each individual transmission, as specified in 36.321 [6]. commSA-TxResourcePoolDedicated
Indicates TBC. commData-TxResourcePoolDedicated
Indicates TBC.

This ProSeCommConfig information element may be part of the network response transmitted by the eNB in response to a corresponding request by the UE that involves D2D communication. For example, as illustrated in FIG. 16, the UE may transmit an indication of interest in D2D communications to the eNB in case the UE wishes to perform D2D communications. The D2D communication response (for example, as part of the RRCCommunicationReconfiguration) may, for example, include the above ProseCommConfig information element.

In addition, pre-configured radio resources available to a UE that is outside the coverage area of the eNB cell for D2D SA or data transmission can also be classified as Mode 2 resources.

Which resource allocation mode the UE will use is configured by the eNB, as explained above. In addition, which resource allocation mode the UE will use for transmitting D2D data may also depend on the RRC state, i.e., RRC_IDLE or RRC_CONNECTED, and the coverage state of the UE, i.e., in the coverage area, outside the coverage area . A UE is considered to be in a coverage area if it has a serving cell (i.e., the UE is RRC_CONNECTED or is based on a cell in RRC_IDLE).

In accordance with the agreements reached so far (see request for changes to TS 36.300 in R2-143672, section on resource allocation), the following rules apply to the UE regarding the mode of resource allocation:

- If the UE is outside the coverage area, it may use Mode 2;

- If the UE is in range, it may use Mode 1 if the eNB configures it accordingly;

- If the UE is in range, it may use Mode 2 if the eNB configures it accordingly;

- When there are no exceptional conditions, the UE may switch from Mode 1 to Mode 2 or vice versa if it is configured by the eNB to do this. If the UE is in range, it uses only the mode specified by the eNB configuration, unless one of the exceptional cases occurs;

- the UE considers itself to be in exceptional conditions, for example, when performing T311 or T301;

- When an exceptional case occurs, the UE is allowed to temporarily use Mode 2, even if it is configured to use Mode 1.

Located in the coverage area of the E-UTRA cell, the UE performs direct ProSe transmission on the UL carrier only over the resources assigned to this cell, even if the resources of this carrier are pre-configured, for example, in a UICC (universal integrated circuit card).

For UEs located in RRC_IDLE, the eNB may choose one of the following options:

- The eNB may provide a transmission resource pool in Mode 2 in the SIB. UEs that are allowed for direct ProSe communication use these resources for direct ProSe communication in RRC_IDLE;

- The eNB may indicate to the SIB that it supports D2D, but does not provide resources for direct ProSe communication. UEs must be included in RRC_CONNECTED to transmit ProSe direct communications.

For UE in RRC_CONNECTED:

- The UE at RRC_CONNECTED, which is allowed to transmit with direct communication ProSe, indicates to the eNB that it wishes to transmit with direct communication ProSe when it needs to transmit with direct communication ProSe;

- the eNB checks whether the UE is allowed in RRC_CONNECTED for direct ProSe transmission using the UE context received from the MME;

- the eNB may configure the UE in RRC_CONNECTED by dedicated signaling with a Mode 2 resource allocation transmission resource pool, which can be used without limitation when the UE is RRC_CONNECTED. Alternatively, the eNB can configure the UE in RRC_CONNECTED by dedicated signaling with a Mode 2 resource allocation transmission resource pool, which is allowed to be used by the UE only in exceptional cases, and in other cases rely on Mode 1.

Such behavior of the UEs regarding resource allocation is illustrated in a simplified form in accordance with the state diagrams in FIG. 7 and 8. FIG. 7 relates to the case in which the UE is in the RRC_IDLE state, and delimits being in the coverage area and outside the coverage area. It should be noted that a UE that is outside the coverage area and in RRC_IDLE can use the resource allocation in Mode 2. At the time defined for the UE in RRC_IDLE, there are no exceptional cases. On the other hand, FIG. 8 relates to a case in which the UEs are in the RRC_CONNECTED state, and delimits being in the coverage area and outside the coverage area. It is clear that the connected UE, which is in an exceptional case, can use the resource allocation in Mode 2.

FIG. 9 illustrates the use of transmission / reception resources for an upper layer system (LTE) and a lower layer (D2D).

Basically, an eNodeB controls whether a UE can apply a transmission in Mode 1 or Mode 2. Once the UE knows its resources in which it can transmit (or receive) a D2D message, in the state of the art it uses the appropriate resources only for the corresponding transmission / reception. For example, in FIG. 9, D2D subframes will only be used to receive or transmit D2D signals. Since the UE as a D2D device can operate in half-duplex mode, it can either receive or transmit D2D signals at any time. Similarly, the other subframes illustrated in FIG. 9 can be used to transmit and / or receive LTE (upper layer).

Transfer Procedure for D2D Communication

The D2D data transfer procedure differs depending on the mode of resource allocation. As described above for mode 1, the eNB explicitly schedules resources to schedule and transmit D2D data after a corresponding request from the UE. In particular, the UE may be informed by the eNB that D2D communication is generally permitted, but that Mode 2 resources (i.e., resource pool) are not provided; this can be done, for example, by exchanging an indication of interest in the D2D communication and the corresponding response to the D2D communication performed by the UE, as illustrated in FIG. 16, moreover, the corresponding example of the ProseCommConfig information element mentioned above will not include commTxREsourcePool, which means that a UE that wishes to start a direct communication involving transmission must request the E-UTRAN to assign resources to each individual transmission. Therefore, in this case, the UE must request resources for each individual transmission, and below the various steps of the request / grant procedure are listed as an example for this Mode 1 resource allocation:

- Step 1: the UE sends an SR (scheduling request) to the eNB on the PUCCH;

- Step 2: the eNB provides the UL resource (so that the UE sends the BSR) over the PDCCH encrypted with C-RNTI;

- Step 3: the UE sends a D2D BSR indicating the status of the buffer, on PUSCH;

- Step 4: The eNB provides a D2D resource (for the UE to send data) over a PDCCH encrypted with D2D-RNTI.

- Step 5: D2D Tx UE transmits SA / D2D data in accordance with the resolution obtained in step 4.

A scheduling assignment (SA) is a compact (low payload) message containing control information, for example, a pointer (s) to time-frequency resources for corresponding D2D data transmissions. The SA content is basically consistent with the permission adopted in Step 4 above. The details of the D2D permission and SA content have not yet been established, but as an operational assumption for the SA content, the following arrangements have been made:

- The frequency resource is indicated in the Type 0 UL resource allocation ver. 8 (5-13 bits depending on the system bandwidth)

- 1-bit frequency switching indicator (according to Ver. 8)

- It should be noted that some reinterpretation of the indexing must be defined in such a way that the switch does not use different PRBs outside the configured resource pool for mode 2.

- Only single-cluster resource allocations are allowed

- it follows from the above that if there are gaps in the resource pool in the frequency domain, the allocation of resources will not close the gap

- There is no RV indicator in SA

RV pattern for data: {0, 2, 3, 1}.

On the other hand, for the allocation of resources in mode 2, the above steps 1-4 are generally not needed, and the UE autonomously selects resources for transmitting SA and D2D data from the resource pool (s) configured and provided by the eNB.

FIG. 10 illustrates, by way of example, the transmission of scheduling assignment and D2D data for two UEs, UE-A and UE-B, wherein resources for sending scheduling assignments are periodic, and resources used for transmitting D2D data are indicated by the corresponding scheduling assignment.

Resource Pool for Planning and D2D Data Assignment

The resource pool for Planning Assignment (SA) and D2D data, when the UE is out of coverage, can be configured as follows:

- The resource pool used to receive the SA is pre-configured.

- The resource pool used for SA transfer is preconfigured.

- The resource pool used to receive D2D data is pre-configured.

- The resource pool used to transmit D2D data is pre-configured.

The resource pool for Schedule Assignment (SA) and D2D data, when the UE is in the coverage area, can be configured as follows:

- The resource pool used to receive the SA is configured by the eNB through the RRC in dedicated or broadcast signaling.

- The resource pool used for SA transmission is configured by the eNB via RRC if mode 2 resource allocation is used.

- The SA resource pool used for transmission is unknown to the UE if mode 1 resource allocation is used.

- the eNB schedules a specific resource (s) for use in transmitting a scheduling assignment if a mode 1 resource allocation is used. The particular resource assigned by the eNB is within the resource pool for receiving the Scheduling Assignment that is provided to the UE.

UE coverage states for D2D

As mentioned above (see, for example, FIGS. 7 and 8), the resource allocation method for D2D communication depends - in addition to the RRC state, i.e., RRC_IDLE and RRC_CONNECTED, also on the coverage state of the UE, i.e., in coverage area, outside the coverage area. A UE is considered to be in a coverage area if it has a serving cell (i.e., the UE is RRC_CONNECTED or is based on a cell in RRC_IDLE).

The two coating conditions mentioned so far, i.e., in the coverage area (IC) and outside the coverage area (OOC), are further divided into substates for D2D. In FIG. 11 shows four different states with which UE D2D can be associated and which can be briefly described as follows:

- State 1 : UE1 has coverage in uplink and downlink. In this state, the network manages each D2D session. In addition, the network configures whether UE1 should use mode 1 or mode 2 resource allocation.

- State 2 : UE2 has downlink coverage but does not have uplink, i.e. only has DL coverage. The network broadcasts (based on competition) a pool of resources. In this state, the transmitting UE selects resources used for the SA and data from a resource pool configurable by the network; in this state, resource allocation is only possible in accordance with mode 2 for D2D communication.

- State 3 : Since UE3 has no coverage in the uplink and downlink, UE3, strictly speaking, is already considered to be outside the coverage area (OOS). However, UE3 is in the coverage area of some UEs that themselves (e.g., UE1) are in the coverage area of the cell, i.e., said UEs may also be referred to as CP relay UEs, therefore, the UE region in state 3 in FIG. 11 may be referred to as a coverage area of a relay UE CP. UEs in this state 3 are also called UEs in state 3 of the OOS. In this state, the UEs receive some cell-specific information that is sent by the eNB (SIB) and forwarded to the UEs by relaying the CP UEs in the cell coverage area via PD2DSCH to different UEs in the OOS state 3. A network-driven (competition-based) resource pool is signaled by the PD2DSCH.

- State 4 : UE4 is outside the coverage area and does not receive PD2DSCH from other UEs that are in the coverage area of the cell. In this state, which is also called an OOS of state 4, the transmitting UE selects resources used for data transmission from a pre-configured resource pool.

The reason for distinguishing between OOS of state 3 and OOS of state 4 is mainly the elimination of potentially strong interference between D2D transmissions from devices outside the coverage area and standard transmissions on E-UTRA. Typically, UEs supporting D2D have a pre-configured resource pool (s) for transmitting various SAs and D2D data for use when out of range. If said out-of-band UEs are transmitted in said pre-configured resource pools near cell boundaries, then interference between D2D transmissions and standard transmissions in the coverage area can adversely affect communication within the cell. If UEs activated by D2D, within the coverage area, redirected the configuration of the D2D resource pool to the specified devices located outside the coverage area near the cell boundary, then UEs located outside the coverage area can limit their transmission to resources specified by eNode B and, therefore, minimize interference in standard gears in the coverage area. So, RAN1 introduced a mechanism in which UEs in the coverage area redirect resource pool information and other configurations related to D2D to these devices immediately outside the coverage area (state UE 3).

The D2D Physical Synchronization Channel (PD2DSCH) is used to transmit this information about the D2D resource pools located in the coverage area to the UE in the network proximity so that the resource pools within the network proximity match. However, the detailed content of PD2DSCH is not yet installed.

D2D Detection

ProSe Direct Detection (proximity proximity service) is defined as the procedure used by a ProSe-activated UE to detect another (other) ProSe-activated UEs near itself using direct E-UTRA radio signals via the PC5 interface. FIG. 12 schematically illustrates a PC5 interface for direct detection between devices.

The upper level processes the permission for the notification and control of the detection information. To this end, the UEs must exchange predefined signals referred to as detection signals. By periodically checking the detection signals, the UE maintains a list of proximity UEs to establish a link if necessary. Detection signals must be reliably detected, even in low SNR conditions. To allow periodic transmission of detection signals, resources for detection signals must be assigned.

There are two types of direct detection of ProSe: open and limited. Open is the case where there is no explicit permission that is required from the detected UE, while limited detection is only possible if there is explicit permission from the detected UE.

Direct ProSe discovery can be an autonomous service activator in a detecting UE that activates a detecting UE to use information from the detected UE for some applications. For example, the information transmitted during direct detection of ProSe can be “find a taxi nearby”, “find a cafe for me”, “find my nearest police station”, etc. Through direct detection, the ProSe UE detection can obtain the necessary information. In addition, depending on the information received, direct ProSe detection can be used for subsequent actions in the communication system, such as initiating direct ProSe detection.

ProSe Direct Detection Models

ProSe Direct Detection is based on several detection models. An overview is given below. ProSe direct detection models are further defined in 3GPP TS 23.303 V12.1.0, section 5.3, which is incorporated herein by reference.

Model A (“I'm here)

Model A is also indicated as “I am here” because the notifying UE broadcasts information about itself, such as ProSe application identifiers or ProSe UE identifiers in the discovery message, thereby identifying itself and notifying other parties to the communication system that it is available.

In accordance with Model A, two roles for ProSe-activated UEs that are involved in direct ProSe detection are defined. The UE activated by ProSe may function as a notification UE and a monitoring UE. the reporting UE notifies of some information that may be used by various nearby UEs that have permission to detect. The monitoring UE monitors some information of interest in the vicinity of the reporting UEs.

In this model A, the reporting UE broadcasts detection messages at predetermined detection intervals, and the monitoring UEs that are interested in these messages read them and process them.

Model B (“who is it?” / “Are you listening?”)

This model defines two roles for the different ProSe-activated UEs that are involved in direct ProSe discovery:

- UE Detector: A UE that transmits a request containing some information about what is interesting to the detector;

- Detected UE: A UE that receives a request message may respond with some information related to the request of the detector.

Model B is equivalent to “who's there” / “you are listening,” since the UE detector transmits information about other UEs from which it would like to receive responses. The information transmitted may, for example, be about the ProSe application identifier corresponding to the group. Group members may respond to said transmitted information.

According to this Model B, two roles are defined for the different ProSe-activated UEs that participate in direct ProSe discovery: the UE detector and the detected UE. The UE detector transmits a request containing some information about what is interesting to the detector. On the other hand, the detected UE receives the request message and may respond with some information related to the request of the UE detector.

The discovery information content is transparent to an access layer (AS) that does not know the content of the discovery information. Thus, no distinction is made in the access layer between the different ProSe direct detection models and the ProSe direct detection types. The ProSe protocol provides only the valid discovery information to the AS for notification.

The UE may participate in the notification and monitoring of the discovery information in both the RRC_IDLE state and the RRC_CONNECTED state for each eNB configuration. The UE notifies and monitors its discovery information depending on half-duplex restrictions.

Types of detection

FIG. 13 illustrates a diagram showing IDLE and CONNECTED modes when receiving discovery resources in D2D communication and in relation to a resource allocation procedure.

D2D communication can either be a managed network when the operator controls the switch between direct transmissions (D2D) and traditional cellular communication lines, or the direct communication lines can be controlled by devices without operator control. D2D allows you to combine infrastructure mode and special communications.

As a rule, device discovery must be done periodically. In addition, D2D devices use the detection message signaling protocol to perform device discovery. For example, a D2D activated UE may transmit its discovery message, and another D2D activated UE may receive this discovery message and may use this information to establish a communication link. An advantage of a hybrid network is that if D2D devices are also within range of a network infrastructure, network objects like eNBs can further facilitate the transmission or configuration of discovery messages. The coordination / control performed by the eNB when transmitting or configuring discovery messages is also important to ensure that the transmission of D2D messages does not interfere with cellular traffic controlled by the eNB. In addition, even if some of the devices are outside the network coverage range, those in the device’s coverage area may contribute to a special detection protocol.

At least the following two types of detection procedures are defined to determine the terminology used hereinafter.

- Type 1 : a resource allocation procedure in which resources for notifying discovery information are allocated in a non-specific manner to the UE, further characterized in that:

- The eNB provides one (multiple) UEs with a resource pool configuration used to notify discovery information. The configuration can be signaled in the SIB.

- The UE autonomously selects the radio resource (s) from the indicated resource pool and notifies the discovery information.

- The UE may notify discovery information of a randomly selected discovery resource during each discovery period.

- Type 2 : a resource allocation procedure in which resources for reporting discovery information are allocated in a UE-specific manner, further characterized in that:

- The UE at RRC_CONNECTED may request the resource (s) for notification of discovery information from the eNB through the RRC. The eNB assigns the resource (s) by RRC.

- Resources are assigned within the resource pool, which is configured in different UEs for monitoring.

Resources — in accordance with a Type 2 procedure — for example, are allocated semi-permanently to transmit a detection signal.

In the case where the UEs are in RRC_IDLE mode, the eNB may choose one of the following options:

- The eNB may provide a Type 1 resource pool for notification of discovery information in the SIB. UEs that are allowed direct ProSe discovery use these resources to notify discovery information in RRC_IDLE.

- The eNB may indicate to the SIB that it supports D2D, but does not provide resources for reporting discovery information. UEs must enter RRC Connected in order to request D2D resources for notification of discovery information.

For various UEs in the RRC_CONNECTED state, the UE that is allowed to perform the ProSe direct detection notification indicates to the eNB that it wants to perform the D2D detection notification. The eNB then checks to see if the direct detection of the ProSe is allowed by the UE using the UE context received from the MME. The eNB may configure the UE to use a Type 1 resource pool or allocated Type 2 resources to notify discovery information through dedicated RRC signaling (or not use the resource). The resources allocated by the eNB are valid until a) the eNB disconfigures the resource (s) with RRC or b) the UE enters the IDLE.

The receiving UEs in RRC_IDLE and RRC_CONNECTED monitor the discovery resource pools of both Type 1 and Type 2 as they are resolved. The eNB provides a resource pool configuration used to monitor discovery information in the SIB. A SIB may contain discovery resources, also used for notification in neighboring cells.

Radio Protocol Architecture

FIG. 14 schematically illustrates a radio protocol (AS) protocol stack for direct ProSe detection.

The AS layer interfaces with the upper layer (ProSe protocol). Accordingly, the MAC layer receives detection information from the upper layer (ProSe Protocol). In this regard, the IP layer is not used to transmit discovery information. In addition, the AS layer performs a scheduling function, according to which the MAC layer determines the radio resource used to notify of the detection information received from the upper layer. In addition, the AS layer has the function of generating a discovery PDU, according to which the MAC layer creates a MAC PDU containing the discovery information, and sends the MAC PDU to the physical layer for transmission in a designated radio resource. The MAC header is not added.

In the UE, the RRC protocol reports discovery resource pools to the MAC. RRC also reports a dedicated type 2 resource for transmission to the MAC. The MAC header is not required. The MAC header for detection does not contain any fields based on which filtering at Level 2 could be performed. Filtering the detection message at the MAC level does not seem to save processing or energy compared to performing filtering at higher levels based on the identifier ProSe UE or ProSe Application Identifier. The MAC receiver forwards all received discovery messages to higher layers. The MAC will transmit to the upper layers only correctly received messages.

It is assumed below that L1 (PHY) indicates to the MAC whether the detection messages were received correctly. In addition, it is assumed that the Upper Levels guarantee the delivery of only valid discovery information to the access layer.

D2D Sync

The main task of synchronization is to allow receivers to receive a time and frequency reference signal. Such a reference signal can be used for at least two purposes: 1) alignment of the receiver window and frequency correction when detecting D2D channels, and 2) alignment of synchronization and transmitter parameters when transmitting D2D channels. To date, the following channels have been defined for synchronization in 3GPP:

- D2DSS - D2D sync signal

- PD2DSCH - physical synchronization channel D2D

- PD2DSS - primary D2D clock signal

- SD2DSS - secondary synchronization signal D2D

In addition, the following synchronization terminology has been agreed upon by 3GPP and will be used as an example in the rest of the application.

- D2D sync source: a node that at least transmits a D2D sync signal. The D2D clock source can typically be an eNB or a D2D UE.

- D2D sync signal: a signal from which the UE can receive clock and frequency synchronization.

D2D synchronization can be seen as a procedure that is similar to searching for cells in LTE. To enable both NW control and efficient synchronization for partial / external coverage scenarios, the following procedures for synchronizing the receiver and transmitter are currently under discussion within 3GPP.

Receiver sync

The ProSe-activated UE regularly searches for LTE cells (in accordance with LTE mobility procedures) and D2DSS / PD2DSCH transmitted by different synchronization (SS) UEs.

If any suitable cell is found, the UE is based on it and follows cell synchronization (in accordance with standard LTE procedures).

If any suitable D2DSS / PD2DSCH detected by different SS UEs is detected, the UE synchronizes its receiver with all incoming D2DSS / PD2DSCHs (depending on the capabilities of the UEs) and monitors incoming connections (scheduling assignments) to them. It should be noted that the D2DSS transmitted by the D2D clock source, which is an eNodeB, must be PSS / SSS (primary and secondary clock signals) Ver. 8. D2D clock sources, which are eNodeBs, have higher priority than D2D clock sources, which are UEs.

Transmitter synchronization

The ProSe-activated UE regularly searches for LTE cells (in accordance with LTE mobility procedures) and D2DSS / PD2DSCH transmitted by different SS UEs.

If any suitable cell is found, the UE is based on it and cell synchronization follows for transmitting D2D signals. In this case, the network may configure the UE to transmit D2DSS / PD2DSCH after cell synchronization.

If no suitable cell is found, the UE checks if any of the incoming D2DSS / PD2DSCH can be transmitted further (i.e., the maximum number of transit sections has not been reached), then (a) if the incoming D2DSS / PD2DSCH, which can be transmitted further , found, the UE adapts the synchronization of its transmitter to it and transmits D2DSS / PD2DSCH in accordance with this; or (b) if an incoming D2DSS / PD2DSCH, which can be transmitted further, is NOT found, the UE acts as an independent clock source and transmits D2DSS / PD2DSCH in accordance with any internal synchronization reference signal.

Further details about the synchronization procedure for D2D can be found in TS 36.843 V12.0.1, clause 7, incorporated herein by reference.

Cell Selection and RRC Connection Establishment

FIG. 15 illustrates in a simplified and exemplary prior art messaging between a UE and an eNB for cell selection and establishment of an RRC connection. The cell selection in step 2 is based, for example, on 3GPP TS 36.304, for example, section 5.2.3 of v12.1.0, incorporated herein by reference. A UE that is not based on any WAN cell (wide area network such as LTE) is considered to be out of range. Cell based may be based on the criteria / cell selection process, as defined in Section 5.2.3 in 3GPP TS 36.304-v 12.1.0. Therefore, before the completion of stage 2, the UE is generally considered to be outside the coverage area (OOS). Once the cell selection is successful and the UE is based (on a suitable cell or on an acceptable cell), it is in an RRC idle state. The UE continues to be in the RRC idle state until step 7, i.e., until it receives the RRCConnectionSetup message from the network, after which it changes state to the connected RRC.

SUMMARY OF THE INVENTION

In one non-limiting and illustrative embodiment, an improved method for allocating radio resources to a transmitting terminal for transmitting with direct communication over a direct connection of a communication line, reducing the problems discussed above, is provided. In the independent claims, one non-limiting and illustrative embodiment is proposed. Preferred embodiments are to be included in the dependent claims.

In accordance with the first aspect, for direct transmission, the network operator determines an additional (temporary) transmission radio resource pool - additional to the pending transmission radio resource pool, already defined in the prior art. Although the pending transmission radio resource pool of the prior art is limited to pending terminals, the additional transmission radio resource pool in accordance with the first aspect, although independent of the pending or connected state of the terminal, is configured such that the amount of time in the duration of which the temporary pool of transmission radio resources can be used by the transmitting terminal is limited. Therefore, the base station broadcasts in its cell system information containing information about said temporary transmission radio resource pool and corresponding configuration information. As in the case of standby transmission of a prior art radio resource pool, the temporary transmission radio resource pool in accordance with the first aspect indicates radio resources that can be used by those transmitting terminals that receive a broadcast system information packet for direct transmission to the receiving terminal directly connection line.

Different implementations of this first aspect differ in how the configuration information reaches the time limit for using this additional resource pool, or include additional requirements that the terminal must (at least try) to establish a radio connection with the base station when the terminal must use once such resources of the temporary pool of transmission radio resources.

By using this additional resource pool, it is possible to let the terminals in the cell not experience interruptions when establishing a radio connection with the base station.

Accordingly, in one general aspect, the methods described herein provide a method for distributing radio resources to a transmitting terminal for transmitting with direct communication over a direct connection of a communication line to a receiving terminal in a communication system. This method comprises the following steps performed by a transmitting terminal: receiving from a base station a broadcast system information packet that contains information on a temporary transmission radio resource pool indicating radio resources that can be used by those transmitting terminals that receive a broadcast system information packet for transmitting with direct communication to the receiving terminal via a direct connection of the communication line, and which contains configuration information for the temporary radio pool transmission resources, moreover, configuration information limits the amount of time during which a temporary pool of transmission radio resources can be used by the transmitting terminal. An appropriate terminal and base station are proposed for participating in this method.

In accordance with a second aspect, a pre-configured transmission radio resource pool is made available to terminals that are within the coverage area of a base station cell. Such a pre-configured pool of radio transmission resources is already known in the prior art for use in situations outside the coverage area, the second aspect extends its use also to situations in the coverage area of the terminals. By “pre-configured” in this context, it is understood that the pre-configured pool of transmission radio resources is known to the terminals even without receiving any system information from the radio access; for example, using information in the USIM card of a mobile phone or by signaling the highest level from the core network.

Similar to the first aspect, various implementations of the second aspect include the option of limiting the amount of time that such a pre-configured transmission radio resource pool can be used for terminals while in a cell coverage area, which can be done in various ways. Other implementations of the second aspect require that the terminal must (at least try) to establish a radio connection with the base station when the terminal must once use such resources of a pre-configured transmission radio resource pool.

Accordingly, in one general aspect, the techniques described herein provide a transmitting terminal for transmitting with direct communication over a direct connection of a communication line to a receiving terminal in a communication system. The transmitting terminal is pre-configured using a pre-configured transmission radio resource pool indicating radio resources that can be used by the transmitting terminal to transmit directly to the receiving terminal via a direct link, and the pre-configured transmission radio resource can be used when the transmitting terminal is in coverage area of the cell base station.

Additional benefits and advantages of the described embodiments will be apparent from the description and drawings. Benefits and / or advantages may individually be provided by various embodiments and features of the description and drawings, and not all of them need to be provided to obtain one or more of them.

These general and specific aspects can be implemented using a system, method and computer program, as well as any combination of systems, methods and computer programs.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments are described below in more detail with reference to the accompanying drawings.

FIG. one shows the illustrative architecture of the LTE 3GPP system, FIG. 2 shows an illustrative overview of the general E-UTRAN architecture in LTE 3GPP, FIG. 3 shows exemplary downlink carrier subframe boundaries, as defined for LTE 3GPP (Version 8/9), FIG. four shows an exemplary downlink resource grid of the downlink interval, as defined for LTE 3GPP (Version 8/9), FIG. 5 and 6 shows the structure of Layer 2 LTE-A 3GPP (Version 10) with activated carrier aggregation for the downlink and uplink, respectively, FIG. 7 and 8 give an overview of the mode (s) of resource allocation and transitions between resource allocation modes available to the terminal when in RRC_Idle, RRC_Connected, in the coverage area and outside the coverage area of the cell, FIG. 9 illustrates the use of transmission / reception resources for upper layer systems (LTE) and lower layer (D2D), FIG. 10 illustrates the transmission of scheduling assignment and D2D data for two UEs, FIG. eleven illustrates coverage in relation to four different states with which a UE D2D may be associated, FIG. 12 schematically illustrates a PC 5 interface for direct detection between devices, FIG. 13 illustrates a diagram showing the standby mode and connected mode when receiving discovery resources in D2D communication, FIG. fourteen schematically illustrates a radio protocol stack for direct detection of ProSe, FIG. fifteen illustrates an exemplary prior art messaging between a UE and an eNodeB for cell selection and establishment of an RRC connection, FIG. 16 illustrates the exchange of an indication of an indication of interest in a D2D communication and a corresponding response to a D2D communication, FIG. 17 illustrates an illustrative movement of a UE at a cell boundary, FIG. eighteen is a continuation of FIG. 15, illustrating, by way of example, the prior art messaging for cell selection, establishing an RRC connection, indicating UE-A interest in D2D communications, and requesting dedicated radio resources for transmitting D2D data and additionally indicating various time periods, FIG. 19 illustrates the messaging for the procedure for establishing a failed RRC connection, FIG. twenty illustrates periods when D2D data transmission is not possible for the UE, FIG. 21, 22 illustrate how the UE can apply T-RPT patterns to subframes for mode 1 of the corresponding resources of mode 2.

DETAILED DESCRIPTION OF THE INVENTION

It should be noted that the embodiments can preferably be used, for example, in a mobile communication system such as LTE-A (Version 10/11/12) 3GPP communication systems, as described above in the "Level of Technology" section, but the embodiments are not limited to use in these specific illustrative communication networks.

A mobile station, or a mobile node , or a user terminal is a physical object in a communication network. One node can have several functional objects. A functional object refers to a software or hardware module that implements and / or offers a pre-installed set of functions to other functional objects of a node or network. Nodes can have one or more interfaces that connect the node to a communication medium or an environment through which nodes can communicate. Similarly, a network entity may have a logical interface connecting a functional entity to a communication medium or medium through which it can communicate with other functional entities or corresponding nodes.

A “transmitting terminal” used in the claims and application refers to a user terminal as a transmitter. A “receiving terminal," on the contrary, refers to a user feed terminal as a receiver. The adjective “transmitting” and “receiving” is intended only to explain the temporary action / role.

The “direct-link transmission” used in the claims and application, by way of example, refers to communication between devices (D2D) currently being discussed for LTE version 12. The term “direct connection of a communication line” , respectively, as an example, refers to a connection or a communication channel through a PC5 interface that directly connects two D2D user terminals, which allows you to exchange data directly without using a network. In other words, a communication channel is established between two user equipments in a communication system that are close enough for direct data exchange, thereby bypassing the eNodeB (base station).

The term "procedure for establishing a radio connection" , used in the claims and application, can be understood as including or not including a random access procedure. Accordingly, initiating a radio connection establishment procedure can be understood as equivalent to transmitting a random access procedure preamble or equivalent to transmitting an RRC connection request message. Accordingly, in the context of LTE 3GPP, the radio connection establishment procedure may be a random access procedure following the RRC connection establishment procedure.

The term "allocated radio resources" used in the claims and application refers to radio resources specially assigned by a base station (eNode B) to a particular terminal. The allocated radio resources themselves can be either a mode 1 or a mode 2 resource, as discussed in the prior art section. This term is considered as a contrast to “common radio resources” , which can be widely used by terminals in a cell; for example, a transmission radio resource pool defined by system information (eg, SIB18) is broadcast in a cell, and therefore, the same radio resources are available for use by terminals receiving system information.

By the expression “initiate a radio connection establishment procedure” and similar expressions, it should be understood that a terminal is required to establish a radio connection with a base station, however, taking into account that a radio connection establishment procedure may not take place. In other words, although the terminal is required to try to establish a radio connection, the terminal may only be able to initiate an appropriate procedure for establishing a radio connection, but may not be able to continue the procedure for establishing a radio connection for successful establishment of a radio connection. In this regard, this expression should be considered as making this requirement to initiate the procedure for establishing a radio connection independent of the outcome, i.e., success (for example, receiving an RRC connection establishment message) or failure (for example, receiving an RRC connection reject message) establishing a radio connection.

By the expression “a pool of transmission radio resources that can be used” (and similar expressions) used in the claims and application, it should be understood in the broad sense that resources should not, but can be selected from a pool of transmission radio resources and used by the terminal if the terminal I would like to complete a direct link transfer (for example, scheduling assignments or direct link data). Accordingly, the expression about the used transmission radio resource pool (and similar expressions) should be understood in the broad sense that the terminal actually intends to carry out the direct communication transmission and selects suitable resources from the transmission radio resource pool and performs the said transmission with direct communication on the mentioned selected resources.

The term "in the coverage area" used in the claims and application, it should be understood in the broad sense that the terminal is considered to be in the coverage area if it has successfully selected a cell, regardless of whether the terminal is in the standby state or connected state. Cell selection criteria are defined in TS 36.304. All UEs located in the coverage area can receive signaling from the network either using broadcast messages (in the idle state and in the connected state), or using allocated (i.e., one-to-one between the UE and the network) messages in the connected state. For example, a UE is considered to be in a coverage area if it has a serving cell (i.e., the UE is RRC_Connected or based on a cell in RRC_Idle). The expression “outside the coverage area” should be understood in reverse.

The term "pre-configured" used in the claims and application, it should be understood in the broad sense that the corresponding resources from the resource pool are known to the terminals even without receiving any information from the radio access; i.e., a pre-configured pool of radio resources is available regardless of the cells and broadcast packets of system information in them.

The term "radio resources" , as used in the claims and the application, should be understood in a broad sense as referring to physical radio resources, such as time-frequency resources.

As explained in the prior art section, the UE may use various resources to directly communicate the D2D with another UE depending on its state and the configuration of the eNB. The inventors have identified many problems and disadvantages of the currently proposed implementation of direct communication, i.e., D2D 3GPP communication. The following various scenarios and problems are present and will be explained with reference to FIG. 18. FIG. 18, which is a continuation of FIG. 15 further illustrates a UE indicating an interest in D2D communication, and a request by the UE for allocated radio resources for transmitting D2D data, as well as various time periods 0, 1, 2, A, B, C, and D. Although in FIG. 18 is not shown, the UE may have preconfigured Mode 2 resources when it is outside the cell coverage area for receiving / transmitting SA and D2D data, as discussed in the prior art section.

The eNB may decide that in its network mode 2 resource allocation is not possible when the UE is waiting for the RRC. For the purpose of explanation, networks of this type are denoted by Type A networks. In particular, in Type A networks, the UE sees in SIB18 that D2D is allowed, but since there are no shared mode 2 resources broadcast to it (for example, a resource pool in accordance with mode 2) , it must first establish an RRC connection (see FIG. 15). Then, after it is properly configured for D2D (for example, using an indication of interest in the D2D link and the corresponding response to the D2D link; see FIG. 16), it may have access to Mode 2 resources for transmission (depending on how the UE is configured by the eNB corresponding to the D2D communication response message). If the response to the D2D connection no longer provides usable resources for D2D communication, for example, in the form of a dedicated mode 2 resource pool, the UE may need to explicitly request D2D related resources using dedicated signaling (scheduling request, report on buffer status), as described above in the prior art section (see D2D communication in steps 1-5 in the Transmission Procedure section), which takes longer (see period C).

Moreover, period D, as shown in FIG. 18 is a delay in sending the first D2D after receiving the corresponding D2D grant. Despite the fact that it can be considered negligible, perhaps this is not so, as the calculations of the inventors have shown; period D, taken by itself, can be about 300-400 ms depending on the configuration of the resources, such as the frequency of the BITMAP resource pool for each SA and the data, their offset (say, relative to SFN0), the exact distributed T-RPT (transmission pattern temporary resource), etc.

Therefore, the UE cannot communicate D2D during the full period D shown in FIG. 18, or even for periods C and D, if the response to D2D communication from the eNB, although providing D2D, does not provide the Mode 2 resources allocated by the UE (in which case the UE must specifically request resource permission for a specific D2D transmission).

Type A networks allow the network operator complete control over the use of resources, since he will know how many UEs are performing D2D, and he can share resources between using D2D and LTE. However, the UE in such a Type A network is unable to perform any idle D2D communications. In addition, even after the transition to the state of the connected RRC, the UE must send a message indicating the interest in D2D communication and at least wait for an explicit network response to receive D2D communication resources and, in addition, the time before the actual data transfer can take place communication (period C and / or period D). This delay can easily add up to 2 seconds or more. Since in Ver. 12 D2D communication is mainly aimed at public safety cases, even a 2-second delay / interruption is unacceptable, especially for the VoIP / Speech / Dialog class of service. This is especially true for UEs at the cell boundary that can move inward or outward between positions outside the coverage area and in the coverage area; see in FIG. 17 illustrates a UE that moves at the edge of a cell.

This problem is somewhat reduced in another type of network in which the deployment of networks using eNB provides for D2D Mode 2 common communication resources to be used in the RRC idle state; such a network can be designated as an example by type B. In such type B networks, the UE will start D2D communication using such mode 2 standby resources after receiving SIB18 (containing the corresponding mode 2 standby resource configuration, for example, commIdleTxPool) and, therefore, earlier than in type A networks; thus, these UEs can transmit D2D data for a short time before they again encounter an interrupt in periods B, C, and D. Therefore, although D2D communication is not possible in period 0, UE can communicate D2D during period A. .

However, in type B networks, UE D2D communications are also prevented from occurring at certain times, causing undesired delays and / or interruptions. The UE may continue to use pending Mode 2 resources for as long as it remains in the RRC idle state; Pending Mode 2 resources of the prior art from SIB 18 can only be used in the RRC idle state. However, when the UE establishes an RRC connection (regardless of the reasons; for example, based on the WAN, for example, for Internet access), and thus changes the RCC to the connected state (see step 7 in Fig. 15), it can no longer use these resources of the mode 2 resource pool defined by SIB18 to continue or initiate D2D communication, i.e., according to step 7 of FIG. 15. In this case, in order to resume the previously started D2D communication or start a new D2D communication, the UE must at least send a message indicating the interest in the D2D communication and wait for an explicit network response to receive D2D mode 2 communication resources (or even wait longer if necessary an explicit request for resource resolution for a particular D2D transmission, as discussed above with respect to steps 1-5 of the transmission procedure for D2D communication). This leads to a delay and / or interruption of communication; The UE cannot communicate D2D in periods B, C (and D).

In FIG. 20 shows the various periods introduced in FIG. 18, in the form of blocks and the difference between the periods when transmission in D2D communication is not possible for the UE, for networks of type A and type B is shown.

FIG. 19 is similar to FIG. 18, but illustrates the failed RRC connection establishment. As is clear from this, after initiating the establishment of the RRC connection, it fails (for example, because the RRC connection is rejected by the eNB; there may be other reasons, such as cell reselection or T300 expiration). The UE remains in the RRC idle state anyway. In Type A networks, such situations are particularly unfavorable, since the UE will be completely unable to communicate D2D while in the idle state. On the other hand, for type B networks, D2D communication is possible after receiving SIB 18, which includes configuring a pending Mode 2 resource; i.e., during A and beyond.

One explicit solution for Type B networks (which is also easy to implement) is to enable the use of pending Mode 2 resources (commIdleTxPool) also by terminals in the RRC connected state; at least, while the eNodeBs are assigned to the terminals, dedicated resources that can be used for direct communication (see period B + C (+ D) in FIG. 18).

The following first and second illustrative embodiments are intended by the inventors to reduce the problems explained.

Several embodiments are explained in detail below. The implementation of some of them is contemplated within the broad specification defined in 3GPP standards and partially explained in this section of the prior art, with specific main features being explained below in relation to various embodiments. It should be noted that the embodiments can preferably be used, for example, in a mobile communication system such as the LTE-A (Version 10/11/12) 3GPP communication system described in the prior art section above, but the embodiments are not limited thereto. use in these specific examples of communication networks.

The explanations should not be understood as limiting the scope of the invention, but merely as an example of embodiments for a better understanding of the present invention. One of ordinary skill in the art will understand that the general principles of the present invention set forth in the claims can be applied to various scenarios in ways that are not explicitly described herein. Accordingly, the following scenarios, intended to explain various embodiments, do not limit the invention as such.

First Embodiment

The first set of embodiments is explained below. To simplify illustrating the principles of the first embodiment, several assumptions have been made; however, it should be noted that these assumptions should not be interpreted as limiting the scope of the present application, generally defined by the claims.

In accordance with the first aspect, an additional pool of transmission resources for direct transmission is determined by the network operator, moreover, this additional pool of resources is in many respects different from the pending pool of transmission resources, already known from the prior art. As explained in the prior art section, at the discretion of the network operator, information on the transmission radio resource pool can be broadcast by the base station in its cell in such a way that the terminals receiving said broadcast system information packet can autonomously use the resources from said transmission radio resource pool if if they want to communicate directly with another terminal. The transmission radio resource pool of the prior art (referred to as the convenience of using the waiting transmission radio resource pool) can be used by the terminal when it is in the standby state, but not when its state changes to connected, which causes some of the problems mentioned above.

On the other hand, the additional transmission radio resource pool introduced in accordance with this first aspect (and called for the convenience of using a temporary transmission radio resource pool) is used only temporarily (i.e., for a limited amount of time), but regardless of whether whether the terminal is in a standby state or in a connected state. The network operator is able to control the amount of time during which this temporary pool of transmission radio resources can be used, using the corresponding additional indication (configuration information) in the broadcast system information packet. The limitation of the use of said temporary pool of radio resources for transmission over time can be implemented in several different ways, some of which will be explained as examples below, but are similar in that the time during which said temporary resources can be used is limited and can be controlled by the base station (i.e., network operator).

Network operators may be reluctant to make the pending pool of transmission radio resources publicly available to terminals through a broadcast system information packet, but rather prefer to assign specific dedicated resource pools to specific terminals or even just specific dedicated physical resources to each terminal to support full control their radio resources (or at least as much control as possible). Therefore, the network operator may not want the terminals in its cell to autonomously use the pending transmission radio resource pool of the prior art, for example, since the terminal can use the resources from this pending transmission radio resource pool almost endlessly (for as long as the terminal remains idle ) or since the network does not know how many UEs these D2D idle resources actually use, because it does not know about the number of such UEs (standby UEs at s is unknown and known only at the level of the tracking area which is significantly larger than the cell level); this does not allow the network to conclude: the mentioned standby D2D resources are too small (that is, a lot of conflicts when using D2D resources) or too much (that is, unnecessary eating up of other LTE resources). An additional temporary pool of transmission radio resources, on the other hand, allows the network operator to accurately determine the physical resources that can be used for a (more or less) configurable amount of time. Of course, there is a direct benefit here that the terminals can access resources for direct communication as soon as the terminals receive and process the corresponding broadcast system information packet with information about the temporary transmission radio resource pool, while the network operator can flexibly control the time during which such resources are typically provided to terminals in their cell. Since the number / number of UEs establishing an RRC connection will be significantly limited by the total number of idle UEs in a cell, the additional temporary transmission radio resource pool can be significantly more efficient / smaller in comparison with the prior art transmission radio resource pool (mode 2), broadcast to SIB18. In addition, an additional temporary transmission radio resource pool is particularly useful for terminals located in cells that will not actually provide such an awaiting transmission radio resource pool. But it is also useful for terminals in cells of a different type, which actually broadcast the pending pool of transmission radio resources, since in this case the resources for transmission with direct communication are also available when the terminal is already in a connected state, but the base station has not yet assigned it resources for use in direct communication, or he has not yet actually transferred D2D communication data.

Thus, by providing a temporary transmission resource pool of the first aspect in the broadcast system information packet of the cell, instead of or in addition to the waiting transmission resource pool of the prior art, delay or interruption of direct communication for terminals is reduced or almost eliminated, while giving the network operator as much control as possible resources. Depending on the particular implementation, in type A network cells (i.e., in addition to the pending pool of transmission radio resources in the system information), the terminals can use the resources from the temporary transmission pool of radio transmission resources discussed above after their reception, i.e., during period A , period B, period C and period D, as shown in FIG. 18. In cells of type B networks, terminals may use resources from a temporary transmission radio resource pool during periods B + C + D.

Additional implementations of the first aspect relate to how configuration information can limit the amount of time that a temporary transmit radio resource pool can be used by transmitting terminals in a cell. For example, a broadcast system information packet may directly indicate the required amount of time, for example, 10 ms, 100 ms, 2000 ms for a temporary transmission radio resource pool. Then, depending on the specific implementation, this indicated amount of time will be interpreted by the terminal in that the temporary pool of transmission radio resources can be used for a given specific time after, for example, receiving a broadcast system information packet. Alternatively, instead of starting the timer when the terminal receives a broadcast packet of system information, the timer can start when the transmitting terminal begins to use the temporary transmit radio resource pool (for example, by transmitting a scheduling assignment with direct communication to another terminal). In any case, there is a specific advantage in that such a configuration is independent of the procedure for establishing a radio connection and its outcome and, therefore, is predictable for a base station.

Alternatively, or in addition to directly indicating the amount of time, the time during which a temporary pool of transmission radio resources can be used can be limited “indirectly” by specifying specific conditions / events that prevent the terminal from subsequently using these resources. For example, a broadcast system information packet may include an instruction associated with a temporary transmission radio resource pool that the terminal wishing to use these resources should also try to establish a radio connection with the base station to avoid the terminal being in a standby state with infinite use of such resources. In this case, the terminal, for example, is only allowed to use the resources from the said temporary pool of transmission radio resources until a connection is established and the base station assigns allocated radio resources to the terminal, which is then used instead for a possible transmission with direct communication (see the period A + B + C in Fig. 18); or, if the connection cannot be established or rejected, until the terminal is informed of this failure to establish (see period A in Fig. 19); or the base station at this moment, although establishing a connection with the terminal, may not allow the terminal to transmit with direct communication (see period A + B in Fig. 18). Moreover, taking into account the long time it may take for the terminal to actually use the allocated radio resource assigned by the base station to the terminal, an additional alternative can extend the time during which the temporary pool of radio resources can be used until the moment the terminal (after establishing the radio connection with the base station and receiving from the base station dedicated radio resources for transmission with direct communication) will actually transmit with direct communication SA and and these data using the allocated radio resources assigned to the terminal by the base station (see. The period of A + B + C + D in FIG. 18).

The actual instructions for establishing a connection may, for example, indicate a specific amount of time within which the terminal needs to (at least) start establishing a connection (starting, for example, immediately after receiving a broadcast packet of system information or after starting to use a temporary pool of transmission radio resources). Another option is that the terminal is even required to initiate a connection before it is allowed to use radio resources from the temporary pool of transmission radio resources for direct communication. In this case, for example, it can be understood that the terminal begins to establish a connection with the base station by transmitting the preamble of the random access procedure.

In addition, for the first aspect, just as in the case of the pending transmission radio resource pool of the prior art, the temporary transmission radio resource pool can distinguish between resources available for transmission with a direct scheduling assignment link and resources available for transmission with a direct connection of direct scheduling data to another terminal over a direct connection. In this way, the cell can provide various resources to be used for transmitting scheduling assignments and data.

Above, several different implementations of the first aspect are considered. Below, the principles underlying the first aspect and their implementation are applied as an example to an LTE system (such as the system described in the prior art section).

In particular, the current 3GPP standardization suggests that the use of SIB18 contains some information related to direct communication and ProSe detection. Therefore, the information about the temporary transmission radio resource pool and its configuration information, as described above, can form part of this SIBType 18. Of course, it should be noted that for the purpose of this aspect, any other type of system information block can be used to transmit this information. In addition, in the particular selected example, the field in the system information block for transmitting information about the temporary pool of transmission and configuration radio resources is called ʺcommTxPoolTempʺ. Once again, it should be noted that for the purpose of this aspect, any other field name can be selected, or information about the temporary transmission radio resource pool can be inserted into another field from the corresponding configuration information. The same applies to names and formats selected for specific variables commSA-TxResourcePoolCommonTemp, commData-TxResourcePoolCommonTemp.

Accordingly, the following definition of an information element of type 18 of a system information block is taken for example only.

SystemInformationBlockType18 Information Element

Field descriptions SystemInformationBlockType18 commIdleTxPool
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in RRC_IDLE. discInterFreqList
Indicates adjacent frequencies at which a direct detection notification is provided. discIdleTxPool
Indicates the resources by which the UE is allowed to send direct discovery notifications when located in RRC_IDLE. commTxPoolTemp
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in RRC_IDLE, but it can only use these resources until allowedTime.

Important changes to this example of an information element of type 18 of the system information block for the first aspect with respect to the prior art are made in bold and underlined for ease of identification. As can be seen from this, in this particular example, the configuration information is implemented as the ʺallowedTimeʺ variable using examples of time values equal to 100 ms, 200 ms, etc., as shown above, thereby directly limiting the amount of time. Of course, the specific time values, as well as the number of time values that are configurable, should be considered as an example only; if necessary, any other time values and the number of configurable time values can be selected. By reading the value indicated by the ʺallowedTimeʺ variable, the terminal can determine how long the temporary transmission radio resource pool can be used after receiving a broadcast system information packet (or after the terminal starts using resources from the temporary transmission radio resource pool for direct communication); the corresponding timer can be set, started and monitored by the UE.

As an additional alternative, below is another example for defining SIB18. As in the example definition above, any names given to variables, as well as specific values given to variables, can only be considered as examples.

SystemInformationBlockType18 Information Element

Field descriptions SystemInformationBlockType18 commIdleTxPool
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in RRC_IDLE. discInterFreqList
Indicates adjacent frequencies at which a direct detection notification is provided. discIdleTxPool
Indicates the resources by which the UE is allowed to send direct discovery notifications when located in RRC_IDLE. commTxPoolTemp
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in the RRC_IDLE, but it should also subsequently or even earlier initiate the RRC connection establishment procedure, i.e., initiate access to the PRACH. timeToInitiateRRCConnEst
The time during which the UE must start the RRC connection establishment procedure, i.e., initiate access to the PRACH. ms01 means 1 ms, ms05 means 5 ms, etc. A value of 'alreadyInitiated' indicates that the UE may use commTxPoolTemp  only after initiating the RRC connection establishment procedure, for example, after initiating access to the PRACH.

Important changes to this example of an information element of type 18 of the system information block for the first aspect with respect to the prior art are made in bold and underlined for ease of identification. As you can see from here, the timeToInitiateRRCConnEst configuration variable is introduced to indirectly limit the use of the temporary transmit radio resource pool (i.e., commTxPoolTemp) based on various exit conditions, as explained below. By using this configuration variable timeToInitiateRRCConnEst UE, an instruction is issued to try to establish an RRC connection with an eNB for an illustrative time of 1 or 5 ms, etc., as shown above. Depending on the different behavior of the UE, the UE may, for example, be allowed to use the resources of the temporary pool of radio transmission resources until an RRC connection is established and the eNB assigns allocated radio resources to the terminal; or until the UE realizes that the RRC connection establishment has failed; or until the UE is informed by the eNB that it is not allowed to carry out direct communication in the cell; or until the direct SA or data is actually implemented using the allocated resources assigned to the UE by the eNB.

It should also be noted that this new commTxPoolTemp field is optional in SIB18, thereby giving control to the network operator to decide whether or not to broadcast the same cell. As a result of this, since the commIdleTxPool field (already defined in the prior art) is also optional, the network operator (via eNB) may optionally not configure the commIdleTxPool and commTxPoolTemp fields, or configure one or both of them.

Of course, a combination of the above definitions of SIB 18 is also possible, allowing a configuration in which the commTxPoolTemp field contains the variables ʺallowedTimeʺ and ʺtimeToInitiateRRCConnEst ".

Second Embodiment

The second aspect of the invention also solves the aforementioned fundamental problem (s) of the prior art, but in a different way. Instead of defining an additional transmission radio resource pool in the broadcast system information packet, as was done for the first aspect, this second aspect is based on the concept of using a pre-configured transmission radio resource pool for possible direct communication not only when the terminal is outside the cell coverage area (as currently defined in the prior art), but also when the terminal is in a cell coverage area. Pre-configured in this context should be distinguished from those "configured" resources that are configured by the broadcast system information packet from the base station. In other words, pre-configured resources, for example, are known to the terminals (and base stations) even without receiving any information from the radio access, i.e., regardless of the cells and the system information broadcast in them. In this regard, pre-configured radio resources in the prior art are already used by UEs that are outside the coverage area of the cell, that is, they have not received any broadcast packet of system information from the base station of any cell.

For example, a pre-configured pool of radio transmission resources can be determined by the network operator and be hardcoded into a regular sim / USIM card, which can be inserted and used in most ordinary mobile phones. Alternatively, higher-level signaling may be used to provide the terminal with the necessary information on such a pre-configured transmission radio resource pool; for example, from a backbone network using an Internet protocol or a layer protocol without access.

By using resources from a pre-configured pool of transmission radio resources, while also in the cell coverage area, the terminal can transmit with direct communication, regardless of whether it receives a broadcast system information packet, whether the broadcast system information packet includes resource pool information , whether the radio connection is established, the state the terminal is in (waiting or connected), etc. Thus, the terminal is not blocked, is not delayed or is not interrupted in relation to transmission with direct communication. Therefore, and in contrast to the first embodiment, in accordance with the second aspect, the terminals can also transmit with direct communication in period 0; in addition to periods A, B, C and D.

One option is to reconfigure a preconfigured pool of transmission radio resources already defined in the prior art for terminals outside the coverage area with the possibility of applying also to terminals that are in the coverage area of a base station cell.

On the other hand, an alternative would be to configure a new pre-configured transmission radio resource pool located in the coverage area, in addition to such a pre-configured transmission radio resource pool already defined in the prior art for terminals outside the coverage area, and the pre-configured coverage area in the coverage area the transmission radio resource pool is applicable to terminals that are in the coverage area but cannot be used i with terminals still outside the coverage area of the cell of the base station. In this case, both the pre-configured transmission radio resource pool outside the coverage area and the pre-configured transmission radio resource pool in accordance with the second aspect can be stored on the sim / USIM card, or alternatively can be detected by higher level signaling as mentioned above.

In yet another refinement of the second aspect, the network operator should have some control over whether this pre-configured transmission radio resource pool (even if it is pre-configured for a particular terminal) is actually used in its cell. For example, a network operator may decide that in its cell these resources from a pre-configured pool of transmission radio resources will not be available to the terminals. For these purposes, the broadcast system information packet should be appropriately indicated whether the terminals located in the cell coverage area are allowed to use it or not.

One simple opportunity for this indication is a single-bit flag in the system information, a single-bit value indicating validity, and another bit value indicating that the use of a pre-configured transmission radio resource pool is not permitted for terminals within the cell coverage area.

Alternatively, the system information may optionally include configuration information for a pre-configured transmission radio resource pool such that, in the absence of configuration information, the terminal realizes that the pre-configured transmission radio resource pool should not be used. On the other hand, when the configuration information for a pre-configured transmission radio resource pool is present in the system information and therefore received by the terminal connected to the cell, the terminal understands that it can continue to use the pre-configured transmission radio resource pool for direct communications, but in The add-on applies the configuration information mentioned for its use.

Configuration information is subject to change. For example, in accordance with the improvements for the second aspect, it is also advisable to limit the use of the aforementioned pre-configured transmission radio resource pool in time while in the cell coverage area. As described in the first aspect, there are several possibilities for limiting the amount of time during which a particular pool of radio resources can be used by a terminal. The configuration information for the preconfigured transmission radio resource pool may be similar or identical to that discussed above for the temporary transmission radio resource pool.

Specifically, a broadcast system information packet may, for example, directly indicate the appropriate amount of time, for example, 10 ms, 100 ms, 1000 ms for a pre-configured transmission radio resource pool. Then, depending on the particular implementation, this indicated amount of time should be interpreted by the terminal in that the pre-configured pool of transmission radio resources can be used for that specific time after, for example, receiving a broadcast system information packet. Alternatively, instead of starting the timer when the terminal receives the broadcast system information packet, the timer can start when the transmitting terminal begins to use the pre-configured pool of transmit radio resources (for example, by transmitting the scheduling assignment for direct transmission to another terminal).

Alternatively, or in addition to directly indicating the amount of time, the time during which a pre-configured pool of radio transmission resources can be used can be limited “indirectly” by setting specific conditions / events that stop the terminal from subsequently using the mentioned resources. For example, a broadcast system information packet may include an instruction associated with a preconfigured transmission radio resource pool that a terminal wishing to use these resources should also try to establish a radio connection with the base station in order to avoid the terminal being in a standby state with infinite use of such resources. At the same time, the terminal, for example, is only allowed to use the resources from the previously configured transmission radio resource pool until a connection is established and the base station assigns allocated radio resources to the terminal, which is then used instead for a possible transmission with direct communication (see period A + B + C in Fig. 18); or, if the connection cannot be established or rejected until the terminal is informed of this set-up failure (see period 0 + A in FIG. 19); or the base station at this moment, although establishing a connection with the terminal, may not allow the terminal to transmit with direct communication (see period 0 + A + B in Fig. 18). Moreover, taking into account the long time it may take for the terminal to actually use the allocated radio resource assigned by the base station to the terminal, an additional alternative can extend the time during which the pre-configured pool of radio resources can be used until the moment the terminal (after establishing radio connections with the base station and receiving from the base station dedicated radio resources for transmission with direct communication) will actually edachu feedforward SA or data by using these allocated radio resources assigned to the terminal by the base station (see. the period 0 + A + B + C + D in FIG. 18).

The actual instructions for establishing a connection may, for example, indicate a specific amount of time within which the terminal needs to (at least) begin to establish a connection (starting, for example, immediately after receiving a broadcast system information packet or after starting to use a pre-configured transmission resource pool). Another option is that the terminal is even required to initiate a connection before it is allowed to use radio resources from a pre-configured transmission radio resource pool for direct communication. For this purpose, for example, this can be understood when the terminal begins to establish a connection with the base station by transmitting the preamble of the random access procedure.

A pre-configured transmission radio resource pool can determine the actual physical radio resources (i.e., time and frequency) and can optionally also determine the specific transmission format or power associated with the physical radio resources. In addition, when the terminal is in the coverage area and uses a pre-configured pool of transmission radio resources for direct transmission, the power for these transmissions can be controlled by the base station (in the usual way).

Several different implementations of the second aspect have been described above. Below, the principles underlying the second aspect and their implementation are applied as an example to an LTE system (such as the system described in the prior art section).

In accordance with some implementations described above for the second aspect, the broadcast system information packet from the base station is adapted to allow / prevent the use of a pre-configured pool of radio transmission resources while in the coverage area and / or configure its use.

As mentioned for the first aspect, the current 3GPP standardization assumes that the use of SIB18 contains some information related to direct communication and ProSe detection, and may contain the flag or configuration information mentioned above. Of course, it should be noted that for the purposes of this second aspect, any other type of system information block can be used to transmit this information. The following is a very specific example where configuration and configuration variables are given specific names (i.e., usePreconfigResInCoverage, allowedTime, timeToInitiateRRCConnEst), and the variables are set specifically (i.e., ms100, ms200, ms300, etc., ms01 , ms05, etc.). Once again, it should be noted that for the purposes of this second aspect, any other field name may be chosen, and, in addition, the actual values of the variables may be different.

SystemInformationBlockType18 Information Element

Field descriptions SystemInformationBlockType18 commIdleTxPool
Indicates the resources by which the UE is allowed to perform direct-link transmissions while in RRC_IDLE. discInterFreqList
Indicates adjacent frequencies at which direct detection notification is supported. discIdleTxPool
Indicates the resources by which the UE is allowed to send direct discovery notifications when located in RRC_IDLE. usePreconfigResInCoverage
If included, indicates that the UE is allowed to use pre-configured resources in the cell coverage area.
allowedTime
UE can use usePreconfigResInCoverage until allowedTime . A value of ms100 means 100 ms, ms200 means 200 ms, etc.
timeToInitiateRRCConnEst
The time during which the UE must begin the RRC connection establishment procedure, i.e., initiate access to the PRACH. ms01 means 1 ms, ms05 means 5 ms, etc. A value of 'alreadyInitiated' indicates that the UE may only use pre-configured resources after initiating an RRC connection setup procedure, for example, after initiating access to the PRACH.

Important changes to this illustrative information element of type 18 of the system information block for the second aspect with respect to the prior art are made in bold and underlined for ease of identification.

As can be seen from the above, the configuration information field ʺusePreconfigResInCoverageʺ is optional, therefore, when this field is present in the broadcast system information packet, the UE can determine that the pre-configured transmission radio resource pool (mode 2 resources) is available when it is in the coverage area; in the absence of this field, the UE determines that the corresponding pre-configured transmission radio resource pool in the cell is unavailable.

The configuration variables ʺallowedTimeʺ and ʺtimeToInitiateRRCConnEstʺ as such are already known from the first aspect discussed above, and are defined for this second aspect in the same way. As is clear from the example above, they can even be determined at the same time, if so decided by the eNB, thereby allowing directly and / or indirectly limit the amount of time during which a pre-configured pool of radio transmission resources in the coverage area can be used. So, in this particular example, part of the configuration information is implemented as the ʺallowedTimeʺ variable with illustrative time values of 100 ms, 200 ms, etc., as shown above, thereby directly limiting the amount of time. By reading the value indicated by the ʺallowedTimeʺ variable, the terminal can determine how long the pre-configured pool of transmit radio resources can be used after receiving a broadcast system information packet (or after the terminal starts using resources from the temporary transmit radio resource pool for direct communication); the corresponding timer can be set, started and monitored by the UE.

Similarly, the ʺtimeToInitiateRRCConnEstʺ configuration variable can be included to indirectly limit the use of a temporary transmit radio resource pool (i.e., commTxPoolTemp) based on various exit conditions, as explained below. By using this configuration variable timeToInitiateRRCConnEst UE, an instruction is issued to try to establish an RRC connection with an eNB for an illustrative time of 1 or 5 ms, etc., as shown above. Depending on the different behavior of the UE, the UE may, for example, be allowed to use the resources of a pre-configured transmission radio resource pool until an RRC connection is established and the eNB assigns allocated radio resources to the terminal; or until the UE realizes that the RRC connection establishment has failed; or until the UE is informed by the eNB that it is not allowed to carry out direct communication in the cell; or until the direct SA or data is actually implemented using the allocated resources assigned to the UE by the eNB.

In addition, it should be noted that although this second embodiment has been explained as a separate solution that is different from the first embodiment, nevertheless, in general, this second embodiment can be combined with the first embodiment.

Third Embodiment

In relation to the D2D connection and current development, the inventors have identified additional problems. More specifically, in addition to the above problem (s) with respect to the various periods in which the implementation of the D2D UEs in various scenarios is prevented, another problem relates to the OOC UEs of state 3 and state 4. In particular, it is not yet clear how a particular UE will know whether it is in state 3 (relay of the UE CP) or in state 4. This leads to an additional problem in that the UE does not understand what resources and transmit power it should use for D2D communication.

FIG. 11 and the corresponding description of the section of the prior art explain 4 basic conditions in which the UE may be and which can be briefly described as follows:

State 1: In the cell coverage area (IC) - very close to the center of the cell

State 2: In the cell coverage area (IC) - at the cell boundary

State 3: Outside the cell coverage area — slightly outside the cell; these UEs may cause some interference to the WAN “in case” of transmission over conflicting resources with high transmit power

State 4: “Real” outside the cell coverage area - cannot interfere with the WAN even in the case of transmission over conflicting resources with high transmission power

It is clear that in states 3 and 4, the UE is outside the coverage area of the cell, but it is not clear how the UE can distinguish between state 3 and state 4, because it only knows that it is not in the coverage area, i.e., it is not based on which or SOT WAN.

Perhaps (possible) the following solution (s).

If the UE receives the PD2DSCH, it considers itself to be in State 3; in other cases, if the UE has not received PD2DSCH for some predetermined (or configurable) time, it considers itself to be in State 4. As explained in the prior art section, PD2DSCH is physical layer information sent by the eNB in the OOS (Out of Zone Coverage) UEs through some UE ICs (UE ICs forward PD2DSCH). PD2DSCH signals some resources for D2D communication. If they are received by the UE OOS, resources received in the PD2DSCH for D2D communication take precedence over any preconfigured Mode 2 resources available to the UE OOS. This is an advantage, since in other cases the use of pre-configured Mode 2 resources may cause some interference to the WAN, because in other cases these UEs will consider themselves in state 4 and can transmit over conflicting resources with high transmit power.

The UE in state 3 will again consider itself the UE in state 4 when it stops receiving PD2DSCH or D2DSS (D2D synchronization signal) for a predetermined period of time.

By specifying how the UE distinguishes between state 3 and state 4, the resources and transmit power that it should use for D2D communications can be selected / calculated in an efficient manner so as not to cause any problems (interference) when using WAN communications.

It should be noted that the third embodiment explained above can be combined with the first and / or second embodiment explained above.

Fourth Embodiment

Another problem identified in the D2D association is that it is not clear from the current standardization which UE should forward the PD2DSCH to different OOCs of the UE.

The following alternative solutions are possible. Combinations of these are also possible.

Typically, UEs that are sufficiently within the cell coverage area (for example, acceptable measured RSRP and RSRQ values of the serving cell) but are not near the center of the cell may be a good option for PD2DSCH forwarding. In particular, UEs that are located between a certain predefined threshold for radio reception (for example, for which RSRP / RSRQ measurements are between a specific threshold ʺxʺ and threshold ʺyʺ); RSRP (received power of the reference signal); RSRQ (received quality of the reference signal). In this case, threshold x and threshold y are broadcast together with the PD2DSCH content.

Another possible option for PD2DSCH forwarding are UEs that transmit / forward D2DSS. PD2DSCH content is broadcast.

Another possible solution is that the network explicitly requests specific UEs in dedicated signaling for PD2DSCH forwarding. PD2DSCH content is broadcast or signaled to the UE using dedicated signaling.

One possible combination of the above solutions is a UE that already forwards D2DSS but also has acceptable cell coverage, i.e. when RSRP or RSRQ is between the respective thresholds.

It should be noted that the fourth embodiment can be used either with one of the first, second and third embodiments, or with any combination thereof.

Fifth Embodiment

Another problem identified in the D2D communication relates to the transmit / receive operation for the D2D communication. As mentioned in the prior art section, depending on a resource allocation mode, a transmission operation in a D2D communication looks a little different. For D2D mode 1 communication, the eNB issues a D2D grant, i.e., (E-PDCCH), encrypted using D2D-RNTI, to the transmitting D2D UE, which allocates resources for SA transmission and also for data (ProSe / D2D data). More specifically, the D2D grant contains at least an SA resource index (SA resource index) indicating the time / frequency resources to be used by the transmitting D2D UEs to transmit the SA within the SA resource pool, as well as a T-RPT index and a field RB data distributions, which mainly indicate time / frequency resources for D2D data transmissions. The T-RPT index field refers to one record in a table that lists all the available T-RPT patterns, for example, the table contains 128 records. A temporary transmission resource template (T-RPT template) defines a temporary transmission resource template for D2D data transfers within a D2D resource pool.

Upon receiving D2D permission from the eNB, the transmitting D2D UE uses the SA resource index to determine the subframes and frequency resources within the SA resource pool to be used to transmit, respectively, the retransmission of the SA message. Further, the transmitting D2D UE uses at least the T-RPT index information received as part of the D2D resolution to determine subframes (and potentially also frequency resources based on some other information transmitted in the D2D resolution) to be used for transmission PDU data D2D. The function of how to obtain subframes for transmitting different D2D data PDUs is different for transmitting D2D mode 1 and mode 2. For transmitting D2D mode 2, the transmitting D2D UE will apply the T-RPT pattern to the subframes that are designated as subframes in the resource pool bitmap. Essentially, the transmitting D2D UE applies the T-RPT pattern to those subframes that are defined as potential D2D subframes for transmitting mode 2 in accordance with the D2D mode 2 data transmission resource pool. Examples are shown in FIG. 22.

1s in the bitmap of a transmission resource pool means the so-called D2D subframes, i.e., subframes reserved for transmitting D2D mode 2. The T-RPT template applies to these D2D subframes. As seen in FIG. 22, these D2D subframes in which the corresponding T-RPT record is 1 should be used for transmitting D2D data PDUs (subframes in which both the resource pool bitmap record and the T-RPT bitmap record are 1). As already mentioned in the prior art section, to distribute Mode 2 resources, the transmitting UE D2D autonomously selects a T-RPT pattern and signals it to the SA in such a way that the receiving D2D UEs are able to determine (after correctly decoding the SA) based on the received T-RPT pattern frequency resource of data transmissions D2D. There is no D2D permission to transmit D2D mode 2.

To transmit Mode 2 D2Ds, the eNB distributes the T-RPT template to be used for D2D transmission and signals it to the transmitting D2D UE by enabling D2D, as already explained above.

Given the lack of a D2D transmission resource pool for mode 1, the parameters in the T-RPT should be directly applied to the physical uplink subframes, since the uplink subframes may be D2D subframes. In accordance with one illustrative embodiment, the transmitting D2D UE must apply the T-RPT pattern indicated in the T-RPT pattern index in D2D resolution to all subframes in the resource pool bitmap, i.e., subframes in which the bitmap entry represents 1 as well as 0. An example of D2D mode 1 data transmission is depicted in FIG. 21.

As you can see, the same T-RPT template that was used in the sample scenario illustrating the transfer of D2D mode 2 is also taken here; however, for mode 1, it applies to all subframes (UL) in the resource pool. Since there is no data transfer resource pool defined / configured for mode 1, the transmitting D2D UE can apply the T-RPT pattern to either the mode 2 data transfer pool or, alternatively, to the data receive resource pool. The main difficulty is that some reference signal is needed corresponding to the initial subframe in which the T-RPT pattern is applied for mode 1. Alternatively, there may be some time relationship between the first D2D data transmission and the predefined SA. For example, the first opportunity to transmit D1D mode 1 data, i.e., this is the initial sub-frame of the T-RPT template, occurs x ms after the last transmission of the SA message.

The T-RPT pattern is used in different ways depending on whether the transmitting UE D2D uses D2D mode 1 or mode 2 data transmission. Therefore, the receiving D2D UE must be able to distinguish between D2D mode 1 or mode 2 transmissions. More specifically, when receiving SA in the pool of the SA resources, the receiving D2D UE must know whether the SA was transmitted using the D2D transmission of mode 1 or mode 2 in order to be able to accurately interpret the T-RPT pattern, i.e., to determine the exact time / frequency resources of the respective D2D data transmissions. According to another illustrative embodiment, the SA message contains an explicit indicator of the used resource allocation mode for D2D communication, i.e., a new field in the SA message indicates whether mode 1 or mode 2 was used to transmit D2D data.

Alternatively, the transmission / allocation of resources is indicated implicitly by the T-RPT pattern signaled within the SA message. Available T-RPT templates that are either preconfigured or listed in the table are divided into two sets, one set of T-RPT templates is used for mode 1 transfers, and a second set of T-RPT templates is used for mode 2. For example, based on 128 different T-RPT patterns, patterns 0-63 can be used for D2D mode 1 transmissions, while T-RPT patterns with an index of 64-127 are reserved for mode 2. Based on the received T-RPT index in SA, the receiving UE D2D can understand whether the transmitting UE uses mode 1 or mode 2 resource allocation.

As an additional alternative solution in accordance with another illustrative embodiment, the transfer / allocation of resources can be obtained by the value of the TA field contained in the SA. Since mode 1 transmissions and mode 2 transmissions use different temporary transmission modes, the receiving UE can distinguish between mode 1 and mode 2 transmissions based on the value of this field. For example, the TA value for transmitting mode 2 is always zero, while for mode 1, the TA value is set to the NTA value of the UE, i.e., the UE uses the standard uplink transmission mode for D2D transmissions of mode 1.

As an additional alternative, the resource / transmission allocation mode may be indicated implicitly by the frequency resources used to transmit the SA message. For example, SA messages sent by transmitting Mode 2 UEs are different from the frequency resources used for SA transmissions of Mode 1 UEs. More specifically, a transmission resource pool for Mode 2 is different from resources assigned by an eNB for SA transmissions (Mode 1).

Another alternative solution in accordance with a further illustrative embodiment of the invention is to determine the length of the bitmap of the T-RPT template so that there is no uncertainty between the transmissions of mode 1 and mode 2. More specifically, the length of the bitmap of the T-RPT template should be same as the length of the resource pool bitmap to which the T-RPT pattern applies. If we take the examples depicted in FIG. 21 and 22, the length of the T-RPT template should be 30 bits.

Since the T-RPT pattern for both mode 1 and mode 2 applies to the same initial subframe, for example, the initial subframe of the resource pool, the receiving UE D2D does not have to distinguish between transmission of mode 2 and mode 1.

It should be noted that the fifth embodiment can be used together with either one of the first, second, third and fourth embodiments, or with any combination thereof.

Hardware and software implementation of the present invention

Other illustrative embodiments relate to the implementation of the above various embodiments using hardware and software. In this regard, user equipment (mobile terminal) and eNodeB (base station) are offered. The user equipment and the base station are configured to implement the methods described herein.

It is also understood that various embodiments may be implemented or performed using computing devices (processors). A computing device or processor may, for example, be universal processors, digital signal processors (DSPs), specialized integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, etc. Various embodiments may also be implemented or implemented using a combination of these devices.

In addition, various embodiments may also be implemented using software modules that are executed by a processor or directly in hardware. In addition, there is the possibility of a combination of software modules and hardware implementation. Software modules can be stored on any type of computer-readable media, for example, RAM, EPROM, EEPROM, flash memory, registers, hard drives, CD-ROM, DVD, etc.

It should also be noted that individual features of various embodiments may, individually or in arbitrary combination, be the subject of another embodiment.

One skilled in the art will appreciate that various variations and / or modifications are possible in the present invention, as shown in particular embodiments. The present embodiments are therefore to be regarded in all respects as illustrative and not restrictive.

Claims (30)

1. A method of distributing radio resources to a transmitting terminal for direct communication to transmit over a straight line connection to a receiving terminal in a communication system, the method comprising the following steps performed by the transmitting terminal, in which: receive from the base station a broadcast broadcast of system information; if the broadcast system information includes information about the transmission radio resource pool intended for the idle state, which information indicates the radio resources that can be used by the transmitting terminals in the idle state, transmitting directly to the receiving terminal via the forward link connection using a transmission radio resource pool for a wait state; and if the broadcast system information broadcast does not include information about the transmission radio resource pool intended for the standby state, and includes information about the temporary transmission radio resource pool, which information about the temporary transmission radio resource pool indicates radio resources that can be used by transmitting terminals in the state standby or connected state, perform direct transmission to the receiving terminal over the forward link connection using bp seminal pool of radio transmission resources. 2. The method according to claim 1, wherein the temporary pool of transmission radio resources can be used by the transmitting terminal only until one of the following occurs: allocated radio resources that can be used for direct transmission, are assigned to the transmitting terminal by the base station, the transmitting terminal transmits for direct communication for the first time using the allocated radio resources assigned by the base station to the transmitting terminal, the procedure for establishing a radio connection initiated by the transmitting terminal fails, the transmitting terminal is informed by the base station that the transmitting terminal is not allowed to perform direct communication in the cell of the base station; while the allocated radio resources are radio resources selected from the assigned pool of transmission radio resources assigned to the transmitting terminal by the base station, or the allocated radio resources are radio resources assigned to the transmitting terminal by the base station in response to a resource request from the transmitting terminal for transmission carried out in direct communication. 3. The method of claim 1, wherein the temporary transmission radio resource pool indicates a first set of radio resources that can be used to directly communicate a scheduling assignment to a receiving terminal over a forward link connection, the scheduling assignment indicating the radio resources to be used by the transmitting terminal for direct communication, subsequent data transfer to the receiving terminal by connecting a direct communication line, or in which a temporary pool of radio resources Vaeth second set of radio resources that can be used for the implementation of direct communication, the data to a receiving terminal over a forward link connection. 4. The method of claim 1, wherein the broadcast system information is a type 18 system information unit (SIB). 5. The method of claim 1, wherein the transmitting terminal uses a temporary transmit radio resource pool when a timer expires (T300) to establish a radio resource control (RRC) connection. 6. The method of claim 1, wherein broadcasting the system information indicates whether a temporary transmission radio resource pool can be used when the transmitting terminal is within the coverage area of the base station cell. 7. The method of claim 2, wherein the allocated radio resources begin with a subframe after the subframe in which the transmitting terminal transmits a scheduling assignment (SA) message. 8. A transmitting terminal for performing, through direct communication, transmission over a straight line connection to a receiving terminal in a communication system, the transmitting terminal comprising: a receiver, which during its operation receives from the base station a broadcast broadcast of system information; a circuit that is connected to the receiver and which during its operation, if the broadcast system information includes information about the transmission radio resource pool intended for the idle state, which information indicates the radio resources that can be used by the idle transmitting terminals, performs direct transmission to the receiving terminal via the forward link connection using a transmission radio resource pool for a wait state; and if the broadcast system information broadcast does not include information about the transmission radio resource pool intended for the standby state, and includes information about the temporary transmission radio resource pool, which information about the temporary transmission radio resource pool indicates radio resources that can be used by transmitting terminals in the state standby or connected state, performs direct transmission to the receiving terminal over the forward link connection using bp seminal pool of radio transmission resources. 9. The transmitting terminal according to claim 8, wherein the temporary pool of transmission radio resources can be used by the transmitting terminal only until one of the following occurs: allocated radio resources that can be used for direct transmission, are assigned to the transmitting terminal by the base station, the transmitting terminal transmits for direct communication for the first time using the allocated radio resources assigned by the base station to the transmitting terminal, the procedure for establishing a radio connection initiated by the transmitting terminal fails, the transmitting terminal is informed by the base station that the transmitting terminal is not allowed to perform direct communication in the cell of the base station; while the allocated radio resources are radio resources selected from the assigned pool of transmission radio resources assigned to the transmitting terminal by the base station, or the allocated radio resources are radio resources assigned to the transmitting terminal by the base station in response to a resource request from the transmitting terminal for transmission carried out in direct communication. 10. The transmitting terminal of claim 8, wherein the broadcast system information is a type 18 system information unit (SIB). 11. The transmitting terminal according to claim 8, which during its operation uses a temporary pool of transmission radio resources when the timer expires (T300) to establish a radio resource control (RRC) connection. 12. The transmitting terminal of claim 8, wherein the broadcast system information indicates whether a temporary pool of transmission radio resources can be used when the transmitting terminal is within the coverage area of the cell of the base station. 13. The transmitting terminal of claim 9, wherein the allocated radio resources begin with a subframe after the subframe in which the transmitting terminal transmits a scheduling assignment (SA) message.

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