BR112016020289B1 - COMMUNICATION EQUIPMENT FOR DEVICE TO DEVICE (D2D) COMMUNICATION, COMMUNICATION METHOD FOR DEVICE TO DEVICE COMMUNICATION, COMMUNICATION EQUIPMENT, COMMUNICATION METHOD, AND INTEGRATED CIRCUIT - Google Patents

Abstract

COMMUNICATION EQUIPMENT FOR DEVICE TO DEVICE (D2D) COMMUNICATION, COMMUNICATION METHOD FOR DEVICE TO DEVICE COMMUNICATION, COMMUNICATION EQUIPMENT, COMMUNICATION METHOD, AND INTEGRATED CIRCUIT The present invention relates to a D2D capable of a communication method and a transmitting user equipment, which transmits data to a receiving user equipment via a direct link data channel, uses the services of the eNodeB in order to have resources allocated to transmit said data. For this purpose, the UE sends to the eNB scheduling information using resources in a dedicated subframe for standard uplink communication through the eNodeB, instead of using resources in the dedicated subframe for D2D data transmission. In order to allow the eNB to distinguish whether the received scheduling request is for allocation of resources for data transmission over the direct link channel or over the eNB, the UE may also send, along with the scheduling information, associated identification information. to programming information

Description

FIELD OF INVENTION

[001] The invention relates to a system and method for performing a programming request procedure in a device-to-device communication system. The invention is also providing user equipment to carry out the methods described herein.

TECHNICAL HISTORY LONG TERM EVOLUTION (LTE)

[002] Third generation (3G) mobile systems based on WCDMA radio access technology are being employed on a wide scale around the world. A first step in the improvement or evolution of this technology entails introducing High-Speed Downlink Packet Access (HSDPA) and a reinforced uplink, also referred to as High Speed Uplink Packet Access (HSUPA), giving a radio access technology that is highly competitive.

[003] In order to be prepared to further increase user demands and to be competitive against new radio access technologies, 3GPP has introduced a new mobile communication system which is called Long Term Evolution (LTE). LTE is designed to meet carrier needs for high-speed data and media transport as well as high-capacity voice support for the next decade. The ability to deliver high bitrates is a key measure for LTE.

[004] The specification of the work item (Wl) in the Long Term Evolution (LTE) called Evolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN) is finalized as Release 8 (LTE Rel. 8). The LTE system represents efficient packet-based radio access and radio access networks that provide complete IP-based functionalities with low latency and low cost. Detailed system requirements are given in 3GPP, TR 25.913 (“Requirements for Evolved UTRA and Evolved UTRAN”, www.3gpp.org). In LTE, scalable multicast bandwidths are specified such as 1.4, 3.0, 5.0, 10.0, 15.0 and 20.0 MHz in order to achieve flexible system deployment using a certain spectrum. In the downlink, radio access based on Orthogonal Frequency Division Multiplexing (OFDM) was adopted because of its inherent immunity to multipath interference (MPI) due to a low symbol rate, the use of a cyclic prefix ( CP), and its affinity to different transmission bandwidth arrangements. Radio access based on single carrier frequency division multiple access (SC-FDMA) was adopted in the uplink as providing wide area coverage was prioritized over improving peak data rate considering the strength user equipment (UE) restricted transmission. Many core packet radio access techniques are employed including multiple-input multiple-output (MIMO) channel transmission techniques, and a highly effective control signaling structure is achieved in Rel. 8 LTE.

E-UTRAN ARCHITECTURE

[005] The total architecture is shown in figure 1 and a more detailed representation of the E-UTRAN architecture is given in figure 2. The E-UTRAN consists of one or more eNodeBs, providing the E-UTRA user plane (PDCP/ RLC/MAC/PHY) and control plane protocol (RRC) terminations towards the UE. The eNodeB (eNB) hosts the Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Control Protocol (PDCP) layers that include data header compression functionality. user plan and encryption. It also provides Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions including radio resource management, admission control, scheduling, executing negotiated uplink Quality of Service (UL QoS), transmitting cell information, encrypting/decrypting user data and control plane, and compressing/ decompression of downlink/uplink user plane packet headers. The eNodeBs are interconnected to each other via the X2 interface.

[006] The eNodeBs are also connected through the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) through the S1-MME and to the Service Gateway (S-GW) via S1-U. The S1 interface supports a many-to-many relationship between MMEs/Service Gateways and eNodeBs. The SGW determines and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies (terminating the S4 interface and retransmitting traffic between 2G/3G and PDN GW systems). For UEs in idle state, the S-GW terminates the downlink data path and triggers paging when the downlink data arrives at the user equipment. It manages and stores user equipment contexts, for example, IP support service parameters, internal network routing information. It also performs replication of user traffic in case of lawful interception.

[007] The MME is the main control node for the LTE access network. It is responsible for the user tracking and paging procedure in idle mode including retransmissions. It is involved in the carrier activation/deactivation process and is also responsible for choosing the S-GW for a user equipment at initial attachment and at the time of intra-LTE handover involving Core Network (CN) node relocation. It is responsible for user authentication (through interaction with HSS). The No Access Stratum (NAS) signaling terminates at the MME and is also responsible for generating and allocating temporary identities to user equipment. It verifies the UE's authorization to camp on the service provider's Public Land Mobile Network (PLMN) and applies roaming restrictions of the user's equipment. The MME is the termination point in the network for encryption/integrity protection for NAS signaling and handles core security management. Legal signal interception is also supported by MME. The MME also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating in the MME of the SGSN. The MME also terminates the S6a interface towards the home's HSS for roaming user equipment.

COMPONENT CARRIER STRUCTURE IN LTE

[008] The downlink component carrier of an LTE 3GPP system is subdivided in the time-frequency domain into so-called subframes. In LTE 3GPP, each subframe is divided into two downlink slots as shown in Figure 3, where the first downlink slot comprises the control channel region (PDCCH region) within the first OFDM symbols. Each subframe consists of a given number of time-domain OFDM symbols (12 or 14 OFDM symbols in LTE 3GPP (Release 8)), where each OFDM symbol spans the entire carrier bandwidth of the component. OFDM symbols each thus consist of several modulation symbols transmitted on respective subcarriers.

[009] also shown in Figure 4.

[010] Assuming a multicarrier communication system, for example, that employs OFDM, as, for example, used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be assigned by the programmer is a “resource block”. ”. A physical resource block is defined jvfmb as consecutive OFDM symbols of in the time domain and consecutive subcarriers of in the frequency domain as exemplified in Figure 4. In LTE 3GPP (Release 8), a physical resource block thus consists of resource elements

[011] corresponding to a slot in the time domain and 180 kHz in the frequency domain (for additional details on the downlink resource grid, see, for example, 3GPP TS 36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, version 8.9.0 or 9.0.0, section 6.2, available at http://www.3gpp.org and incorporated herein by reference).

[012] The term “component carrier” refers to a combination of several resource blocks. In future LTE releases, the term “component carrier” will no longer be used; instead, the terminology is changed to “cell,” which refers to a combination of downlink and, optionally, uplink resources. The link between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information transmitted on the downlink resources.

MORE ADVANCES FOR LTE (LTE-A)

[013] The frequency spectrum for IMT-Advanced was decided at the World Radiocommunication Conference 2007 (WRC-07). Although the total frequency spectrum for IMT-Advanced has been decided, the actual available frequency bandwidth is different according to each region or country. After the draft available frequency spectrum was decided, however, standardization of a radio interface began in the 3rd Generation Partnership Program (3GPP). At the 3GPP TSG RAN meeting #39, the Study Item description in “Further Advancements for E-UTRA (LTE-Advanced)” was approved in 3GPP. The study item covers the technological components to be considered for the evolution of E-UTRA, for example, to meet the requirements in IMT-Advanced. Two key technology components that are currently under consideration for LTE-A are described below.

[014] Carrier Aggregation in LTE-A to support wider bandwidth

[015] The bandwidth that the LTE-Advanced system is capable of supporting is 100 MHz, while the LTE system can only support 20 MHz. Nowadays, the lack of radio spectrum has become a hindrance to the development of networks wireless, and as a result it is difficult to find a spectrum band that is wide enough for the LTE-Advanced system. Consequently, it is urgent to find a way to gain a wider radio spectrum band, where one possible answer is carrier aggregation functionality.

[016] In carrier aggregation, two or more component carriers (CCs) are aggregated in order to support wider transmission bandwidths up to 100 MHz. Multiple cells in the LTE system are aggregated into a wider channel in the LTE system. Advanced that is wide enough to 100 MHz, although these cells in LTE are in different frequency bands. A UE can receive or transmit simultaneously on one or multiple CCs depending on its capabilities: - a Rel-10 UE with reception and/or transmission capabilities for AC can receive and/or transmit simultaneously on multiple CCs corresponding to multiple service cells; - a Rel-8/9 UE can receive on a single CC and transmit on a single CC corresponding to a service cell only.

[017] Carrier Aggregation (CA) is supported for both contiguous and non-contiguous CCs with each CC limited to a maximum of 110 Resource Blocks in the frequency domain using Rel-8/9 numerology.

[018] It is possible to configure a UE to aggregate a different number of CCs originating from the same eNB and possibly different bandwidths in the UL and DL.

[019] It is possible to configure a 3GPP LTE-A (Release 10) compliant user equipment to aggregate a different number of component carriers originating from the same eNodeB (base station) and possibly different bandwidths in the uplink and downlink . The number of downlink component carriers that can be configured depends on the downlink aggregation capability of the UE. Conversely, the number of uplink component carriers 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 component carriers than downlink component carriers.

[020] In a typical TDD deployment, the number of component carriers and the bandwidth of each component carrier in the uplink and downlink are the same. Component carriers that originate from the same eNodeB do not need to provide the same coverage.

[021] Component carriers must be compatible with LTE Rel-8/9. Nevertheless, existing mechanisms (e.g. bus) can be used to prevent Rel-8/9 UEs to camp on a component carrier.

[022] The spacing between the center frequencies of contiguously aggregated component carriers must be a multiple of 300 kHz. This is in order to be compatible with the 100 kHz frequency tracking of 3GPP LTE (Release 8/9) and at the same time preserve the orthogonality of the 15 kHz-spaced subcarriers. Depending on the aggregation scenario, n x 300 kHz spacing may be facilitated by inserting a low number of unused subcarriers between contiguous component carriers.

[023] The nature of multiple carrier aggregation is only exposed up to the MAC layer. For both uplink and downlink, there is a HARQ entity required in the MAC for each aggregated component carrier. There is (in the absence of SUMIMO for uplink) at most one transport block per component carrier. A transport block and its potential HARQ retransmissions need to be mapped onto the same component carrier.

[024] The Layer 2 structure with carrier aggregation enabled is shown in Figure 5 and Figure 6 for the downlink and uplink, respectively. Transport channels are described between MAC and Layer 1, logical channels are described between MAC and RLC.

[025] When carrier aggregation (CA) is configured, the UE only has an RRC connection to the network. On RRC connection establishment/reestablishment/handover, a service cell provides the NAS mobility information (e.g., TAI), and on RRC connection reestablishment/handover, a service cell provides the security input. This cell is referred to as the Primary Cell (PCell). In the downlink, the carrier corresponds to the PCell in Downlink Primary Component Carrier (DL PCC) while in the uplink it is the Uplink Primary Component Carrier (UL PCC).

[026] Depending on the capabilities of the UE, Secondary Cells (SCells) can be configured to form a set of service cells with the PCell. In the downlink, the carrier that corresponds to a SCell is a Downlink Secondary Component Carrier (DL SCC), while in the uplink it is an Uplink Secondary Component Carrier (UL SCC).

[027] The configured set of service cells for a UE therefore always consists of a PCell and one or more SCells: - For each SCell, the UE's use of uplink resources, in addition to those of the downlink, is configurable (the number of configured DL SCCs is therefore always greater than or equal to the number of UL SCCs and no SCell can be configured for uplink use (resources only)); - From a UE point of view, each uplink resource belongs to only one serving cell; - The number of service cells that can be configured depends on the aggregation capacity of the UE; - PCell can only be changed with the delivery procedure (that is, with the main security change and RACH procedure); - PCell is used for PUCCH transmission; - Unlike SCells, PCell cannot be deactivated; - Reestablishment is triggered when PCell experiences Rayleigh fading (RLF), not when SCells experience RLF; - Non-access stratum (NAS) information is taken from the downlink PCell;

[028] Configuration and reconfiguration of component carriers can be performed by RRC. Activation and deactivation are done through MAC control elements. In intra-LTE delivery, RRC can also add, remove, or reconfigure SCells for use in the target cell. Reconfiguration, addition and removal of SCells can be performed by RRC. In intra-LTE delivery, RRC can also add, remove, or reconfigure SCells for use with the target PCell. When adding a new SCell, dedicated RRC signaling is used to send all required system information from the SCell, i.e., while in connected mode, the UEs do not need to acquire transmitted system information directly from the SCells.

[029] When a user equipment is configured with carrier aggregation, there is a pair of uplink and downlink component carriers that are always active. The downlink component carrier of that pair may also be referred to as the “DL anchor carrier”. The same also applies to the uplink.

[030] When carrier aggregation is configured, a user equipment can be programmed over multiple component carriers simultaneously, but at most one random access procedure must be continuous at any time. Transverse carrier scheduling allows the PDCCH of one component carrier to schedule resources on another component carrier. For this purpose, a component carrier identification field is introduced into the respective DCI formats, called CIF.

[031] A connection between uplink and downlink component carriers allows identification of the uplink component carrier to which the concession applies when there is no transversal carrier programming. The connection of downlink component carriers to uplink component carriers does not necessarily need to be one by one. In other words, more than one downlink component carrier can connect to the same uplink component carrier. At the same time, a downlink component carrier can only connect to an uplink component carrier.

LTE RRC STATES

[032] Below, mainly the two main states in LTE are described: “RRC_IDLE” and “RRC_CONNECTED”.

[033] In RRC_IDLE, the radio is not active, but an ID is assigned and tracked by the network. More specifically, a mobile terminal in RRC_IDLE performs cell selection and reselection - in other words, it decides which cell to camp in. The cell (re)selection process takes into account the priority of each applicable frequency of each applicable Radio Access Technology (RAT), radio link quality, and cell status (i.e., whether a cell is barred or reserved). An RRCJDLE mobile terminal monitors a paging channel to determine incoming calls, and also acquires system information. The system information mainly consists of the parameters by which the network (E-UTRAN) can control the cell (re)selection process. RRC specifies the applicable control signaling for a mobile terminal in RRC_IDLE, called paging and system information. The mobile terminal behavior in RRC_IDLE is specified in TS 25.912, e.g., Chapter 8.4.2 incorporated herein by reference.

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

LOGICAL AND TRANSPORT CHANNELS

[035] The MAC layer provides a data transfer service to the RLC layer through logical channels. Logical channels are either Logical Control Channels that carry control data, such as RRC signaling, or Logical Traffic Channels that carry user plane data. The Transmission Control Channel (BCCH), the Paging Control Channel (PCCH), the Common Control Channel (CCCH), the Multicast Control Channel (MCCH), and the Dedicated Control Channel (DCCH) are Logical Control. Dedicated Traffic Channel (DTCH) and Multicast Traffic Channel (MTCH) are Logical Traffic Channels.

[036] Data from the MAC layer is exchanged with the physical layer through Transport Channels. Data is multiplexed into transport channels that depend on how it is transmitted over the air. Transport channels are classified as downlink or uplink as follows. The Broadcast Channel (BCH), Downlink Shared Channel (DL-SCH), Paging Channel (PCH) and Multicast Channel (MCH) are downlink transport channels, while the Uplink Shared Channel (UL-SCH) and the Random Access Channel (RACH) are uplink transport channels.

[037] A multiplexing is then performed between the logical channels and transport channels in the downlink and uplink, respectively.

LAYER 1/LAYER 2 CONTROL SIGNALING (L1/L2)

[038] In order to inform programmed users of their allocation state, the transport format, and other data-related information (e.g., HARQ information, transmit power control (TPC) commands), L1 control signaling /L2 is transmitted on the downlink with the data. The L1/L2 control signaling is multiplexed with the downlink data in a subframe, assuming that user allocation can change from subframe to subframe. It should be noted that user allocation can also be performed on a TTI (Transmission Time Interval) basis, where the TTI length is a multiple of the subframes. The length of the TTI can be fixed in a service area for all users, it can be different for different users, or it can be dynamic for each user. Generally, L1/2 control signaling only needs to be transmitted once per TTI. L1/L2 control signaling is transmitted on the Physical Downlink Control Channel (PDCCH). A PDCCH carries a message as a Downlink Control Information (DCI), which includes resource assignments and other control information for a mobile terminal or groups of UEs. In general, multiple PDCCHs can be transmitted in a subframe.

[039] It should be noted that in LTE 3GPP, assignments for uplink data transmissions, also referred to as uplink scheduling grants or uplink resource assignments, are also transmitted on the PDCCH.

[040] With regard to scheduling grants, the information sent in L1/L2 control signaling can be separated into the following two categories, Shared Control Information (SCI) that carries Cat 1 information and Downlink Control Information (DCI) which carries Cat 2/3 information.

[041] Shared Control Information (SCI) that carries Cat 1 information

[042] The shared control information part of the L1/L2 control signaling contains information related to resource allocation (indication). The shared control information typically contains the following information: - A user identity indicating that the user(s) owns the allocated resources. - RB allocation information to indicate the resources (Resource Blocks (RBs)) to which user(s) is/are allocated. The number of resource blocks allocated can be dynamic. - The duration of the assignment (optional), if an assignment over multiple subframes (or TTIs) is possible.

[043] Depending on the configuration of other channels and the configuration of the Downlink Control Information (DCI) - see below - the shared control information may additionally contain information such as ACK/NACK for uplink transmission, uplink scheduling information, information in the DCI (resource, MCS, etc.).

Downlink Control Information (DCI) carrying Cat 2/3 information

[044] The downlink control information portion of the L1/L2 control signaling contains information related to the transmission format (Cat 2 Information) of data transmitted to a programmed user indicated by the Cat 1 information. In case of using ARQ (Hybrid) as a relay protocol, the Cat 2 information carries the HARQ (Cat 3) information. The downlink control information only needs to be decoded by the user programmed in accordance with Cat 1. The downlink control information typically contains information on: - Cat 2 information: Modulation scheme, transport block size (payload) or coding rate, information related to MIMO (Multiple Input and Multiple Output), etc. Either the transport block (or payload size) or the code rate can be signaled. In any case, these parameters can be calculated from each other by using the modulation scheme information and resource information (number of resource blocks allocated). - Cat 3 information: HARQ related information, e.g. hybrid ARQ process number, redundancy version, retransmission sequence number.

[045] Downlink control information occurs in several formats that differ in total size and also in the information contained in their fields. The different DCI formats that are currently defined for LTE are as follows and described in detail in 3GPP TS 36.212, “Multiplexing and channel coding”, section 5.3.3.1 (available at http://www.3gpp.org and incorporated here by reference).

[046] Format 0: DCI Format 0 is used for transmitting resource grants to PUSCH.

[047] For more information regarding the DCI formats and particular information that is transmitted in the DCI, please refer to the technical standard or LTE - A UMTS Long Term Evolution - From Theory to Practice, Edited by Stefania Sesia, Issam Toufik, Matthew Baker, Chapter 9.3, incorporated herein by reference.

Downlink & Uplink Data Transmission

[048] With respect to downlink data transmission, L1/L2 control signaling is transmitted on a separate physical channel (PDCCH), with downlink packet data transmission. This L1/L2 control signaling typically contains information: - The physical resource(s) on which data is transmitted (e.g., subcarriers or blocks of subcarriers in the case of OFDM, codes in the case of CDMA). This information allows the mobile terminal (receiver) to identify the resources on which data is transmitted. - When user equipment is configured to have a Carrier Indication Field (CIF) in L1/L2 control signaling, this information identifies the component carrier for which specific control signaling information is intended. This allows assignments to be sent on a component carrier that is destined for another component carrier (“cross-carrier scheduling”). This other, transverse programmed component carrier could be, for example, a component carrier minus PDCCH, that is, the transverse programmed component carrier does not carry any L1/L2 control signaling. - The Transport Format, which is used for transmission. This can be the size of the data transport block (payload size, size of information bits), the level of MCS (Modulation and Coding Scheme), the Spectral Efficiency, the code rate, etc. This information (typically resource allocation (e.g., the number of resource blocks assigned to the user equipment)) allows the user equipment (receiver) to identify the bit size of the information, the modulation scheme, and the rate code in order to begin the demodulation, rate matching and decoding process. The modulation scheme can be explicitly signaled. - Hybrid ARQ (HARQ) information: HARQ process number: Allows the user equipment to identify the hybrid ARQ process into which the data is mapped. Sequence Number or New Data Indicator (NDI): Allows user equipment to identify whether the transmission is a new packet or a retransmitted packet. If soft blending is implemented in the HARQ protocol, the sequence number or new data pointer with the HARQ process number allows soft blending of transmissions to a PDU before decoding. Redundancy and/or constellation version: Tells the user equipment which hybrid ARQ redundancy version is used (required for rate matching) and/or which modulation constellation version is used (required for demodulation). - UE Identity (UE ID): Tells which user equipment the L1/L2 control signaling is intended for. In typical implementations, this information is used to mask the CRC from L1/L2 control signaling to prevent other user equipment from reading this information.

[049] To enable uplink packet data transmission, L1/L2 control signaling is transmitted in the downlink (PDCCH) to tell the user equipment about the transmission details. This L1/L2 control signaling typically contains information: - The physical resource(s) on which the user equipment must transmit data (e.g., subcarriers or subcarrier block in the case of OFDM, codes in the case of CDMA). - When user equipment is configured to have a Carrier Indication Field (CIF) in L1/L2 control signaling, this information identifies the component carrier for which the specific control signaling information is intended. This allows assignments to be sent to one component carrier that are intended for another component carrier. This other, transverse programmed component carrier may be, for example, a component carrier minus PDCCH, that is, the transverse programmed component carrier that does not carry any L1/L2 control signaling. - L1/L2 control signaling for uplink grants is sent on the DL component carrier that is bonded with the uplink component carrier or on one of several DL component carriers if multiple DL component carriers bond to the same uplink component carrier. UL component. - The Transport Format, user equipment must be used for transmission. This can be the block size of the data (size of the payload, size of the information bits), the level of MCS (Modulation and Coding Scheme), the Spectral Effectiveness, the code rate, etc. This information (typically with the resource allocation (e.g., the number of resource blocks assigned to the user equipment)) allows the user equipment (transmitter) to choose the information bit size, modulation scheme, and rate of code in order to begin the modulation, rate matching, and coding process. In some cases, the modulation scheme may be signaled explicitly. - Hybrid ARQ Information: HARQ Process Number: Tells the user's equipment from which hybrid ARQ process it should get data. Sequence number or new data indicator: Tells the user equipment to transmit a new packet or to retransmit a packet. If soft blending is implemented in the HARQ protocol, the sequence number or new data pointer with the HARQ process number allows soft blending of transmissions to a data protocol unit (PDU) before decoding. Redundancy and/or constellation version: Tells user equipment which hybrid ARQ redundancy version to use (prompted for rate matching) and/or which modulation constellation version to use (prompted for modulation). • UE Identity (UE ID): Tells which user equipment should transmit data. In typical implementations, this information is used to mask the CRC from L1/L2 control signaling to prevent other user equipment from reading this information.

[050] There are several different possibilities how to transmit exactly the pieces of information mentioned above in uplink and downlink data transmission. Furthermore, in the uplink and downlink, the L1/L2 control information may also contain additional information or may omit some information. For example: • HARQ process number may not be necessary, that is, not signaled, in the case of a synchronous HARQ protocol. • A redundancy and/or constellation version may not be added and therefore not signaled, if Chase Combination is used (always the same redundancy and/or constellation version) or if the sequence of redundancy and/or constellation versions constellation is predefined. • Power control information may additionally be included in control signaling. • MIMO-related control information, such as, for example, precoding, may additionally be included in the control signaling. • In case of multiple codeword MIMO, transmission transport format and/or HARQ information for multiple codewords may be included.

[051] For uplink resource assignments (on the Physical Uplink Shared Channel (PUSCH)) signaled on PDCCH in LTE, the L1/L2 control information does not contain a HARQ process number, since the HARQ protocol Synchronous is employed for LTE uplink. The HARQ process to be used for an uplink transmission is given by timing. Furthermore, it should be noted that the redundancy version (RV) information is encoded together with the transport format information, that is, the RV information is embedded in the transport format (TF) field. The Transport Format (TF), respectively modulation and coding scheme (MCS) field, has, for example, a size of 5 bits, which corresponds to 32 entries. 3 TF/MCS table entries are reserved to indicate redundancy versions (RVs) 1, 2, or 3. The remaining MCS table entries are used to signal the MCS level (TBS) by implicitly indicating RV0. The size of the PDCCH CRC field is 16 bits.

[052] For downlink assignments (PDSCH) signaled in PDCCH in LTE, the Redundancy Version (RV) is signaled separately in a two-bit field. Furthermore, the modulation order information is encoded with the transport format information. Similar to the uplink case there is a 5-bit MCS field signaled in PDCCH. 3 of the inputs are reserved to signal an explicit modulation order, providing no Transport format information (Transport block). For the remaining 29 inputs, modulation order and Transport block size information are signaled.

UPLINK ACCESS SCHEME FOR LTE

[053] For Uplink transmission, effective power user terminal transmission is required to maximize coverage. Single-carrier transmission combined with FDMA with dynamic bandwidth allocation was chosen as the uplink transmission scheme of evolved UTRA. The main reason for the preference for single carrier transmission is the peak power to average power ratio (PAPR), compared to multicarrier signals (OFDMA), and the effectiveness of the corresponding improved power amplifier and the assumed better coverage. (higher data rates for a given terminal peak power). During each time slot, Node B assigns users a unique time/frequency resource for transmitting user data, thus ensuring intracellular orthogonality. An orthogonal access in the uplink promises increased spectral efficiency by eliminating intracellular interference. Interference due to multipath propagation is handled at the base station (Node B), aided by the insertion of a cyclic prefix into the transmitted signal.

[054] The basic physical resource used for data transmission consists of a frequency resource of size BWgrant during a time interval, for example a 0.5 ms subframe, into which the encoded bits of information are mapped. It should be noted that a subframe, also referred to as a transmission time slot (TTI), is the smallest time slot for transmitting user data. Therefore, it is possible to assign a BWgrant frequency resource over a longer period of time than a TTI to a user by concatenating subframes.

UPLINK PROGRAMMING SCHEME FOR LTE

[055] The uplink scheme allows both scheduled access, that is, controlled by eNB, and contention-based access.

[056] In the case of scheduled access, the UE is allocated a certain frequency resource for a certain time (i.e., a time/frequency resource) for uplink data transmission. However, some time/frequency resources may be allocated for access to the containment base; Within these time/frequency resources, UEs can transmit without being programmed first. A scenario where UE is making an access to the contention base is, for example, random access, that is, when UE is making initial access to a cell or to require uplink resources.

[057] For scheduled access, the Node B scheduler assigns the user a unique frequency/time resource for uplink data transmission. More specifically, the programmer determines - which UE(s) is/are allowed to transmit, - which physical channel resources (frequency), - Transport format (Modulation and Coding Scheme (MCS)) to be used by the mobile terminal for transmission.

[058] Allocation information is signaled to the UE through a scheduling grant, sent on the L1/L2 control channel. For simplicity, this channel can be called the uplink grant channel in the following. A 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 transport format that the UE has to use for the next uplink transmission. The shortest validity period is a subframe. Additional information may also be included in the grant message depending on the scheme selected. Only “per UE” grants are used to grant the right to transmit on UL-SCH (i.e., there are no “per EU per RB” grants). Therefore, the UE needs to distribute the allocated resources among the radio bearers according to some rules. Unlike HSUPA, there is no UE-based transport format selection. The eNB decides the transport format based on some information, for example, registered scheduling information and QoS information, and UE has to follow the selected transport format. In HSUPA, Node B assigns the maximum uplink resource, and the UE accordingly selects the actual transport format for data transmissions.

[059] Since scheduling of radio resources is the most important function in a shared channel access network to determine Quality of Service, there are several requirements that must be met by the UL to LTE scheduling scheme in order to enable effective QoS management. - Exhaustion of low priority services must be avoided; - Clean QoS differentiation for radio bearers/services must be supported by the scheduling scheme; - UL reporting must allow fine-grained buffer state reporting (e.g., per radio bearer or per radio bearer group) in order to allow the eNB programmer to identify which Radio Bearer/service the data should be sent to sent; - It must be possible to differentiate clean QoS between services from different users; - It must be possible to provide a minimum bit rate per radio bearer.

[060] As can be seen from the list above, an essential aspect of the LTE scheduling scheme is to provide mechanisms with which the operator can control the partitioning of its aggregate cell capacity among radio bearers of different QoS classes. A radio bearer's QoS class is identified by the QoS profile of the corresponding SAE bearer signaled from AGW to eNB, as described previously. An operator can then allocate a certain amount of its aggregate cell capacity to the aggregated traffic associated with radio bearers of a certain QoS class. The main objective of employing this class-based approach is to be able to differentiate the handling of packets which depend on the QoS class they belong to.

BUFFER STATUS REPORT/SCHEDULE REQUEST PROCEDURE FOR UPLINK SCHEDULE

[061] The usual mode of scheduling is dynamic scheduling, through downlink assignment messages for allocating downlink transmission resources and uplink grant messages for allocating uplink transmission resources; these are typically valid for specific single subframes. They are transmitted on the PDCCH using the UE's C-RNTI as previously mentioned. Dynamic programming is effective for service types where traffic has a bursty and dynamic rate, such as TCP.

[062] In addition to dynamic scheduling, persistent scheduling is defined, which allows radio resources to be semi-statically configured and allocated to a UE for a longer period of time than a subframe, thereby avoiding the need for specific downlink assignment messages or uplink grant messages over the PDCCH for each subframe. Persistent scheduling is useful for services such as VoIP, for which data packets are small in size, periodic, and semi-static. This way, the PDCCH overhead is significantly reduced compared to the dynamic programming case.

[063] Buffer State Reports (BSR) from the UE to the eNodeB are used to assist the eNodeB in allocating uplink resources, i.e., in uplink scheduling. For the downlink case, the eNB programmer is obviously aware of the amount of data to be distributed to each UE; However, for the uplink direction, since scheduling decisions are made in the eNB and the buffer for the data is in the UE data, BSRs have to be sent from the UE to the eNB in order to indicate the amount of data it needs. be transmitted via UL-SCH.

[064] There are primarily two types of Buffer State Reporting (BSR) MAC control elements defined for LTE: a long BSR (with four buffer size fields corresponding to LCG IDs 0 through 3) or a BSR short (with an LCG ID field and a corresponding buffer size field). The buffer size field indicates the total amount of data available across all logical channels of a logical channel group, and is indicated in the number of bytes encoded as an index of different buffer size levels (see also 3GPP TS 36.321 v 10.5.0 Chapter 6.1.3.1, incorporated herein by reference). Additionally, there is an additional type of Buffer State Report, for using truncated data, where the Buffer State Report is 2 bytes long.

[065] Which of the short or long BSR is transmitted by the UE depends on the transmission resources available in a transport block, how many groups of 30 logical channels have non-empty buffers, and whether a specific event is triggered in the UE. The long BSR reports the amount of data for four logical channel groups, while the short BSR reports the amount of buffered data for only the highest logical channel group.

[066] The reason for introducing the logical channel group concept is that although the UE may have more than four logical channels configured, reporting the buffer state for each individual logical channel would cause a lot of signaling overhead. Therefore, the eNB assigns each logical channel to a logical channel group; Preferably, logical channels with the same/similar QoS requirements should be allocated within the same logical channel group.

[067] A BSR can be triggered, as an example, for the following events: - Whenever data arrives on a logical channel, which has a higher priority than logical channels, whose buffer is non-empty; - Whenever data becomes available for any logical channel, when there was previously no data available for transmission; - Whenever the BSR retransmission time expires; - Whenever the BSR periodic report is due, that is, the BSR periodic timer; - Whenever there is a free space in a transport block that can accommodate a BSR.

[068] To be robust against transmission failures, there is a BSR retransmission mechanism defined for LTE; The BSR retransmission timer is started or reset whenever an uplink lease is reset. If no uplink lease is received before the BSR retransmission timer expires, another BSR is triggered by the UE.

[069] If the UE does not have uplink resources allocated to include a BSR in the transport block (TB) when a BSR is triggered, the UE sends a scheduling request (SR) on the Physical Uplink Control Channel (PUCCH), if configured. For the case that there are no D-SR resources (dedicated programming request) in the configured PUCCH, the UE will initiate the Random Access Procedure (RACH procedure) in order to request UL-SCH resources to transmit information from BSR to eNB . However, it should be noted that the UE will not trigger SR transmission in case a periodic BSR has to be transmitted.

[070] Additionally, an enhancement to SR transmission has been introduced for a specific scheduling mode where resources are persistently allocated with a defined periodicity in order to save L1/2 control signaling overhead for transmission grants, which is referred to as semi-persistent programming (SPS). An example for a service, which was primarily considered for semi-persistent programming, is VoIP. Every 20 ms, a VoIP packet is generated in the Codec during a talkspurt. Therefore, eNB can allocate uplink or respectively downlink resource persistently every 20 ms, which could then be used for transmitting VoIP packets. In general, SPS is beneficial for services with predictable traffic behavior, i.e. rate constant bit, packet arrival time is periodic. In case the SPS is configured for the uplink direction, the eNB can turn off SR triggering/transmission for certain configured logical channels, i.e., BSR triggering due to the arrival of data on those specific configured logical channels will not trigger an SR. The motivation for this type of improvement is related to an SR for those logical channels that will use the semi-persistently allocated resources (logical channels that carry VoIP packets) is of no value for eNB programming and therefore should be avoided.

[071] More detailed information regarding the BSR and, in particular, its activation is explained in 3GPP TS 36.321 V10.5 in Chapter 5.4.5 incorporated here by reference.

LOGICAL CHANNEL PRIORITIZATION

[072] The UE has an uplink rate control function that manages the sharing of uplink resources between radio bearers. This uplink rate control function is also referred to as the logical channel prioritization procedure below. The Logical Channel Prioritization (LCP) procedure is applied when a new transmission is performed, that is, the transport block needs to be generated. One proposal for capacity allocation has been to assign resources to each bearer, in order of priority, until each has received an allocation equivalent to the minimum data rate for that bearer, after which any additional capacity is assigned to the bearer in order of priority. , for example.

[073] As will become evident from the description of the LCP procedure given below, the implementation of the LCP procedure that resides in the UE is based on the token bucket model, which is well known in the IP world. The basic functionality of this model is as follows. Periodically, at a certain rate, a signal, which represents the right to transmit a quality of data, is added to the bucket. When the UE is granted resources, it is allowed to transmit data up to the amount represented by the number of signals in the bucket. When transmitting data, the UE removes the number of signals equivalent to the amount of data transmitted. In case the bucket is full, any additional signals are discarded. For signal addition, it can be assumed that the repeat period for this process could be every TTI, but could easily be extended so that a signal is only added every second. Basically, instead of every 1 ms a signal is added to the bucket, 1000 signals could be added every second. Next, the logical channel prioritization procedure that is used in Rel-8 is described.

[074] More detailed information regarding the LCP procedure is explained in 3GPP TS 36.321 V8 in Chapter 5.4.3.1, incorporated here by reference.

[075] RRC controls the scheduling of uplink data by signaling each logical channel: priority where an increase in priority value indicates a lower priority level, prioritisedBitRate which sets the Prioritized Bit Rate (PBR), bucketSizeDuration which sets the Duration Bucket Size (BSD). The idea behind prioritized bit rate is to support for each carrier, including low priority non-GBR carriers, a minimum bit rate in order to avoid potential burnout. Each bearer must at least get enough resources in order to achieve the prioritized bit rate (PRB).

[076] The UE must maintain a variable Bj for each logical channel j. Bj must be initialized to zero when the related logical channel is established and incremented by the duration of the PBR x TTI product for each TTI, where PBR is the Prioritized Bit Rate of logical channel j. However, the value of Bj can never exceed the bucket size, and if the value of Bj is greater than the bucket size of logical channel j, it must be set to the bucket size. The bucket size of a logical channel is equal to PBR x BSD, where PBR and BSD are configured by the upper layers.

[077] The UE must perform the following Logical Channel Prioritization procedure when a new transmission is performed: - The UE must allocate resources to the logical channels in the following steps: - Step 1: All logical channels with Bj > 0 are resources allocated in a descending order of priority. If the PBR of a radio bearer is set to “infinity”, the UE must allocate resources to all data that is available for transmission on the radio bearer before finding the PBR of the low-end radio bearer(s). priority; - Step 2: The UE must decrease Bj by the total size of MAC SDUs served to logical channel j in Step 1. It should be noted at this point that the value of Bj can be negative. - Step 3: If none of the resources remain, all logical channels are served in a strict descending priority order (regardless of the value of Bj) until either the data for that logical channel or the UL grant is exhausted, whichever comes first . Logical channels configured with equal priority must be served equally. - The UE must also follow the rules below through the above programming procedures: - The UE must not segment an RLC SDU (or partially transmitted SDU or retransmitted RLC PDU) if the total SDU (or partially transmitted SDU or retransmitted RLC PDU) is fit in the remaining resources; - if the UE segments an RLC SDU from the logical channel, it must maximize the segment size to fill the lease as much as possible; - UE must maximize data transmission.

[078] For the Logical Channel Prioritization procedure, the UE must take into account the following relative priority in descending order: - MAC control element for C-RNTI or UL-CCCH data; - MAC control element for BSR, with the exception of BSR included for padding; - MAC control element for PHR; - Data from any Logical Channel, except UL-CCCH data; - MAC control element for BSR included for backfilling.

[079] For the case of carrier aggregation, which is described in a later section, when the UE is requested to transmit multiple MAC PDUs in a TTI, steps 1 to 3 and the associated rules may be applied either to each grant independently or for the sum of the concessions’ capacities. Also, the order in which grants are processed is left up to UE implementation. It is up to the UE implementation to decide in which MAC PDU a MAC control element is included when the UE is requested to transmit multiple MAC PDUs in a TTI.

UPLINK POWER CONTROL

[080] Uplink transmission power control in a mobile communications system serves an important purpose: it balances the need for sufficient transmitted power per bit to achieve the requested Quality of Service (QoS), against the needs to minimize interference. for other users of the system and to maximize the battery life of the mobile terminal. In achieving this purpose, the role of Power Control (PC) becomes decisive to provide the requested SINR while at the same time controlling the interference caused to neighboring cells. The idea of classical uplink PC schemes is that all users are received with the same SINR, which is known as total compensation. As an alternative, 3GPP adopted for LTE the use of Fractional Power Control (FPC). This new functionality causes users with higher path loss to operate at a lower SINR request, so they are more likely to generate less interference to neighboring cells.

[081] Detailed power control formulas are specified in LTE for the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH) and the Sound Reference Signals (SRSs) (section 5.1 in TS36.213 ). The formula for each of these uplink signals follows the same basic principles; in all cases, they can be considered as a sum of two main terms: a basic open-cycle operating point derived from static or semi-static parameters by the eNodeB, and a dynamic offset updated from subframe to subframe.

[082] The basic open cycle operating point for transmit power per resource block depends on several factors including intercell interference and cell load. It can be further broken down into two components, a semi-static base level P0, further comprised of a common power level for all UEs in the cell (measured in dBm) and a UE-specific offset and path loss compensation component. . The dynamic power shift per resource block can also be further broken down into two components, a component dependent on the MCS used and explicit Transmitter Power Control (TPC) commands.

[083] The MCS-dependent component (referred to in LTE specifications as ^TF, where TF stands for “Transport Format”) allows the power transmitted by RB to be adapted according to the data rate of transmitted information.

[084] The other component of dynamic displacement is UE-specific TPC commands. These can operate in two different modes: cumulative TPC commands (available for PUSCH, PUCCH and SRS) and absolute TPC commands (available for PUSCH only). For PUSCH, the transition between these two modes is configured semi-statically for each UE through RRC signaling - that is, the mode cannot be changed dynamically. With cumulative TPC commands, each TPC command signals a power step relative to the previous level.

POWER RANGE REPORT

[085] In order to assist the eNodeB in scheduling the uplink transmission resources for different UEs in an appropriate manner, it is important that the UE can report its available power range to the eNodeB.

[086] The eNodeB can use the power range reports to determine how much more uplink bandwidth per subframe a UE is capable of using. This helps to avoid allocating uplink transmission resources to UEs that are unable to use them in order to avoid a waste of resources.

[087] The range of the power range report is +40 to -23 dB. The negative part of the range allows the UE to signal to the eNodeB that it has received a UL grant that would request more transmit power than the UE has available. This would allow the eNodeB to reduce the size of a subsequent grant, thereby freeing up transmission resources to allocate to other UEs.

[088] A power range report can only be sent in subframes where a UE has a UL grant. The report refers to the subframe in which it is submitted. Several criteria are defined to trigger a power range report. These include: - A significant change in estimated path loss since the last power range report. - More than one configured time has elapsed since the previous power range report. - More than a configured number of closed-loop TPC commands have been implemented by me.

[089] The eNodeB can configure parameters to control each of these drives depending on the system load and the requirements of its programming algorithm. To be more specific, RRC controls the power range reporting by setting two timers periodicPHR-Timer and prohibitPHR-Timer, and by signaling dl-PathlossChange which configures the change in the measured downlink lost path to trigger a power range report. power.

[090] The power range report is sent as a MAC Control Element. It consists of a simple octet where the highest two bits are reserved and the lowest six bits represent the dB values mentioned above in 1 dB steps. The structure of the MAC Control Element is shown in Figure 7.

[091] The PH of the UE power range valid for subframe is defined by:

[092] The power range must be rounded to the nearest value in the range [40; -23] dB in 1 dB steps.

[093] Pcmax, the maximum UE Transmit power (Tx power) is a value chosen by the UE in the given range of PCMAX_L and PCMAX_H.

[094] PCMAX_L ≤ PCMAX ≤ PCMAX_H, where

[095] PCMAX_L = MIN {PEMAX- ∆Tc, Ppowerclass - MPR - AMPR - ∆TC}, and

[096] PCMAX_H = MIN {PEMAX, Ppowerclass};

[097] and where PEMAX is the value signaled by the network.

[098] MPR is a power reduction value used to control the adjacent channel leakage power ratio (ACLR) associated with various modulation schemes and the transmission bandwidth.

[099] A-MPR is the maximum additional power reduction. It is band specific and is applied when configured by the network. Therefore, Pcmax is the specific implementation of UE and, therefore, not known as eNB.

[0100] More detailed information regarding ΔTc is specified in 3GPP TS TS36.101, Version 12.0.0, section 6.2.5, incorporated herein by reference.

LTE DEVICE-TO-DEVICE (D2D) PROXIMITY SERVICES

[0101] Proximity-based applications and services represent an emerging social-technological trend. Areas identified include services related to commercial services and Public Safety that would be of interest to operators and users. The introduction of a Proximity Services (ProSe) capability in LTE would allow the 3GPP industry to serve this developing market, while also serving the urgent needs of several Public Safety communities that are jointly committed to LTE.

[0102] Device-to-device (D2D) communication is a technology component for LTE-rel.12. Device-to-device (D2D) communication technology enables D2D as an underlay to the cellular network to increase spectral effectiveness. For example, if the cellular network is LTE, all physical data carrying channels use SC-FDMA for D2D signaling. In D2D communication, user equipments (UEs) transmit data signals to each other over a direct link using cellular resources rather than through the Base Station. A possible scenario in a D2D-compatible communication system is shown in Figure 9.

D2D COMMUNICATION IN LTE

[0103] “D2D communication in LTE” is focusing on two areas: Discovery and Communication, while this invention is mainly related to the communication part. Therefore, the following technical background is focusing on the communication part.

[0104] Device-to-device (D2D) communication is a technology component for LTE-A. In D2D communication, UEs transmit data signals to each other over a direct link using cellular resources instead of through the BS. D2D users communicate directly while remaining controlled under the BS, that is, at least when in coverage of an eNB. Therefore, D2D can improve system performances by reusing cellular resources.

[0105] It is assumed that D2D operates in uplink LTE spectrum (in the case of FDD) or uplink subframes of cell donation coverage (in the case of TDD except when outside coverage). Additionally, D2D transmission/reception does not use full duplex on a given carrier. From the perspective of the UE, on a given carrier, D2D signal reception and LTE uplink transmission do not use full duplex, that is, simultaneous D2D signal reception and LTE UL transmission are not possible.

[0106] In D2D communication when UE1 has a transmitting role (transmitting user equipment), UE1 sends data and UE2 (receiving user equipment) receives it. UE1 and UE2 can change their transmitting and receiving role. The transmission from UE1 may be received by one or more UEs as UE2.

[0107] Regarding User plane protocols, the following is the content of the agreement [3GPP TS 36.843vers. 12.0.0 section 9.2] from the D2D communication perspective is reported: - PDCP: • 1:M D2D propagation communication data (i.e. IP packets) should be handled as normal user plane data. • Head compression/decompression in PDCP is applicable for 1:M D2D propagation communication. • U-mode is used for head compression in PDCP for D2D propagation operation for public safety; • RLC: • RLC UM is used for 1:M D2D propagation communication. • Segmentation and Reassembly are supported in L2 by RLC UM. • A receiving UE needs to maintain at least one RLC UM entity per transmit peer UE. • An RLC UM receiving entity does not need to be configured prior to receipt of the first RLC UM data unit. • So far, no need has been identified for RLC AM or RLC TM for D2D communication for user plane data transmission. • MAC: • No HARQ response is assumed for 1 : M D2D propagation communication. • The receiving UE needs to know a source ID in order to identify the RLC UM receiving entity. • The MAC head comprises a target L2 ID that allows packets to be filtered at the MAC layer. • The target L2 ID can be a propagation, groupcast or unicast address. • Groupcast/Unicast L2: A target L2 ID carried in the MAC header would allow discarding a received RLC A PDU even before distributing it to the RLC receiver entity. • Broadcast L2: A receiving UE would process all RLC PDUs received from all transmitters and is intended to reassemble and distribute IP packets to the upper layers. • MAC subheader contains LCIDs (to differentiate multiple logical channels). • At least Multiplexing/demultiplexing, priority serving and padding are useful for D2D.

RESOURCE ALLOCATION

[0108] Resource allocation for D2D communication is under discussion and is described in its present form in 3GPP TS 36.843, version 12.0.0, section 9.2.3, incorporated herein by reference.

[0109] From the perspective of a transmitting UE, a UE can operate in two modes for resource allocation: • Mode 1: eNodeB or Release-10 Relay Node schedules the exact resources used by a UE to transmit direct data and direct control information • Mode 2: a UE alone selects resources from resource sets to transmit direct data and direct control information

[0110] The UE capable of D2D communication must support at least Mode 1 for indoor coverage. The UE capable of D2D communication must support Mode 2 for at least in-coverage and/or out-of-coverage edge UEs that need to be aware of a resource set (time/frequency) for reception of the communication D2D.

[0111] All UEs (Mode 1 (“scheduled”) and Mode 2 (“standalone”) are provided with a set of resources (time and frequency) in which they attempt to receive scheduling assignments.

[0112] In Mode 1, a UE requests transmission resources from an eNodeB. The eNodeB schedules transmission resources for transmission of the assignment(s) and scheduling data. • The UE sends the scheduling request (D-SR or RA) to the eNodeB followed by a BSR based on which the eNodeB can determine that the UE intends to perform a D2D transmission as well as the required amount of resources. • In Mode 1, the UE needs to be RRC Connected in order to transmit D2D communication.

[0113] For Mode 2, UEs are provided with a set of resources (time and frequency) from which they choose resources to transmit D2D communication.

[0114] Figure 8 schematically illustrates the Overlay (LTE) and Underlying (D2D) transmission and/or reception capabilities. The eNodeB controls whether the UE can apply Mode 1 or Mode 2 transmission. Once the UE knows its resources, where it can transmit (or receive) D2D communication, it uses the corresponding resources only for corresponding transmission/reception. In the example in figure 8, D2D subframes will only be used to receive or transmit D2D signals. Since the UE as a D2D device would operate in Half Duplex mode, it can receive or transmit the D2D signals at any point of time. Similarly, in the same figure, the other subframes can be used for LTE transmissions and/or reception (overlay).

[0115] D2D discovery is the procedure/process of identifying other D2D capable and interested devices in the vicinity. For this purpose, D2D devices that need to be discovered would send some discovery signals (on certain network resources) and the receiving UE interested in said discovery signal will come to know of such transmitting D2D devices. Channel 8 of 3GPP TS 36.843 describes the available details of D2D Discovery mechanisms. In the following, two types of discovery procedures are defined: • Type 1: a discovery procedure where resources for discovery signal transmission are allocated on a non-UE specific basis • Type 2: a discovery procedure where resources for discovery signal transmission are allocated on a UE-specific basis: • Type 2A: Resources are allocated for each specific transmission time of discovery signals • Type 2B: Resources are allocated semi-persistently for discovery signal transmission.

[0116] Current discussions on programming schemes for allocating D2D resources focus on how to incorporate D2D-related SR/BSR signaling into the LTE-A system, that is, whether the LTE BSR/SR mechanism and resources, e.g., D-SR in PUCCH or PRACH resources, are reused for D2D communication purposes. According to a scheme actually being considered, the eNodeB configures contention-based resources within the D2D subframe or region to carry out the scheduling procedure. In other words, the Scheduling Request (SR) and/or a Buffer State Report (BSR) related to D2D transmissions are sent to the eNodeB on dedicated resources in a dedicated subframe for D2D transmissions. Therefore, the user equipment must only use resources within the D2D subframe/region for all D2D-related transmissions, including messages to perform the programming procedure, i.e., the SR and/or BSR.

[0117] This approach has the disadvantage that radio resource management can become very complex when eNodeB has to support resources such as resources for a dedicated Scheduling Request (D-SR) and RACH resources (contention-based SR). ) within the D2D subframe or region.

[0118] As a consequence, these resources also need to be signaled to all available D2D UEs and cannot be used for D2D data discovery transmission, thus leading to loss of data transmission performance. Additionally, another modification to the LTE standard (RAN 4) will be requested if new PUCCH resources need to be configured within the D2D subframes.

[0119] Finally, the eNodeB would be requested to monitor and/or receive D2D resources in order to receive D-SR/PRACH/BSR from the D2D UE. This solution would therefore lead to an overload of the eNodeB.

SUMMARY OF THE INVENTION

[0120] In order to integrate D2D communication into the LTE system, some aspects of LTE systems, such as procedures, spectrum for data communication and the like are resumed. As an example, in uplink communication, the uplink spectrum of the LTE system is also used for device-to-device communication.

[0121] The objective of the invention is to develop a method and system capable of integrating device-to-device (D2D) communication into the LTE system in a manner that requires the fewest possible changes to the current system. More specifically, the present invention aims to develop a system and method that incorporates the scheduling request and the Buffer State Support (BSR) procedure for device-to-device communications in an LTE system.

[0122] The objective is solved by the subject of independent claims. The advantageous realizations are subject to the dependent claims.

[0123] According to a first aspect of the present invention, a transmitting user equipment capable of integrating D2D, which needs to transmit data to a receiving user equipment via a direct link data channel, uses the services of the eNodeB in order to have resources allocated to transmit said data. For this purpose, the UE sends to the eNB scheduling information using resources in a dedicated subframe for standard uplink communication through the eNodeB, instead of using resources in the dedicated subframe for D2D data transmission. In order to allow the eNB to distinguish whether the received scheduling request is to allocate resources to transmit data over the direct link channel or over the eNB, the UE may also send, along with the scheduling information, identification information associated with the information of programming.

[0124] Advantageously, the user equipment can send a buffer status report to the eNodeB on the uplink data channel, e.g., the PUSCH, and in a frame used for transferring LTE data and scheduling messages.

[0125] According to a further aspect of the invention, in the case where resources are not available for the UE to send the scheduling information, before sending the scheduling information, the UE may send to the eNB a scheduling request to request resource allocation for the uplink data channel to send the scheduling information to the eNB. Transmission of the scheduling request can be triggered by two events. The first trigger condition includes the presence of data to be transmitted in the transmission buffer of the transmission user equipment. The second trigger condition provides that the data in the transmission buffer changes by a predefined amount from the transmission of the last scheduling information. Advantageously, the data in the transmission buffer may increase by a predefined amount with respect to the amount of data in the transmission buffer at the time the last programming information was triggered or sent. According to a further advantageous implementation, the second trigger condition can alternatively be checked if the data in the transmission buffer exceeds a predefined threshold.

[0126] According to the first aspect described above, a transmitting user equipment is provided, which is adapted to transmit data to a receiving user equipment via a direct link connection in a communication system. The transmission user equipment is further adapted to request resources in the communication system and comprises a transmission unit configured to transmit to a base station direct link scheduling information for allocating resources for transmitting data to the transmission user equipment. reception via direct dial connection. The forward link scheduling information is transmitted to the base station on an uplink data channel to transmit data to the base station.

[0127] Additionally, or alternatively, according to a further development, in the transmission user equipment, direct link programming information is transmitted within a MAC element control. The transmission unit is further adapted to transmit to the base station on the uplink data channel an identification number associated with direct link programming information, the identification number identifying said MAC control element. Advantageously, according to a further development, the MAC control element for direct link scheduling information is stored in a data unit further containing LTE logical channel data and/or uplink scheduling information for LTE traffic. LTE. The data unit may be an LTE MAC Protocol Data Unit including a D2D MAC CE and LTE data packets (MAC SDUs) and/or LTE MAC CE.

[0128] Additionally, or alternatively, the transmitting user equipment further comprises a transmission buffer adapted to temporarily store data to be transmitted to the receiving user equipment via the direct link connection, wherein the transmission information direct link programming comprises a value associated with the data in the transmission buffer.

[0129] Additionally, or alternatively, the forward link scheduling information may have a higher priority than the uplink scheduling information transmitted to the base station on the uplink data channel, the uplink scheduling information being used to resource allocation for uplink data transmission over the base station. Advantageously, the forward link scheduling information and the uplink scheduling information are transmitted within a MAC Protocol Data Unit for LTE transmission.

[0130] Additionally, or alternatively, in direct link programming information, the value associated with the data stored in the transmit buffer may be the total amount of bits/bytes to be transmitted to the receiving user equipment via the wire connection. direct link.

[0131] Additionally, or alternatively, the direct link programming information further includes information on the type of data to be transmitted over the direct link connection.

[0132] According to a further aspect of the invention described above, the transmission user equipment may further comprise, in addition to or as an alternative to the elements described above, a memory adapted to store a first trigger condition and a second trigger condition. . The first trigger condition requires the arrival of new data in the transmission buffer, wherein the new data is intended to be transmitted to the receiving user equipment via the forward link connection. The second trigger condition requires a value associated with the data in the transmit buffer to change through a predefined value. The transmission user equipment further includes a processing unit adapted to determine whether the first trigger condition is met and whether the first trigger condition is met to determine whether the second trigger condition is met. The transmission unit is further adapted to transmit a direct link scheduling request to request allocation of uplink resources to transmit the direct link scheduling information to the base station, in which case the processing unit has determined that the second trigger condition was met.

[0133] Advantageously, the amount of data in the transmission buffer can change by a predefined amount with respect to an amount of data in the transmission buffer at the time before the scheduling information is sent to the base station. Alternatively, a change in the amount of data in the transmission buffer may be checked, if the amount of data in the transmission buffer exceeds a certain threshold.

[0134] Additionally, or alternatively, the direct link scheduling request is transmitted to the base station on an uplink control channel or on a random access channel. Furthermore, the value associated with the data in the transmission buffer may be the amount of data in said transmission buffer, and transmission of forward link scheduling information is triggered if said data in said transmission buffer is changed by a default value since a previous transmission of direct connection programming information.

[0135] According to a further aspect of the invention described above, a communication method is provided for requesting resources through a transmission user equipment in a communication system, wherein data is to be transmitted from the transmission user equipment to a receiving user equipment via a direct connection. The method comprises the steps of transmitting, at the transmitting user equipment, to a base station direct link scheduling information for allocating resources for transmitting data to the receiving user equipment via the direct link connection. Direct link scheduling information can be transmitted to the base station on an uplink data channel to transmit data to the base station.

[0136] Additionally, or alternatively, the forward link scheduling information is transmitted within a MAC control element, and the step of transmitting the forward link scheduling information comprises transmitting to the base station on the forward link data channel. uplink, an identification number associated with forward link programming information, said identification number identifying said MAC control element. Advantageously, according to a further development, the MAC control element for the forward link scheduling information is stored in a MAC data unit potentially further containing the LTE logical channels and/or uplink scheduling information for LTE traffic. The data unit may be an LTE MAC Protocol Data Unit.

[0137] Additionally, or alternatively, the forward link scheduling information comprises a value associated with data stored in a transmission buffer in the transmission user equipment, the transmission buffer being adapted to temporarily store the data to be transmitted to receiving user equipment through direct connection.

[0138] Additionally, or alternatively, the forward link scheduling information has a higher priority than the uplink scheduling information transmitted to the base station on the uplink data channel, the uplink scheduling information being used for resource allocation for uplink data transmission over the base station.

[0139] Additionally, or alternatively, in the direct link programming information, the value associated with the data stored in the transmission buffer is the total bit quantity to be transmitted to the receiving user equipment via the direct link connection.

[0140] Additionally, or alternatively, the direct link programming information further includes information on the type of data to be transmitted over the direct link connection.

[0141] According to a further aspect, the method, as described above, comprises defining a first trigger condition and a second trigger condition. The first trigger condition requires the arrival of new data in the transmission buffer, wherein said new data must be transmitted to the receiving user equipment via the forward link connection. The second trigger condition requires a value associated with the data in the transmit buffer to change through a predefined value. The method further comprises determining, at the transmission user equipment, whether the first trigger condition is met, and whether the first trigger condition is met, determining by the transmission user equipment whether the second trigger condition is met. In the transmission user equipment, a forward link scheduling request to request allocation of uplink resources to transmit the forward link scheduling information is transmitted to the base station, in which case the processing unit has determined that the second trigger condition was met.

[0142] Additionally, or alternatively, the direct link scheduling request is transmitted to the base station on an uplink control channel or on a random access channel.

[0143] Furthermore, the value associated with the data in the transmission buffer may be the amount of data in said transmission buffer and the transmission of forward link control information is triggered if said data in said transmission buffer is changed. by a predefined value since a previous transmission of direct link control information.

[0144] Advantageously, data transmitted via the direct link connection by the transmitting user equipment and in accordance with the above method is directly sent to the receiving user equipment bypassing the mobile station.

[0145] Advantageously, the transmission unit and the above method enable the transmission of data to the receiving user equipment in a dedicated resource for data transmission via direct link communication, and transmit data about the base station in a dedicated resource for transmitting uplink data to the base station.

BRIEF DESCRIPTION OF FIGURES

[0146] In the following, the invention is described in more detail with reference to the attached figures and drawings. Similar or corresponding details in the figures are marked with the same reference numerals.

[0147] Figure 1 shows an exemplary architecture of a 3GPP LTE system;

[0148] Figure 2 shows an exemplary overview of the general E-UTRAN architecture of 3GPP LTE;

[0149] Figure 3 shows exemplary subframe boundaries on a downlink component carrier as defined for 3GPP LTE (Release 8/9);

[0150] Figure 4 shows an exemplary downlink resource grid of a downlink slot as defined for 3GPP LTE (Release 8/9);

[0151] Figures 5 and 6 show the Layer 2 structure of 3GPP LTE-A (Release 10) with carrier aggregation enabled for the downlink and uplink, respectively;

[0152] Figure 7 shows the structure of a MAC Control Element;

[0153] Figure 8 is a schematic illustration showing overlay (LTE) and underlying (D2D) transmission and reception capabilities in D2D subframes;

[0154] Figure 9 is a schematic illustration showing a system including D2D capable user equipment;

[0155] Figure 10 is a schematic drawing illustrating the messages exchanged between the transmission user equipment (UE1) and the base station (eNB) for programming purposes and the data exchanged between the transmission user equipment (UE1) and a receiving user equipment (UE2), according to a first embodiment of the present invention;

[0156] Figure 11 illustrates a composition of a MAC Protocol Data Unit (PDU) according to an implementation of the method and programming system according to the invention;

[0157] Figure 12 is a schematic drawing illustrating the messages exchanged between the transmission user equipment (UE1) and the base station (eNB) for programming purposes and the data exchanged between the transmission user equipment (UE1) and a receiving user equipment (UE2), according to a second embodiment of the present invention;

[0158] Figure 13 is a flowchart illustrating the messages exchanged between the transmission user equipment (UE1) and the base station (eNB) for programming purposes and the data exchanged between the transmission user equipment (UE1) and a receiving user equipment (UE2), according to a second embodiment of the present invention;

[0159] Figure 14 is a flowchart describing the reception of D2D Discovery Signals;

[0160] Figure 15 is a schematic drawing illustrating Neighbor Discovery.

DETAILED DESCRIPTION OF THE INVENTION

[0161] The following paragraphs will describe various embodiments of the invention. For exemplary purposes only, most of the embodiments are outlined in relation to a radio access scheme in accordance with 3GPP LTE (Release 8/9) and LTE-A (Release 10/11/12) mobile communication systems, partially discussed in the Technical History section above. It should be noted that the invention may be advantageously used, for example, in a mobile communication system such as 3GPP LTE-A communication systems (Release 10/11/12) as described in the Technical History section above, but the invention does not is limited for its use in these particular exemplary communication networks.

[0162] The term “direct link” used in the claims and description should be understood as a communication link (communication channel) between two D2D user equipment, which allows data exchange directly without the involvement of the network. In other words, a communication channel is established between two user devices in the communication system, which are close enough to directly exchange data, bypassing the eNodeB (base station). This term is used in contrast to “LTE link” or “LTE traffic (uplink)”, which instead refers to data traffic between user equipment managed by the eNodeB.

[0163] The term “transmission user equipment” used in the claims and description is to be understood as a mobile device capable of transmitting and receiving data. The adjective of transmission only means to clarify a temporary operation. The term is used in contrast to “receiving user equipment”, which refers to a mobile device temporarily performing the operation of receiving data.

[0164] The term “new data” used in the claims and description is to be understood as data arriving/being stored in the transmission buffer that was not previously there. This data (data packets) is received from a higher layer, for example IP layer, and placed in the transmission buffer. This term is used in contrast to “old data”, referring to data that is kept in the transmission buffer as long as the transmission protocol guarantees that this data is correctly received on the receiving side.

[0165] The term “arrival”, used in the claims and description with respect to data and transmission buffers, is to be understood as that data which is to be transmitted through the “inputs” of the user equipment, or “be put into” or “be temporarily stored in” the transmission buffer of the corresponding logical channel for transmission.

[0166] In the following, various embodiments of the invention will be explained in detail. The explanations should not be understood as limiting the invention, but as a simple example of the embodiments of the invention to better understand the invention. One skilled in the art should be aware that the general principles of the invention, as set forth in the claims, can be applied to different scenarios and in ways that are not explicitly described here. Correspondingly, the following scenario assumed for explanatory purposes of the various embodiments should not limit the invention as such.

[0167] The present invention is mainly directed to the programming procedure for device-to-device (D2D) communication in LTE systems. A D2D capable user equipment can operate in two modes for resource allocation. According to a first mode of operation (mode 1), the eNodeB programs the exact resources that are used by the transmitting user equipment to transmit data to a receiving user equipment via a direct link channel. Specifically, the broadcast user equipment sends a request for resource allocation to the eNodeB and, based on the allocation request, the latter schedules the exact resources needed by the broadcast user equipment to transmit data directly to the broadcast user equipment. reception (programmed operation mode).

[0168] The second mode of operation (mode 2) is a collision-based approach. According to this approach, each user equipment was provided with a set of D2D time/frequency resources used for D2D communication, which is also referred to as a resource set. The transmitting user equipment may autonomously select from the resource pool resources to transmit data and control information directly to the receiving user equipment(s) over the direct link communication channel. (autonomous operating mode).

[0169] In scheduled operation mode (mode 1), scheduling information is transmitted to the eNodeB on an uplink data channel. The scheduling information may be a Buffer State Report on a MAC BSR Control Element, which is sent to the eNodeB on a Physical Uplink Shared Control Channel (PUSCH).

[0170] A first embodiment of the invention will be explained in connection with Figure 10, which illustrates the messages exchanged between the transmitting user equipment (UE1) and the base station (eNB) for programming purposes and the data exchanged between the transmitting user equipment (UE1) and a receiving user equipment (UE2). The transmitting user equipment (UE1) requests resources by transmitting buffer status information to the eNodeB over the LTE uplink data channel (PUSCH) and transmits data to the receiving user equipment via a direct link communication. Although buffer state information is related to the transmission of D2D data, that is, D2D carrier data that is sent over the direct link (also referred to as PC5 interface), the transmission of buffer state information is transmitted in a resource of LTE uplink time/frequency not in a D2D subframe, respectively time/frequency resource. Specifically, once the eNB receives the BSR, it will allocate resources from the time/frequency resources that are reserved for D2D data communication, e.g. direct link channel, to allow the transmission user equipment (UE1 ) transmit data to the receiving user equipment (UE2). It should be noted that the resource allocation for D2D data communication respectively, the grant that allocates the D2D transmission resources may be different compared to an LTE uplink grant. For example, the D2D resource could be allocated for a longer term, not just to a TTI. In general, granting of D2D resource allocations is expected to be using a new downlink control format (DCI). The DCI can also be mixed with a new R-NTI, that is, a D2D RNTI in contrast to the C-RNTI that is used for LTE uplink leases. If the granted resources are not sufficient to transmit all the data to the receiving user equipment (UE2), the eNB will successively grant resources over the forward link channel until the data has been completely transmitted by the transmitting user equipment (UE1 ) to the receiving user equipment (UE2). In other words, once resource allocation has been granted to the transmitting user equipment, the transmitting user equipment (UE1) and the receiving user equipment (UE2) can communicate with each other without involvement, that is, bypassing,the network. There is a direct communication channel between the two mobile stations. The data is thus first sent to the eNodeB using uplink resources, for example in PUSCH, and then sent to the eNodeB back via the LTE core network to the user equipment.

[0171] As can be seen in the diagram described in Figure 10, the scheduling request procedure can be viewed as regular LTE traffic, in which the transmission user equipment (UE1) contacts the eNodeB in order to request allocation of resources to transmit data stored in a data buffer or transmit to user equipment (not shown), i.e. data stored to D2D bearers. After that, once the eNodeB has assigned D2D time/frequency resources to transmit data, the user equipment starts transmitting data on the D2D resources, i.e. also referred to as direct link data channel. From that point in time, communication between the transmitting user equipment (UE1) and the receiving user equipment (UE2) will occur without mediating, i.e. bypassing, the eNodeB.

[0172] Alternatively, or in addition, a scheduling request may be transmitted via PUCCH resources allocated by the eNB, i.e. also referred to as a dedicated scheduling request (D-SR), or via the use of a RACH procedure. If not otherwise stated, in the following it will be assumed that such PUCCH resources, which are typically allocated periodically by the eNB, are available to the UE to transmit the scheduling request as soon as it is triggered; nevertheless, the invention is also applicable when it instead uses a RACH procedure. A dedicated scheduling request is usually one bit long, and the corresponding periodic PUCCHs allow transmitting the scheduling request, but not enough to transmit additional data such as the buffer status report or actual transmit buffer data. As described in the technical background section on LTE, a scheduling request is triggered for the case where a buffer state report has been triggered but there are no PUSCH resources available for transmitting the buffer state report. In other words, the purpose of the scheduling request is to ask the eNB to allocate PUSCH resources so that the UE could transmit the buffer state report which, in turn, allows the eNB to allocate suitable resources for transmitting the uplink data.

[0173] According to an embodiment of the invention, the D2D-enabled transmitting UE transmits a scheduling request (SR) on the PUCCH (D-SR) or performs the RACH procedure (contention-based scheduling request) where there is a Triggered buffer state reporting for D2D carriers, for example, when new data arrives for a D2D carrier. This scheduling request is transmitted on a regular LTE uplink time/frequency resource, that is, not on a time/frequency resource reserved for D2D. Upon receipt of this scheduling request, the eNB will allocate PUSCH resources to the D2D transmission UE. The D2D transmitting UE will in turn transmit the D2D-related buffer state information within these PUSCH resources, as already described above. Based on the detailed buffer state information, the eNB will allocate D2D time/frequency resources for D2D data communication. For allocation of PUSCH resources upon receipt of scheduling request, the regular LTE uplink grant/DCI procedure, i.e., uplink grant that is addressed to the C-RNTI timing relationship, PDCCH/PUSCH, is used . As mentioned above, the second uplink grant/resource allocation, i.e., having received the D2D-related buffer state information, may use a different resource allocation format/DCI, e.g., addressed to a D2D RNTI .

[0174] A more detailed description of the triggering of the programming request will be given below with reference to figure 12.

[0175] D2D capable user equipment (not shown) is adapted to send data on both the LTE uplink data channel and the direct communications data channel reserved for D2D communications. For this purpose, some subframes, respectively time/frequency resources, will be reserved for LTE uplink traffic, while other subframes, respectively time/frequency resources, are reserved for D2D transmission, i.e., this could be discovery signaling. of D2D and/or D2D data communication. Preferably, a predefined time slot will be allocated in each subframe in an alternative manner following a TDM scheme. As an example, very long periods of time can be allocated to signals that require more resources, by reserving more consecutive time slots for one of the two types of subframes mentioned above, while reducing the period of time allocated to signals that require less. resources.

[0176] Figure 11 depicts a composition of a MAC Protocol Data Unit (PDU) in accordance with an implementation of the method and programming system described with reference to Figure 10. The MAC Protocol Data Unit referred to in the procedure for buffer state report in accordance with the programming method described with respect to Figure 10 incorporates a control element for performing D2D-related signaling. Preferably, the programming information for D2D communication may be a dedicated D2D Buffer Status Report, which may be implemented by a MAC control element for D2D communication. Consequently, the MAC Protocol Data Unit transmitted in the PUSCH may include, in addition to MAC control elements, such as MAC BSR/PHR CEs (indicated in Figure 11 as MAC CE1 and MAC CE2), used to perform programming on network traffic. LTE uplink, also one or more D2D MAC control elements, which will be used to perform programming of resources for data transmission from the transmitting user equipment to the receiving user equipment on the direct link channel.

[0177] The D2D MAC control element in the MAC PDU may further be associated with an identification number. Said identification number may be, for example, an ID of the reserved logical channel, which may be stored in the MAC PDU header, i.e., MAC subheader. Advantageously, the identification number can be stored in the R/R/E/LCID subheader corresponding to the D2D MAC CE. Consequently, the eNodeB will be able to distinguish which buffer state report in the MAC PDU needs to be used for D2D data transmission scheduling procedures in the direct link connection or for LTE cellular uplink traffic scheduling.

[0178] This logical channel ID is in accordance with an embodiment of the invention, one of the reserved logical channel IDs (LCIDs) specified in TS36.321 Table 6.2.1-2, incorporated herein by reference.

[0179] The D2D communication method described with reference to Figure 10 may further include a new augmented logical channel prioritization procedure (LCP) for LTE uplink transmissions in PUSCH. An LCP procedure is commonly responsible for allocating data to be transmitted on different channels in a MAC PDU. Each D2D capable user equipment may include a multiplexing unit at the MAC layer (not shown) for multiplexing data from different logical channels and MAC control elements into said MAC PDU. The MAC control elements will carry, for example, programming-related information used to perform scheduling of LTE uplink traffic and direct D2D communication.

[0180] The LCP procedure defines a relative priority order according to which the user equipment can construct the MAC PDU. Advantageously, the LPC procedure for LTE uplink transmission can define the position or order of the data parts that make up the MAC PDU. Just as an explanatory example, the case could be considered, where 100 bytes are available to the MAC PDU and the data to be multiplexed into the MAC PDU consists of 200 bytes.

[0181] Based on the LCP procedure, the user equipment will be able to decide which of the 200 bytes can be transmitted within the MAC PDU and in which order. The remaining 100 bytes of data will then be transmitted in the predefined order in the next MAC PDU, based on the priorities defined in the LCP procedure. One skilled in the art will clearly understand that the above examples are for illustrative purposes only and the invention should not be limited to one embodiment, where 100 bytes are available for the MAC PDU. Conversely, according to the invention, more than 100 bytes or less than 100 bytes may be available for MAC PDU. The number of bytes available for the MAC PDU is a design option that will be defined on a case-by-case basis depending on the hardware characteristics of the devices, such as user equipment.

[0182] According to an advantageous arrangement, the MAC PDU transmitted in the PUSCH can be organized according to the following priorities, in descending order, defined in the LCP procedure: - MAC control element for C-RNTI or UL data -CCCH; - MAC control element for D2D BSR; - MAC control element for BSR, with the exception of BSR included for padding; - MAC control element for PHR or Extended PHR; - data from any Logical Channel, except UL-CCCH data; - MAC control element for BSR included for backfilling.

[0183] According to the priority order defined by the LCP procedure described above, the D2D buffer state report has a higher priority with respect to the buffer state report used to perform a scheduling procedure for cellular uplink traffic of LTE.

[0184] Clearly, the above order is simply an example for explanatory purposes. According to a further advantageous arrangement, more importance could be given to LTE traffic by assigning a higher priority to buffer status reporting corresponding to LTE uplink traffic. Consequently, the LCP procedure for D2D capable UE may set the following priorities in descending order: - MAC control element for C-RNTI or UL-CCCH data; - MAC control element for BSR, with the exception of BSR included for padding; - MAC control element for D2D BSR; - MAC control element for PHR or Extended PHR; - data from any Logical Channel, except UL-CCCH data; - MAC control element for BSR included for backfilling.

[0185] Again, the examples of LCP procedures reported above are just two of several possible options for defining relative priorities and need not be considered as limiting the invention. Other priority orders can be clearly defined according to network configuration and communication specifications.

[0186] Buffer Status Reports common in LTE systems can be 1 or 4 bytes long (short and long BSR respectively). Additionally, a truncated 2-byte BSR can also be used as described in the introductory portion, section “Buffer Status reporting / Scheduling Request procedure for uplink scheduling”.

[0187] In a D2D communication scenario, the communication configuration is not managed/configured by the eNodeB, but instead by a separate entity, for example, such as a D2D server in the core network or respectively a D2D Management entity in the EU. The D2D Management entity which could also be referred to as ProSe Management Entity (PME) resides in the UE and is supplied with configuration parameters, for example, protocol/bearer configuration, used during D2D communication. Provisioning is carried out by pre-configuration or, in the case of network coverage, by signaling between the PME and the D2D Function/server in the core network. To support D2D communication through “D2D Bearer”, the PME then configures Layer 2 and the physical layer based on the configuration parameters provided in advance. Since the eNodeB is not aware of the detailed configuration parameters for data transfer over the D2D direct link connection, such as D2D bearers, user equipment uses data transfer without controlling the quality of service (QoS) of the network point of view as guaranteed by LTE traffic is supplied for D2D data communication. Since detailed D2D bearer settings may not be known to eNB, the D2D Buffer Status Report can advantageously include only the amount of data that is in the buffer for all D2D bearers. This would be in contrast to a BSR for LTE traffic/bearers that is organized at the logical channel group level.

[0188] In addition to the information on the amount of D2D carrier data stored in the transmission buffer, the D2D BRS MAC CE may also advantageously include some additional information that allows more effective programming of D2D data communication per eNB. As an example, the D2D buffer status report may, in accordance with another embodiment of the invention, include an indication of the D2D traffic or bearer type to which D2D time/frequency resources are to be allocated per eNB. Advantageously, the D2D BSR MAC CE may include one or more flag types indicating the type of traffic or bearer. As an example, a flag type may include information whether the data to be transmitted on the D2D direct link channel is speech data, or another type of non-conversional data, such as video data.

[0189] Based on the flag type, which carries traffic bearer type information, the eNodeB can schedule resources more effectively. As an example, from the flag type, the eNodeB may result that the transmitted data is voice data, such as VOIP data. Consequently, the eNodeB can allocate resource priority in the usual way as done for voice data transmission on the LTE uplink data channel. Specifically, the eNodeB can allocate the resources to transmit a certain number of bits periodically. As an example, for a voice signal, which is a periodic signal, the eNodeB can allocate resources to transmit over the D2D direct link data channel resources every 20 ms.

[0190] In contrast to this, if the flag type indicates that the data to be transferred via the D2D direct link data channel is a non-conversational service, such as video data, the eNodeB may allocate, based on the Flag type information in the BSR, resources not periodically, but instead as an allocation of time.

[0191] In conclusion, for LTE communication, traffic is controlled by the network and therefore the eNodeB has information about, for example, which QoS different carriers need to support. However, the eNodeB cannot retrieve this information for D2D data traffic, since the latter occurs without network mediation. Consequently, with buffer state reporting, the user equipment has to provide this information to the eNodeB for D2D communications. For this purpose, the flag type information in the BSR can advantageously provide the eNodeB with information about the bearers and data traffic on the D2D direct link channel, which are otherwise not directly obtainable by the eNodeB. This information could then be used by the eNB in order to prioritize D2D resource allocation among multiple D2D transmission UEs. As an example when eNB receives multiple scheduling requests respectively from D2D related buffer state information, eNB needs to prioritize resource allocations. This could, for example, be done according to some additional alternative embodiment, based on the same priority information included in the D2D MAC CE buffer state. Priority information can be, for example, retrieved from the PME that configures Layer 2 and the physical layer based on configuration parameters provided in advance, as outlined above. As an example for each D2D bearer, the PME could associate a priority value similar to the logical channel priority for LTE bearers. When a D2D transmitting UE intends to transmit D2D data, it may, for example, include the priority value of the highest priority D2D bearer for which the UE requests resource transmission.

[0192] A user equipment is provided with transmission buffer memory for each logical channel data, used to temporarily store uplink data until it successfully transmits over the radio link to the eNodeB. Furthermore, the UE does not have uplink resources available to transmit the data or a buffer status report to the base station, thus making it necessary to transmit a scheduling request to the eNB, the process of which must be improved by first performing of the invention.

[0193] In the configuration explained in connection with Figure 10, the transmission user equipment sends a D2D-related buffer status report to the eNB when data from the D2D bearers to be transmitted over the direct link data channel D2D are temporarily stored in the transmission buffer of the transmission user equipment.

[0194] Additionally, the triggering of the D2D buffer state report may be immediately followed by the triggering of a scheduling request, as long as uplink shared channel (UL-SCH) resources are not available to transmit the buffer state report. Buffer triggered.

[0195] As explained before, scheduling requests can be transmitted through PUCCH resources allocated by the eNodeB or through the use of a RACH procedure. If not otherwise indicated, in the following, it will be assumed that such PUCCH resources, which are typically allocated periodically by the eNodeB, are available to the UE to transmit the scheduling request as soon as it is triggered; nevertheless, the invention is also applicable when using a RACH procedure instead. A scheduling request is typically one bit long, and the corresponding periodic PUCCH resources allow transmission of the scheduling request, but are not sufficient to transmit additional data such as the buffer state report or current transmission buffer data. Furthermore, based on the scheduling request, the eNB has no knowledge of whether the UE requests transmission resources for a direct link transmission (D2D data transmission) or for an LTE uplink transmission. Just based on the buffer state report as outlined above, the eNB can distinguish a request for D2D transmission and an LTE uplink transmission.

[0196] Figure 12 illustrates the transmission buffer in the user equipment and the messages exchanged with the base station to request resources to transmit data on the D2D direct link data channel. Furthermore, Figure 12 depicts the transmission of the buffer status report on the uplink data channel, and the scheduling request to the eNodeB, and data to the receiving user equipment via the direct link data channel. Figure 13 illustrates the process in the transmission user equipment to perform message and data exchange described in Figure 12.

[0197] According to the configuration illustrated in Figure 12, the triggering of the buffer status report/scheduling request for D2D data communication can rely on different conditions compared to the standard triggering. As an example, the D2D buffer state/scheduling request report could be triggered only when a certain amount of data has been stacked into the corresponding buffers. Deferring the buffer state/scheduling request report allows more data to reach the transmission buffer, and thus uplink transmissions carry more data in less time. Correspondingly, the triggering of the buffer status report/scheduling request is performed when sufficient data is in the transmission buffer, and not immediately when new data arrives in the empty transmission buffer. It is more effective to transmit large Transport Block sizes rather than transmitting smaller Transport Block sizes.

[0198] The configuration of figure 12 can be implemented in the following exemplary manner. Triggering a buffer status report on user equipment depends on two conditions, both of which must be met. Both trigger conditions in the context of an LTE implementation refer to the transmission of a buffer status report, which, however, directly leads to a transmission of a scheduling request, since it is assumed that no resources are available. to the user equipment to transmit the triggered buffer status report; thus, it can also be said that trigger conditions are defined for transmitting the scheduling request as well.

[0199] The first trigger condition requires new data to become available in the transmit buffer, which means that higher layer data must be transmitted over the direct link data channel to the receiving user equipment (UE2 ) and thus be inserted into the transmission buffer of the transmission user equipment (UE1). It should be noted that the first trigger condition is met regardless of whether the transmission buffer is empty or not, and regardless of the priority of the new data, as long as the new data becomes available in the transmission buffer.

[0200] This behavior is described in Figure 13, where the transmission user equipment (UE1) checks whether new data arrives in its transmission buffer.

[0201] The second trigger condition is basically responsible for postponing the triggering of the buffer/scheduling request state; it requires that there be sufficient data in the transmission buffer of UE1. Correspondingly, the data in the transmission buffer must generally exceed a predetermined threshold.

[0202] For the second trigger condition, the user equipment checks, for example, whether the amount of data in the transmission buffer changed by a predetermined value Δd compared to the amount of data stored in the transmission buffer at the time the Data Report Previous Buffer State was triggered/sent to the eNodeB.

[0203] In Figure 13, it is assumed that the transmission user equipment checks the second trigger condition that requires the amount of data to change a predetermined value. Although it seems logical to check the first and second trigger conditions in the order as illustrated in Figure 13, that is, first the first trigger condition and then the second trigger condition, this is not necessary. The user equipment may also first check the second trigger condition and then the first trigger condition.

[0204] It should also be noted that if the second trigger condition (requesting the amount of data to change a predefined value) is met, this automatically requires that the first trigger condition be met. In other words, the amount of data in the transmission buffer can then only suddenly change a predetermined amount of data if new data arrives in the transmission buffer, which corresponds to the request of the first trigger condition. Thus, in an alternative, the first trigger condition does not necessarily need to be verified; simply checks only the second trigger condition so that BSR/SR is triggered when the amount of data in the transmission buffer exceeds a certain threshold.

[0205] In the above example, the BSR transmission is triggered by changing the amount of data in the transmission buffer by a predetermined amount with respect to the amount of data in the transmission buffer at the time of the previous BSR trigger/transmission. However, other drive schemes can be used instead of the one described above. Alternatively, BSR transmission may be triggered if the amount of data in the transmission buffer of the transmission user equipment exceeds a predefined threshold.

[0206] An additional aspect of the invention relates to the rules for including/multiplexing a D2D 30 BSR in a MAC PDU transmitted on the PUSCH. According to the current LTE specifications (Rel-8/9/10/11), the UE is only allowed to include at most one BSR MAC CE in one MAC PDU. However, according to an embodiment of the invention, a D2D capable UE is permitted to multiplex a D2D BSR MAC CE and an LTE BSR MAC CE into a MAC PDU that is transmitted in PUSCH to the eNB. This ensures that the regular LTE uplink scheduling procedure is not delayed or impacted due to the D2D scheduling procedure.

[0207] In an implementation of the system and method described above, the restriction of including at most one BSR MAC in a MAC PDU may be maintained. This alternative implementation would use a MAC PDU structure that is similar to that known for standard LTE systems, with the difference that the MAC PDU may include a D2D BSR MAC CE instead of an LTE BRS MAC CE. Such a configuration would result in a delay in LTE BSR MAC CE or D2D BSR MAC CE transmission. Additionally, since only one of the LTE BSR MAC CE and the D2D BSR MAC CE will be included in the MAC PDU, new prioritization rules would need to be defined.

[0208] Yet another aspect of the invention relates to the procedure for canceling a buffer status report. In accordance with the regular buffer state reporting procedure specified in TS36.321 version 11.2.0, section 5.4.5, which is incorporated herein by reference, all triggered BSRs may be canceled when a BSR is added to a MAC PDU for transmission. According to a further embodiment of the invention, a D2D capable UE may not cancel a regular “LTE buffer status report” when a D2D buffer status report is included in a MAC PDU for transmissions. This solution ensures that the regular LTE uplink scheduling procedure/buffer status report is not impacted by the introduction of a D2D buffer status report.

[0209] Similarly and yet in accordance with another aspect of the invention, the Schedule Request (SR) prohibited timer may not be started when the Schedule Request has been triggered solely due to the fact that a D2D Buffer Status Report has been triggered. A D2D capable UE may, according to a further embodiment of the invention, not start the SR prohibited timer when SR was transmitted on the PUCCH for the case that the SR was only sent in order to request transmission of resources for a D2D communication. Similar to the embodiments outlined above, a D2D BSR may not delay the transmission of LTE data, i.e., in particular, high priority LTE data such as RRC signaling.

[0210] Another aspect of the invention relates to selecting the resource allocation mode for D2D data communication. As described above, there are two modes in which the UE can operate for resource selection for D2D data communication, that is, programmed operation mode (template) and autonomous operation mode (mode 2). The general principle should be, according to one embodiment, that the eNB controls the resource allocation mode a D2D capable UE operates. According to an advantageous implementation, a D2D capable UE, which has to transmit data from a D2D header, can always first operate in mode 1, i.e. establishing an RRC connection to the eNB (for the case of a UE RRCJDLE ) and sending buffer status report/scheduling request to the eNB as outlined in previous realizations.

[0211] If the UE does not receive any resource allocation for D2D transmission from the eNB, for example, within a predefined time window, or alternatively an explicit signaling indication from the eNB that indicates that the UE autonomously selects D2D time/frequency resource of a resource set for D2D data transmission, the UE will revert to mode 2 operation. Alternatively, the eNB could signal, for example, through system information propagation (SIB), that scheduled mode operation is not supported inside that cell. A flag can be, for example, advertising that indicates the availability of mode 1 within that cell. Based on this flag, a D2D capable transmitting UE will first attempt the model operation type (when the flag indicates that the model is operated in the cell) or immediately use mode 2 for resource allocation for D2D transmissions. Yet another solution could be that some special access classes could be introduced which are reserved for D2D purposes and based on those access classes, the eNB could control which D2D UEs are allowed to request resources for transmitting D2D data directly to the eNB, i.e. that is, they use mode 1 operation type. Basically, in each D2D UE an access class would be applied and some eNB signaling will indicate which classes are allowed to use mode 1 for resource allocation.

[0212] Yet a further aspect of the invention relates to the LCP procedure in the UE capable of supporting device-to-device communication. The user equipment can have both LTE channels or carriers to transmit data through the uplink data channel and D2D carriers. In such a scenario, data from D2D carriers can only be transmitted in D2D subframes or, in other words, in resources configured for D2D transmission over the direct link data channel. Similarly, data from LTE carriers can only be transmitted in dedicated LTE subframes, respectively time/frequency resources. Additionally, a logical channel prioritization procedure can be implemented, which takes into account the UE's ability to transmit over the LPE uplink channel and over the forward link channel.

[0213] In an advantageous implementation, a common LCP procedure can be developed for both LTE and D2D carriers. Consequently, in LTE subframes, data from D2D carriers will not be considered for the LCP procedure. In other words, D2D carriers can be considered suspended for the LCP procedure in LTE subframes, respectively time/frequency resources. Similarly, LTE carriers can be suspended for LCP operation in D2D subframes. Having a common LCP procedure for D2D and LTE communication allows you to reduce the complexity of D2D and LTE bearer management.

[0214] Alternatively, there may be two separate LCP procedures: one for D2D data transfer over the direct link channel, and one for LTE data traffic. Consequently, a dedicated LCP procedure for D2D carriers can be invoked for D2D subframes while the LCP defined for LTE is invoked on those subframes that are reserved for LTE-only transmissions. Since there is no QoS support for D2D bearers, and therefore the Prioritized Bit Rate (PBR) does not need to be defined, the D2D LCP procedure in this scheme may not need the use of the token bucket model. The scheme in which two separate LCP procedures for D2D and LTE are given may have the advantage that the D2D LCP procedure may be easier to configure.

[0215] Still, a further aspect of the invention relates to the timing of uplink transmission of discovery signals. In general, the transmission timing in D2D data transmission will be different than the transmission timing in LTE uplink data transmission. This is due to the fact that in LTE, the timing of a user's equipment is always controlled by the network, that is, by the eNodeB. Specifically, the network controls that all uplink signals from all user equipment under control of the eNodeB are received at the same time, in order to avoid interference. In a system capable of device-to-device communication the transmitting user equipment that transmits data to a receiving user equipment over the direct link data channel has to negotiate some synchronism with the receiving user equipment (or group of equipment). reception user number). The timing negotiated by the transmitting and receiving user equipment may be different than the timing controlled by the network for LTE uplink data traffic. According to a first solution, the D2D transmission user equipment RRC_Conectado transmits a discovery signal based on downlink reference timing also for D2D communication. In LTE systems, uplink timing is defined as the downlink reference timing plus an offset as a correction for the downlink timing. The offset is called timing alignment factor (TA) and its value is controlled by the eNodeB. According to the first solution, the correction value for the uplink will therefore be zero (T2=0) for D2D in FDD. In D2D transmission user equipment, TDD RRC_connected and RRCjdle can transmit discovery signal based on an offset of 624Ts. As a result, the downlink timing will be T2 = 624Ts.

[0216] Since two different timings for LTE and D2D discovery/communication are given, equipment in the RRC_Connected state may have two separate independent timing alignment capabilities residing at the MAC layer, which includes timing alignment values and/or or Sync alignment timers: that is, one for D2D and one for LTE.

[0217] Advantageously, the uplink timing functionality for D2D can be enabled only for D2D subframes. In other words, there will be an uplink timing jump between an LTE uplink subframe and D2D transmission. Additionally, NTA_Ref_D2D for D2D discovery can be set to zero.

[0218] According to a further advantageous aspect, which can be used alongside or alternatively to the previously described aspects, a stand-alone uplink timing adjustment (DL reference timing tracking) can be applied for D2D transmission during D2D subframes.

[0219] Finally, for D2D communication, user equipment will not receive Timing Advance (TA) commands from the eNodeB. Accordingly, according to a further advantageous aspect, which can be used together with or alternatively to the previously described aspects, a Sync Advance timer for D2D can be given. As an example, a TA timer can be set to infinity for D2D communications and started before the first D2D discovery or transmission occurs.

[0220] Another aspect of the invention is related to the discovery procedure for proximity services respectively Device to Device communication. Outside of coverage, there is no network available and therefore a dedicated or common resource allocation on the network side is not possible for transmit/receive resources. A further embodiment of the present invention addresses the above problem. Consequently, a D2D capable UE that is not in coverage of a network, i.e. also referred to as out of coverage, can transmit a fixed sequence on a fixed frequency that is repeated periodically with a fixed period. The procedure described above can be implemented by transmitting D2D Primary Synchronization Signals without device identity or with ProSe UE Identities, at a fixed frequency regardless of its actual operating frequency. Such implementation allows to perform detection by other D2D UEs in a very simple way.

[0221] For D2D capable UEs that are in coverage of a network, i.e., referred to as in-coverage UEs, the discovery procedure can be distinguished between idle mode UEs and connected mode UEs, i.e., UEs having established a RRC connection to the network. The two modes will be described below.

EU Idle

[0222] According to the first coverage discovery procedure, both Type 1 and Type 2 resources in the current cell for receiving D2D discovery messages (Rx Set) can be propagated in the System Information. Furthermore, the current cell may also propagate the Tx Set of a neighboring cell (and possibly also outside the Tx Set coverage) that could be at the same or different frequency. Reception of the discovery message is thus given by:

[0223] Rx Set = Tx Set of current cell + Tx Set of neighboring cell(s) + Tx Set Out of Coverage

[0224] Alternatively, in some deployments, the Tx Set of neighboring cell(s) and/or Out of Coverage TX Set may not be propagated by the current cell, as this may be an operator choice to record the propagation and/or since the neighboring cell may belong to a different PLMN, etc.. In such a case, the current cell can at least indicate that the Rx Set propagated in the current cell may not contain all the Tx Sets Interest pools outside this cell. In the simplest form, this could be indication of 1 bit (indicated as noted in the diagram below) in the D2D System information block.

[0225] Furthermore, a receiving UE needs to determine whether there would be other D2D devices outside this cell, whose discovery message(s) may also be of interest to said receiving UE. Consequently, said information can be transmitted by a higher layer, for example, a NAS application (based on, for example, Prose server). Upon such determination that some D2D/discovery of interest devices are unavailable in that cell, the UE will be able to find the possible neighboring cell(s) where such D2D/discovery of interest devices may be located. gift.

[0226] The method for deceiving D2D discovery signals as described above is shown in Figure 14.

[0227] According to a D2D capable communication system implementation, neighboring cells that support D2D discovery (i.e., have allocated certain resources for Type 1 and/or Type 2 resources) may be on a different frequency. In such a case, an indication of both PCI and frequency of neighboring cells can advantageously be made in propagating system information from the current cell.

[0228] Figure 15 schematically illustrates a situation in which a D2D capable UE performs discovery on neighboring cells. Discovery transmissions are limited by the maximum Tx power of the transmitting UE, and therefore discovery transmissions in distant cells will not be received by the D2D device.

[0229] Therefore, according to a further implementation, a D2D device expecting to receive discovery messages from neighboring cell(s) may not need to search/acquire all possible neighboring cells, but only those nearby from him. As an example, as shown in the diagram below, the D2D device does not attempt to detect/acquire D2D resources from neighboring cell 2 since any possible transmission from a D2D device in neighboring cell 2 is too far away/unreachable. Advantageously, a UE may attempt to detect/acquire D2D resources of neighboring cell x only if certain conditions are met. Advantageously, the UE may decide to detect or acquire D2D resources from a neighboring cell x (cell x) if:

[0230] Current_Cell_Quality - Cell_x_Quality < Threshold 1; or

[0231] Cell_x_Quality >= Current_Cell_Quality Connected Mode

[0232] Rx Set information may be signaled to a UE in connected mode by dedicated signaling (e.g., RRC information). The Rx set may include information about Tx Set of neighboring cell(s) or Tx Set Out of Coverage. Alternatively, the UE may acquire information as described in connection with the Idle Mode discussed above.

[0233] Additionally, a connected mode UE may also acquire Gap patterns to acquire (a) detection of interfrequency neighboring cell(s) and their D2D SI; and (b) the discovery message(s) on the interfrequency resources.

[0234] Accordingly, such UE may query the Gap pattern from the serving eNB possibly including information about possible gaps (gap length, repetition length, offset, etc.). Alternatively, such a UE can use autonomous gaps.

[0235] As the previous embodiment was mainly focused on the reception operation of D2D discovery in the following, the operation and transmission for D2D discovery is described in accordance with an exemplary embodiment of the invention.

[0236] A D2D capable UE may need to decide between which type of resource to use to transmit the D2D discovery signals/messages. Based on this decision, it may need to consequently request resources in the eNB (e.g. for Type 2B resources) and may therefore need to establish an RRC connection for this purpose (if the UE was in Idle Mode).

[0237] According to an advantageous implementation, the decision of the type of resources that should be used to transmit D2D discovery signals or messages can be based on the following criteria: 1) Discovery Type, i.e., based on the transmission of Application triggering discovery - Mapping between Discovery and Application resource type could be specified, pre-configured, indicated by the Discovery Server (Pro-se), etc.; 2) The last successful Discovery Transmission (for example, for the same discovery application); 3) Idle Mode Mobility State.

[0238] Advantageously in an implementation, slow or stationary UEs can always ask for a particular resource type (e.g., Type 2B); Mobile UEs (e.g. Medium mobility) will use, for example, Type 1. The request types mentioned above will be explained in the following sections.

Request for Type 2B Resources

[0239] If the UE decides to use Type 2B resources, it must request that eNB be granted those Type 2B resources. This can be accomplished by the following procedures: • Using Special RACH resources (e.g. Preamble, RACH transmission resources); • A new cause value(s) in msg3 (RRC Connection Request) - to request Type 2B D2D Tx resources • Since the UE does not intend to establish an LTE bearer (e.g., a termination on the LTE CN), a Lightweight RRC protocol can be used for this purpose, e.g. no security context needs to be established, no configuration/measurement reporting, etc.; • NAS Signaling - UE NAS informs MME, MME checks and indicates/requests that eNb use Type 2B; eNB grant Type 2B resources to this UE (in RRC Reconfiguration). Application to Resource mapping is fixed and therefore Pro-server/application/CN decide the type of resource to be used, for example Durane Authentication of D2D services.

[0240] Additionally, the UE may indicate the estimated length of use of the Type 2B resource while requesting for such resource. If the request is not honored (e.g., UE receives a 2B resource reject/RRC connection release message, or no response within certain time), the UE starts using Type 1. Mobility (Handover, Reestablishment)

[0241] Mobility will not guarantee that previously allocated D2D resources are still available for use. So, there is the following treatment for D2D resources allocated during mobility: • Maintained as is - Negotiated in X2; for example, Neighbors reserve the same physical resources for D2D discovery transmission • Reconfigured by the target in HO Command/reestablishment message + reconfiguration message; • Deconfigured/released as a result of receiving HO Command;

[0242] UE asks for the same after Delivery to target cell (target eNB can allocate same cell as previous or new resources)

[0243] Resource Discovery Type 2B

Signaling

[0244] According to an advantageous implementation, dedicated resources (type 2B) can be released by the UE, when the same is no longer requested (i.e., the UE would not transmit D2D discovery). Alternatively, the eNB can request the resources back (e.g., to avoid congestion in LTE cellular communication). Such release can be done as described below: • Implicit Release • Upon expiry of timer (configured/specified) • If the UE wishes to retain the same (Type 2B resources) additionally, it needs to send a “keepalive” signaling to eNB. • Upon mobility (handover, reestablishment): the UE simply relinquishes the Type 2B resource used in the source cell. - Upon RRC Connection Release (already decided in RAN2#85): the UE simply relinquishes the Type 2B resource used in the source cell • Explicit Release - New Signaling (RRC, MAC CE etc.) • from the UE (initiating 2B release) when you no longer need it; • the network (starting 2B release) in case of LTE network congestion (overlap).

[0245] Upon network initiation of releasing Type 2B resources, the UE may begin using Type 1 resources if it still needs to transmit discovery messages/signals.

[0246] D2D-related System Information Propagation (SIB)

[0247] A D2D SIB is a propagation that pertains to D2D discovery in the underlying network. This information may not be used/useful for UEs only interested in the underlying network (LTE). The network can propagate D2D-related information (called SIB D2D(s)) into separate System Information Blocks (SIB). The same or different SIBs can indicate the D2D resources to receive Intercell Discovery messages.

[0248] Receive Resources in Current Cell = Transmit Resources in Current Cell + Transmit Resources from Neighboring Cell

[0249] SIB D2Ds change

[0250] A new paging message could be used (New D2D P-RNTI) that carries information about the D2D SIB modification. Alternatively, the Timer-based mechanism (not changing more often than 'x' ms.) can be sweated so that the D2D device of interest must reacquire the D2D SIB (only) on timer expiration. As another alternative, a modification of SIB D2D could impact the value tag on SIB1 like today or it could even have its own value tag.

HARDWARE AND SOFTWARE IMPLEMENTATION OF THE INVENTION

[0251] Another aspect of the invention relates to the implementation of the various embodiments and aspects described above using hardware and software. In this connection, the invention provides a user equipment (mobile terminal) and an eNodeB (base station). User equipment is adapted to perform the methods described herein. Furthermore, the eNodeB comprises means that allow the eNodeB to evaluate the IPMI pool quality of respective user equipments from the IPMI pool quality information received from the user equipments and to consider the IPMI pool quality of different user equipments. users in programming the different user equipment by a programmer.

[0252] It is further recognized that the various embodiments of the invention can be implemented or realized using computing devices (processors). A computing device or processor may, for example, be general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, etc. The various embodiments of the invention may also be realized or embodied by a combination of these devices.

[0253] Furthermore, the various embodiments of the invention can also be implemented through software modules, which are executed by a processor or directly in hardware. Also, a combination of software modules and a hardware implementation may be possible. Software modules can be stored on a type of computer-readable storage media, for example, RAM, EPROM, EEPROM, flash memory, registers, hard drives, CD-ROM, DVD, etc.

[0254] It should also be noted that the individual characteristics of the different embodiments of the invention may, individually or in arbitrary combination, be the subject of another invention.

[0255] It would be appreciated by one skilled in the art that numerous variations and/or modifications can be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments should therefore be considered in all illustrative and non-restrictive relationships.

Claims (30)

1. COMMUNICATION EQUIPMENT FOR DEVICE-TO-DEVICE (D2D) COMMUNICATION, communication equipment characterized by comprising: a transmitter, which, in operation, transmits to the base station a Scheduling Request (SR) to request Uplink Shared Channel resources (UL-SCH) if a Buffer Status Report (BSR) direct link is triggered and an uplink lease is not configured and, in operation, transmits to the base station, the direct link BSR on the UL-SCH resources programmed by the uplink grant, wherein the direct link BSR is a message to provide the base station with information about a quantity of D2D data for transmission to a user destination equipment; and a receiver, which, in operation, receives from the base station, the uplink grant to schedule the UL-SCH resources in response to the transmitted SR, and, in operation, receives a D2D grant that schedules D2D resources to the D2D data in response to the forward link BSR, wherein a transmitter, in operation, transmits D2D data to the user's destination equipment on the D2D resources scheduled by the D2D grant, and where the uplink BSR has a higher priority in resource scheduling than the Direct link BSR, the uplink BSR being a message to inform the base station of an amount of uplink data to be transmitted to the base station. 2. EQUIPMENT, according to claim 1, characterized by the transmitter transmitting the direct link BSR in a direct link BSR MAC control element, with an index identifying a type of the D2D data and/or with a MAC header that includes a logical channel ID. 3. EQUIPMENT, according to claim 1, characterized in that the D2D resources are a set of subframes for D2D communication. 4. EQUIPMENT, according to claim 1, characterized by the transmitter transmitting the SR to the base station on a Physical Uplink Control Channel (PUCCH) or a Physical Random Access Channel (PRACH). 5. EQUIPMENT according to claim 1, characterized in that the direct link BSR is a first type of direct link BSR or a second type of direct link BSR that is smaller in data length than the first type of link BSR direct. 6. EQUIPMENT according to claim 1, characterized in that the transmitter transmits a MAC Protocol Data Unit (PDU) that includes at most one direct link BSR MAC control element, including the direct link BSR and an element BSR MAC control module including an uplink BSR, wherein the uplink BSR is a message to provide the base station with information about an amount of uplink data for transmission to the base station. 7. EQUIPMENT, according to claim 1, characterized in that the D2D resources are different from the UL-SCH resources. 8. COMMUNICATION METHOD FOR DEVICE-TO-DEVICE COMMUNICATION (D2D), characterized by comprising: transmitting to the base station a Scheduling Request (SR) to request Uplink Shared Channel (UL-SCH) resources if a direct Link Report Buffer State (BSR) is triggered and an uplink lease is not configured; receiving from the base station an uplink grant to schedule the UL-SCH resources in response to the transmitted SR; transmit to the base station, the direct link BSR on the UL-SCH resources scheduled by the uplink grant, wherein the direct link BSR is a message to provide the base station with information about the amount of D2D data for transmission to a user destination; receiving a D2D grant that schedules D2D resources to the D2D data in response to the transmitted direct link BSR; and transmitting the D2D data to the user equipment on the D2D resources scheduled by the D2D grant, wherein the uplink BSR has a higher priority in resource scheduling than the direct link BSR, the uplink BSR being a message to inform the base station about an amount of uplink data to be transmitted to the base station. 9. METHOD according to claim 8, characterized in that the direct link BSR is transmitted within a direct link BSR MAC control element that includes an index to identify a type of the D2D data and/or with a MAC header which includes a logical channel ID. 10. METHOD, according to claim 8, characterized in that the D2D resources are a set of subframes for D2D communication. 11. METHOD, according to claim 8, characterized in that it comprises transmitting the SR to the base station on a Physical Uplink Control Channel (PUCCH) or on a Physical Random Access Channel (PRACH). 12. METHOD according to claim 8, characterized in that the direct link BSR is a first type of direct link BSR or a second type of direct link BSR that is shorter in length than the first type of direct link BSR . 13. METHOD, according to claim 8, characterized by transmitting a MAC Protocol Data Unit (PDU) that includes at most one direct link BSR MAC control element, including the direct link BSR and a BSR MAC control element, including an uplink BSR, wherein the uplink BSR is a message to provide the base station with information about an amount of uplink data for transmission to the base station. 14. METHOD, according to claim 8, characterized in that D2D resources are different from UL-SCH resources. 15. COMMUNICATION EQUIPMENT, characterized by comprising: a receiver, which, in operation, receives from a user equipment a Programming Request (SR) to request Uplink Shared Channel (UL-SCH) resources and a direct Report link Buffer Status (BSR) is triggered and an uplink lease is not configured and, in operation, receives from user equipment the forward link BSR on the UL-SCH resources programmed by the uplink lease, where the forward link BSR is a message for providing communication equipment with information about a quantity of device-to-device (D2D) data for transmission from a user equipment to a user destination equipment; a transmitter, which, in operation, transmits to the user equipment an uplink grant to schedule UL-SCH resources in response to the received SR and, in operation, transmits D2D grant to determine D2D resources for D2D communication in response to the BSR of direct link received; and wherein the uplink BSR has a higher priority in resource scheduling than the direct link BSR, wherein the uplink BSR is a message that informs the base station of an amount of uplink data for transmission to the base station. 16. EQUIPMENT according to claim 15, characterized in that the direct link BSR is received within a direct link BSR MAC control element, which includes an index to identify a type of the D2D data and/or with a header MAC that includes a logical channel ID. 17. EQUIPMENT, according to claim 15, characterized in that the D2D resources are a set of subframes for D2D communication. 18. EQUIPMENT, according to claim 15, characterized in that the SR is transmitted from the user equipment to the communication equipment on a Physical Uplink Control Channel (PUCCH) or on a Physical Random Access Channel (PRACH). 19. EQUIPMENT according to claim 15, characterized in that the direct link BSR is a first type of direct link BSR or a second type of direct link BSR that is smaller in data length than the first type of link BSR direct. 20. EQUIPMENT according to claim 15, characterized in that the receiver receives a MAC Protocol Data Unit (PDU) that includes at most one direct link BSR MAC control element for the direct link BSR and a of MAC control from BSR to uplink BSR, wherein the uplink BSR is a message to provide the communication equipment with information about an amount of uplink data for transmission to the communication equipment. 21. EQUIPMENT, according to claim 15, characterized in that the D2D resources are different from the UL-SCH resources. 22. COMMUNICATION METHOD, characterized by: receiving from the user equipment a Scheduling Request (SR) to request Uplink Shared Channel (UL-SCH) resources if a Buffer State Report (BSR) direct link is triggered and an uplink lease is not configured; transmitting to the user equipment an uplink grant to schedule UL-SCH resources in response to the transmitted SR; receive from the user equipment, the direct link BSR on the UL-SCH resources programmed by the uplink grant, wherein the direct link BSR is a message to provide the communications equipment with information about the amount of device-to-device (D2D) data ) for transmission from the user equipment to a destination user equipment; and transmitting D2D grant that schedules D2D resources to the D2D data in response to the received direct link BSR; wherein the uplink BSR has a higher priority in resource scheduling than the direct link BSR, wherein the uplink BSR is a message to inform the base station of an amount of uplink data for transmission to the base station. 23. METHOD according to claim 22, characterized in that the direct link BSR is received within a direct link BSR MAC control element that includes an index to identify a type of the D2D data and/or with a MAC header which includes a logical channel ID. 24. METHOD, according to claim 23, characterized in that the D2D resources are a set of subframes for D2D communication. 25. METHOD, according to claim 23, characterized in that the SR is transmitted from the user equipment to the communication equipment on a Physical Uplink Control Channel (PUCCH) or on a Physical Random Access Channel (PRACH). 26. METHOD according to claim 23, characterized in that the direct link BSR is a first type of direct link BSR or a second type of direct link BSR that is smaller in data length than the first type of direct link BSR. direct link. 27. METHOD, according to claim 23, characterized by receiving a MAC Protocol Data Unit (PDU) that includes at most one direct link BSR MAC control element for the direct link BSR and a direct link BSR MAC control element of MAC control from BSR to uplink BSR, wherein the uplink BSR is a message to provide the communication equipment with information about an amount of uplink data for transmission to the communication equipment. 28. METHOD, according to claim 23, characterized in that D2D resources are different from UL-SCH resources. 29. INTEGRATED CIRCUIT, characterized by: circuit, which, in operation, controls: transmitting to the base station a Scheduling Request (SR) to request Uplink Shared Channel (UL-SCH) resources and a Buffer Status Report ( BSR) is triggered and an uplink lease is not configured; receiving from the base station an uplink grant to schedule the UL-SCH resources in response to the transmitted SR; transmit to the base station the direct link BSR on the UL-SCH resources scheduled by the uplink grant, wherein the direct link BSR is a message to provide the base station with information about a quantity of device-to-device (D2D) data for transmission to a user's target equipment; receiving D2D grant that schedules D2D resources to the D2D data in response to the transmitted direct link BSR; transmitting the D2D data to the user's target equipment on the D2D resources programmed by the D2D grant; at least one output coupled to the circuit, which, in operation, outputs data; wherein the uplink BSR has a higher priority in resource scheduling than the direct link BSR, wherein the uplink BSR is a message to inform the base station of an amount of uplink data for transmission to the base station. 30. INTEGRATED CIRCUIT, characterized by comprising: circuit, which, in operation, controls: receiving a Programming Request (SR) from a user equipment to request Uplink Shared Channel (UL-SCH) resources and a Status Report of Direct link buffer (BSR) is triggered and an uplink lease is not configured; transmitting to the user equipment an uplink grant to schedule the UL-SCH resources in response to the received SR; receive from the user equipment the direct link BSR on the UL-SCH resources scheduled by the uplink grant, wherein the direct link BSR is a message to provide the communications equipment with information about a device-to-device (D2D) data quantity for transmission from the user's equipment to the user's destination equipment; and transmitting D2D grant that schedules D2D resources to the D2D data in response to the received direct link BSR; at least one output coupled to the circuit, which, in operation, outputs data; wherein the uplink BSR has a higher priority in resource scheduling than the direct link BSR, wherein the uplink BSR is a message to inform the base station of an amount of uplink data for transmission to the base station.