RU2779409C2 - Deterministic behavior of ue for csi/srs message during drx - Google Patents

Abstract

FIELD: communication.

SUBSTANCE: invention relates to a method for transmission of a periodic message of channel status information (hereinafter – CSI) and/or sounding reference symbol (hereinafter – SRS) from UE to eNodeB. According to one embodiment, UL provisions and/or DL assignments received only before and during a subframe N-4 are taken into account, while UL provisions and/or DL assignments received by UE after the subframe N-4 are rejected, when defining. In addition, timers related to DRX are taken into account in the subframe N-4, when defined. In the second embodiment, controlling elements MAC of eNodeB giving UE a command to enter DRX, i.e., to become inactive, are taken into account, when defining, only if they are received before the subframe N-4, i.e., before and during a subframe N-(4+k).

EFFECT: avoidance of double decoding in eNodeB in transition phases; invention defines deterministic behavior of UE, according to which eNodeB can unequivocally determine, whether UE will transmit CSI/SRS or not.

16 cl, 20 dwg

Description

The field of technology to which the invention belongs

The invention relates to methods for transmitting channel quality messages and/or sounding reference symbols from a mobile station to a base station. The invention also provides a mobile station and a base station for performing the methods described in this application.

Prior Art

Long Term Development (LTE)

Third generation (3G) mobile systems based on WCDMA radio access technology are being deployed on a large scale around the world. The first step in the improvement or development of this technology entails the introduction of High Speed Downlink Packet Access (HSDPA) and Enhanced Uplink, also referred to as High Speed Uplink Packet Access (HSUPA), giving a radio access technology that is very competitive.

In order to be prepared for further increasing user demands and to be competitive with relatively new radio access technologies, 3GPP has introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to meet the needs of carriers for high-speed data and multimedia transport, as well as high-bandwidth speech support for the next decade. The ability to provide high bit rates is a key measure for LTE.

The specification of a separate work (WI) in Long Term Evolution (LTE) called UMTS Terrestrial Radio Access Evolved (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN) has been finalized as Release 8 (LTE Rel.8). The LTE system introduces efficient packet-based radio access and radio access networks that provide full IP-based functionality with low latency and low cost. In LTE, scalable multiple transmission bands are specified as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz in order to perform flexible system deployment using a given spectrum. In the downlink, orthogonal frequency division multiplexing (OFDM) based radio access has been adopted due to its inherent robustness to multipath interference (MPI) due to low symbol rate, use of cyclic prefix (CP) and its relationship with different band arrangements. transmission frequencies. Radio access based on Single Carrier Frequency Division Multiple Access (SC-FDMA) has been adopted in the uplink because global coverage has been given priority over improving the maximum data rate, taking into account the limited transmit power of the user equipment (UE) . A variety of major packet radio access technologies are used, including multiple input multiple output (MIMO) channel transmission techniques, and a high performance control signaling structure is achieved in LTE Rel.8/9.

LTE architecture

The general architecture is shown in Fig. 1 and a more detailed representation of the E-UTRAN architecture is given in FIG. 2. E-UTRAN consists of an eNodeB providing E-UTRA User Plane (PDCP/RLC/MAC/PHY) and Control Plane (RRC) protocol terminations to a User Equipment (UE). The eNodeB (eNB) contains a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data control protocol (PDCP) layer, which include user plane header compression and encryption functionality. It also offers Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions, including radio resource administration, access control, scheduling, uplink negotiated quality of service (QoS) implementation, cell information broadcast, user plane and control plane data encryption/decryption, and downlink user plane packet header compression/decompression. /uplink. The eNodeBs are interconnected with each other via the X2 interface.

The eNodeBs are also connected via an S1 interface to an EPC (Evolved Packet Core), more specifically to an MME (Mobility Management Entity) via an S1-MME and to a Serving Gateway (SGW) via an S1-U. The S1 interface maintains a many-to-many relationship between the MME/Serving Gateways and the eNodeB. The SGW routes and transmits user data packets while acting as a mobility anchor point for the user plane during handoffs between eNodeBs and as an anchor point for mobility between LTE and other 3GPP technologies (terminating the S4 interface and passing traffic between 2G/ 3G and GW PDN). For user equipments in the idle state, the SGW terminates the downlink data route and initiates paging when the downlink data arrives for the user equipment. It administers and stores user equipment contexts, such as IP bearer service parameters, internal network routing information. It also performs duplication of user traffic in case of legitimate interception.

The MME is the master control node for the LTE access network. It is responsible for the tracking and paging procedure for idle user equipment, including retransmissions. It is involved in the bearer activation/deactivation process and is also responsible for selecting the SGW for the user equipment at initial connection and during intra-LTE handover, including core network node (CN) relocation. It is responsible for user authentication (through interaction with the HSS). The non-access stratum (NAS) signaling is terminated at the MME, and is also responsible for generating and assigning temporary identifiers to user equipments. It checks the authorization of the user equipment to reside in the public mobile network (PLMN) and imposes restrictions on the guest user equipments. The MME is a network endpoint for encryption/integrity protection for NAS signaling and deals with security key administration. Lawful signaling interception is also supported by the MME. The MME also provides a control plane function for mobility between LTE and 2G/3G access networks by terminating the S3 interface in the MME of the SGSN. The MME also terminates the S6a interface to the home HSS for guest user equipments.

Component carrier structure in LTE (version 8)

поднесущих, как также изображено на фиг. 4.The 3GPP LTE (Release 8) downlink component carrier is divided in the time-frequency domain into so-called subframes. In 3GPP LTE (Release 8), each subframe is divided into two downlink slots, as shown in FIG. 3, where the first downlink slot contains a control channel region (PDCCH region) in the first OFDM symbols. Each subframe consists of a predetermined number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), where each symbol is spread over the entire component carrier bandwidth. Thus, each of the OFDM symbols consists of a number of modulation symbols transmitted on the respective

subcarriers, as also shown in FIG. four.

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

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

элементов ресурсов, соответствующих одному слоту во временной области и 180 kHz в частотной области (для дополнительных подробностей относительно сетки ресурсов нисходящей линии связи смотри, например, TS 36.211 3GPP, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8”, раздел 6.2, доступную в http:/www.3gpp.org и включенную в настоящее описание посредством ссылки.Assuming a multi-carrier communication system, such as using OFDM, such as used in 3GPP Long Term Evolution (LTE), the smallest resource unit that can be assigned by a scheduler is one "resource block". A physical resource block (PRB) is defined as

consecutive OFDM symbols in the time domain (eg, 7 OFDM symbols), and

consecutive subcarriers in the frequency domain, as exemplified in FIG. 4 (eg, 12 subcarriers for a component carrier). In 3GPP LTE (release 8), the physical resource block thus consists of

resource elements corresponding to one slot in the time domain and 180 kHz in the frequency domain (for more details on the downlink resource grid see e.g. 3GPP TS 36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation ( Release 8”, section 6.2, available at http:/www.3gpp.org and incorporated herein by reference.

последовательным поднесущим, охватывающим полный подкадр, называются «парой блоков ресурсов» или эквивалентно «парой RB», или «парой PRB».One subframe consists of two slots, such that there are 14 OFDM symbols per subframe when the so-called "regular" CP (cyclic prefix) is used, and 12 OFDM symbols per subframe when the so-called "extended" CP is used. For terminology in what follows, time-frequency resources equivalent to the same

consecutive subcarriers spanning a full subframe are called a "resource block pair" or equivalently a "RB pair" or a "PRB pair".

The term "component carrier" refers to a combination of multiple resource blocks in the frequency domain. In future versions of LTE, the term "component carrier" is no longer used, instead the terminology is changed to "cell", which refers to a combination of downlink and optionally uplink resources. The relationship between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information carried in the downlink resources.

Similar assumptions for component carrier structure also apply to later versions.

Carrier aggregation in LTE-A to support wider bandwidth

The frequency spectrum for advanced IMT was defined at the World Radiocommunication Conference 2007 (WRC-07). Although the entire frequency spectrum for enhanced IMT has been identified, the actual available frequency band varies according to each area or country. However, after the decision on the delineation of the available frequency spectrum, standardization of the radio interface began in the 3rd Generation Partnership Project (3GPP). 3GPP RAN TSG Meeting #39 adopted a subject matter description regarding "Further Advancement for E-UTRA (LTE-Advanced)". The subject matter covers the technology components considered for the development of E-UTRA, for example, to meet the requirements for advanced IMT.

The bandwidth that the LTE-Advanced system can support is 100 MHz, while the LTE system can only support 20 MHz. At present, radio spectrum scarcity has become a bottleneck in the development of wireless networks and, as a result, it is difficult to find a spectrum band that is wide enough for an evolved LTE system. As a result, there is a great need to find a way to obtain a wider bandwidth of the radio spectrum, with carrier aggregation functionality being a possible answer.

In carrier aggregation, two or more component carrier(s) are aggregated in order to support wider transmission bandwidths up to 100 MHz. Several cells in an LTE system are aggregated into one wider channel in an LTE-advanced system that is wide enough for 100 MHz, even if these cells in LTE are in different frequency bands.

All component carriers may be configured to be LTE Rel.8/9 compliant at least when the aggregate numbers of component carriers in the uplink and downlink are the same. Not all component carriers aggregated by user equipment may necessarily be Rel 8/9 compliant. An existing mechanism (eg, blocking) may be used to prevent Rel 8/9 user equipments from being placed on the component carrier.

A user equipment may simultaneously receive or transmit one or multiple component carriers (corresponding to a plurality of serving cells) depending on its functionality. Rel.10 LTE-A user equipment with receive and/or transmit functionality for carrier aggregation can simultaneously receive and/or transmit on multiple serving cells, while Rel.8/9 LTE user equipment can only receive or transmit on one serving cell, provided that the structure of the component carrier follows the specifications of Rel. 8/9.

Carrier aggregation is supported for both contiguous and non-continuous component carriers, with each component carrier limited to a maximum of 110 frequency domain resource blocks using 3GPP LTE (Release 8/9) numerical data.

3GPP LTE-A (Release 10) compliant user equipment can be configured to aggregate a different number of component carriers originating from the same eNodeB (base station) and possibly different frequency bands in 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.

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 originating from the same eNodeB need not provide the same coverage.

300 kHz может быть облегчен с помощью вставки небольшого числа неиспользуемых поднесущих между непрерывными составляющими несущими.The interval between the center frequencies of the continuously aggregated carrier components shall be a multiple of 300 kHz. This is to be compatible with the 100 kHz LTE (Rev. 8/9) 3GPP frequency raster and, at the same time, maintain subcarrier orthogonality at 15 kHz spacing. Depending on the aggregation scenario, the interval n

300 kHz can be facilitated by inserting a small number of unused subcarriers between the contiguous component carriers.

The essence of multi-carrier aggregation is only disclosed up to the MAC layer. For both uplink and downlink, there is one HARQ entity required in the MAC for each aggregation component carrier. There is (in the absence of uplink SU-MIMO) a maximum of one transport block per component carrier. The transport block and its possible HARQ retransmissions shall be mapped on the same component carrier.

The layer 2 structure with carrier aggregation enabled is shown in FIG. 5 and FIG. 6 for downlink and uplink, respectively.

When carrier aggregation is configured, the mobile terminal has only one RRC connection to the network. When establishing/re-creating an RRC connection, one cell provides secure ingress (one ECGI, one PCI and one ARFCN) and non-access layer mobility information (eg TAI) as in LTE Rel.8/9. After the establishment/re-establishment of the RRC connection, the component carrier corresponding to this cell is referred to as the downlink primary cell (Pcell). There is always one and only one downlink Pcell (PCell DL) and one uplink Pcell (PCell UL) configured to the user equipment in the connected state. In the configured component carrier set, the other cells are referred to as secondary cells (SCells), with the Scells being secondary component carriers downlink (SCC DL) and secondary component carriers uplink (SCC UL). The downlink and uplink Pcell characteristics are:

- for each SCell, the use of uplink resources by the UE, in addition to the downlink resources, is configurable, therefore, the number of configured DL SCCs is always greater than or equal to the number of UL SCCs, and no SCell can be configured to use only uplink resources

- The uplink Pcell is used to transmit layer 1 uplink control information

- Downlink Pcell cannot be deactivated unlike SCell

- from the perspective of the UE, each uplink resource belongs to only one serving cell

- the number of serving cells that can be configured depends on the UE capability

- re-creation is triggered when the downlink Pcell experiences Rayleigh fading (RLF), not when the downlink Csell experiences RLF

- Downlink Pcell may change with handover (i.e., with change of security key and RACH procedure)

- the lack of access layer information is taken from the downlink Pcell

- Pcell can only change with the handover procedure (i.e., with changing the security key and the RACH procedure)

- Pcell is used for PUCCH transmission.

The configuration and reconfiguration of component carriers can be performed using RRC. Activation and deactivation is performed using MAC controls. In intra-LTE handover, the RRC may also add, remove, or reconfigure the SCell for use in the target cell. When a new Scell is added, dedicated RRC signaling is used to transmit Scell system information, the information being mandatory for transmission/reception (same as in Rel-8/9 for handover).

When the user equipment is configured with carrier aggregation, there is one pair of uplink and downlink component carriers that is always active. The downlink component carrier of this pair might also be referred to as the 'DL anchor component carrier'. The same also applies for the uplink.

When carrier aggregation is configured, user equipment can be scheduled through multiple component carriers at the same time, but at most one random access procedure must be ongoing at any given time. Cross-carrier scheduling allows the PDCCH of a component carrier to schedule resources on another component carrier. For this purpose, the component carrier identification field is introduced in the respective DCI formats, called CIF.

The association between the uplink and downlink component carriers makes it possible to identify the uplink component carrier for which the grant applies when there is no cross-carrier scheduling. The relationship of downlink component carriers to uplink component carriers need not be one-to-one. In other words, more than one downlink component carrier may be associated with the same uplink component carrier. At the same time, a downlink component carrier can only communicate with one uplink component carrier.

RRC LTE states

LTE is based on only two main states: "RRC_IDLE" "RRC_CONNECTED".

In RRC_IDLE, the radio is inactive, but the ID is assigned and monitored by the network. More specifically, the mobile terminal in RRC_IDLE performs cell selection and reselection, in other words, it makes a decision as to which cell to locate. The cell selection (reselection) process takes into account the priority of each applicable frequency of each applicable radio access technology (RAT), the quality of the radio link, and the status of the cell (ie, whether the cell is blocked or reserved). The mobile terminal RRC_IDLE monitors the paging channel to detect incoming calls and also obtains system information. The system information mainly consists of parameters by which the network (E-UTRAN) can control the cell selection (reselection) process. The RRC specifies control signaling applicable to the mobile terminal in RRC_IDLE, namely paging information and system information. The mobile terminal behavior in RRC_IDLE is specified in TS 36.304, incorporated herein by reference.

In RRC_CONNECTED, the mobile terminal has an established RRC connection to the contexts in the eNodeB. The E-UTRAN assigns radio resources to the mobile terminal to facilitate transmission of (unicast) data over shared data channels. To support this operation, the mobile terminal monitors the associated control channels, which are used to indicate the dynamic assignment of shared transmission resources in time and frequency. The mobile terminal provides the network with messages about its buffer status and downlink channel quality, as well as neighbor cell measurement information, to enable the E-UTRAN to select the most suitable cell for the mobile terminal. These measurement messages include cells using other frequencies or RATs. The UE also receives system information mainly consisting of information required to use transmission channels. To increase its battery life, the UE in RRC_CONNECTED may be configured with a Discontinuous Receive (DRX) cycle. RRC is the protocol by which the E-UTRAN controls the behavior of the UE in RRC_CONNECTED.

Fig. 7 is a state diagram showing an overview of the respective functions performed by the mobile terminal in the IDLE and CONNECTED states.

Logical and transport channels

The MAC layer provides a data service for the RLC layer via logical channels. Logical channels are either control logical channels that carry control data such as RRC signaling or traffic logical channels that carry user plane data. Broadcast Control Channel (BCCH), Paging Control Channel (PCCH), Common Control Channel (CCCH), Multicast Control Channel (MCCH), and Dedicated Control Channel (DCCH) are control logical channels. Dedicated Traffic Channel (DTCH) and Multicast Traffic Channel (MTCH) are logical traffic channels.

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

Then multiplexing is performed between logical channels and transport channels in the downlink and uplink, respectively.

Level 1/Level 2 control signaling (L1/L2)

In order to inform scheduled users of their destination status, transport format, and other data related information (eg, HARQ information, transmit power control (NHC) commands), L1/L2 control signaling is transmitted on the downlink along with data. The L1/L2 control signaling is multiplexed with downlink data in a subframe, on the assumption that the user assignment may change from subframe to subframe. It should be noted that user assignment could be performed on a TTI (Transmission Time Interval) basis, where the duration of the TTI may be a multiple of subframes. The duration of the TTI may be fixed in the service area for all users, may be different for different users, or may even be dynamic for each user. Typically, L1/L2 control signaling only needs to be transmitted once per TTI. Without loss of generality, the following assumes that the TTI is equivalent to one subframe.

L1/L2 control signaling is transmitted on the Physical Downlink Control Channel (PDCCH). The PDCCH carries the message as downlink control information (DCI), which includes resource assignments and other control information for a mobile terminal or a group of UEs. Typically, multiple PDCCHs may be transmitted in one subframe.

Note that in 3GPP LTE, assignments for uplink data transmissions, also referred to as uplink scheduling grants or uplink resource assignments, are also transmitted on the PDCCH.

Considering scheduling grants, the information carried in L1/L2 control signaling can be divided into the following two categories, shared control information (SCI) carrying Cat 1 information and downlink control information (DCI) carrying Cat 2 information. /3.

Shared Control Information (SCI) Carrying Cat 1 Information

The shared control information part of the L1/L2 control signaling contains information related to the assignment (indication) of resources. Shared control information typically contains the following information:

- user ID indicating the user(s) to which the resources are assigned.

- RB assignment information for indicating resources (resource blocks (RB)) in which the user(s) is/are assigned. The number of resource blocks assigned may be dynamic.

- assignment duration (optional) if assignment across multiple subframes (or TTIs) is possible.

Depending on the setting of other channels and the setting of downlink control information (DCI) (see below), the shared control information may further comprise information such as ACK/NACK for uplink transmission, uplink scheduling information, DCI related information (resource, MCS, etc.).

Downlink Control Information (DCI) Carrying Cat 2/3 Information

The downlink control information part of the L1/L2 control signaling contains information related to the transmission format (Cat 2 information) of data transmitted to the scheduled user indicated by the Cat 1 information. transmission information Cat 2 carries information HARQ (Cat 2). The downlink control information needs to be decoded only by a user scheduled according to Cat 1. The downlink control information typically contains information regarding:

- Cat 2 information: modulation scheme, transport block size (payload) and coding rate, MIMO related information (multiple inputs and multiple outputs), etc. Either the transport unit (or payload size) or the code rate may be signaled. In any case, these parameters can be calculated from each other using modulation scheme information and resource information (number of assigned resource blocks).

- Cat 3 information: HARQ related information, eg hybrid HARQ process number, redundancy version, retransmission sequence number.

The downlink control information occurs in several formats that differ in overall size as well as in the information contained in its fields. The various DCI formats currently defined for LTE are detailed in 3GPP TS 36.212 "Multiplexing and channel coding", section 5.3.3.1 (available at http://www.3gpp.org, and incorporated herein by reference) .

Uplink Control Information (UCI)

Typically, uplink control signaling in mobile communication systems can be divided into two categories:

- data-associated control signaling is control signaling that is always transmitted along with uplink data and is used in the processing of this data. Examples include transport format indications, new data indicator (NDI), and MIMO parameters.

- non-data-associated control signaling is transmitted independently of any uplink data burst. Examples include HARQ acknowledgments (ACK/NACKs) for downlink data packets, channel quality indicators (CQIs) to support link adaptation, and MIMO feedback such as rank indicators (RIs) and precoding matrix indicators ( PMI) for downlink transmissions. Scheduling requests (SR) for uplink transmissions also fall under this category.

The control signaling associated with the uplink data is optional in LTE since the relevant information is already known to the eNodeB. Therefore, only non-data-associated control signaling exists in the LTE uplink.

As a result, a UCI may consist of:

- scheduling requests (SR)

- ACK/NACK HARQ in response to downlink data packets on the PDSCH (Physical Downlink Shared Channel). One ACK/NACK bit is transmitted in case of one codeword downlink transmission, while two ACK/NACK bits are used in case of two codeword downlink transmission.

- channel state information (CSI), which includes CQI, as well as MIMO-related feedback, consisting of RI and PMI. 20 bits per frame are used for CSI.

The number of UCIs that a UI can transmit in a subframe depends on the number of SC-FDMA symbols available for transmission of control signaling data. PUCCH supports eight different formats depending on the amount of signaled information. The following UCI formats in PUCCH are supported according to the following overview

Using different defined PUCCH formats (according to 5.4.1 and 5.4.2 of TS 36.211), the following combinations of UCIs in PUCCH are supported (see section 10.1.1 of TS 36.213):

- format 1a for 1 bit ACK HARQ or in case of FDD for 1 bit ACK HARQ with positive SR

- Format 1b for 1 bit ACK HARQ or 2 bit ACK HARQ with positive SR

- Format 1b for 4-bit ACK HARQ with channel selection when the UE is configured with more than one serving cell, in case of TDD when the UE is configured with one serving cell

- format 1 for positive SR

- format 2 for CSI message when not multiplexed with ACK HARQ

- Format 2a for CSI message multiplexed with 1 bit HARQ ACK for normal cyclic prefix

- Format 2b for CSI message multiplexed with 2 bit ACK HARQ for normal cyclic prefix

- format 2 for CSI message multiplexed with 1 bit HARQ ACK for extended cyclic prefix

- format 3 for up to 10 bit ACK HARQ for FDD and for up to 20 bit ACK HARQ for TDD

- format 3 for up to 11 bits corresponding to 10 bit ACK HARQ and 1 bit positive/negative SR for FDD and for up to 21 bits corresponding to 20 bit ACK HARQ and 1 bit positive/negative SR for FDD

- format 3 for multi-cell HARQ ACK, 1 bit positive/negative SR and CSI message for one serving cell.

Downlink and uplink data transmission

With regard to downlink data transmission, L1/L2 control signaling is transmitted on a separate physical channel (PDCCH) along with downlink packet data transmission. This L1/L2 control signaling typically contains information regarding:

- the physical resource(s) on which the data is transmitted (eg subcarriers or subcarrier blocks in the case of OFDM, codes in the case of CDMA). This information allows the mobile terminal (receiver) to identify the resources on which the data is being transmitted.

- When the 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 control signaling characteristic information is intended. This allows assignments transmitted on one component carrier that are intended for another component carrier ("cross-carrier scheduling"). This other cross-scheduled component carrier could be, for example, a non-PDCCH component carrier, ie, the cross-scheduled component carrier does not carry L1/L2 control signaling.

- The transport format that is used for transmission. This may be transport block size (payload size, information bit size), MCS (modulation and coding scheme) level, spectral efficiency, code rate, and so on. This information (usually together with the resource assignment (eg, the number of resource blocks assigned to the user equipment) allows the user equipment (receiver) to identify the size of the information bits, the modulation scheme, and the code rate in order to start demodulation, the rate mismatch process, and decoding. Modulation scheme can be signaled explicitly.

- Hybrid ARQ (HARQ) information:

-- HARQ process number: allows the user equipment to identify the hybrid ARQ process in which the data is displayed.

-- Sequence number or new data indicator (NDI): allows the user equipment to identify whether the transmission is a new packet or a retransmitted packet. If soft-combining is performed in the HARQ protocol, the sequence number or new data pointer, together with the HARQ process number, allows transmissions for the PDU to be soft-combined before decoding.

-- Redundancy and/or constellation version: tells the user equipment which hybrid ARQ redundancy version is being used (required for rate mismatch) and/or which modulation constellation version is being used (required for demodulation).

- UE ID (UE ID): tells which user equipment the L1/L2 control signaling is intended for. In exemplary implementations, this information is used to mask the L1/L2 control signaling CRC in order to prevent other user equipments from reading the information.

To enable transmission of uplink packet data, L1/L2 control signaling is transmitted on the downlink (PDCCH) to inform the user equipment of transmission details. This L1/L2 control signaling typically contains information regarding:

- the physical resource(s) on which the data is transmitted (eg subcarriers or subcarrier blocks in the case of OFDM, codes in the case of CDMA). This information allows the mobile terminal (receiver) to identify the resources on which the data is being transmitted.

- When the 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 control signaling characteristic information is intended. This allows assignments transmitted on one component carrier that are intended for another component carrier ("cross-carrier scheduling"). This other cross-scheduled component carrier could be, for example, a non-PDCCH component carrier, ie, the cross-scheduled component carrier does not carry L1/L2 control signaling.

- L1/L2 control signaling for uplink grants is transmitted on DL component carriers that are associated with an uplink component carrier or one of multiple DL component carriers if multiple DL component carriers carry communication with the same UL component carrier.

- The transport format that the user equipment should use for transmission. This may be transport block size (payload size, information bit size), MCS (modulation and coding scheme) level, spectral efficiency, code rate, and so on. This information (usually together with the resource assignment (e.g., the number of resource blocks assigned to the user equipment)) allows the user equipment (receiver) to identify the information bit size, modulation scheme and code rate in order to start demodulation, rate mismatch and decoding process. The modulation scheme can be signaled explicitly.

- Hybrid ARQ (HARQ) information:

-- HARQ process number: tells the user equipment from which hybrid ARQ process it should take data.

-- Sequence number or new data indicator (NDI): tells the user equipment to transmit a new packet or a retransmitted packet. If soft-combining is performed in the HARQ protocol, the sequence number or new data pointer, together with the HARQ process number, allows transmissions for a protocol data unit (PDU) to be soft-combined prior to decoding.

-- Redundancy and/or constellation version: tells the user equipment which hybrid ARQ redundancy version is in use (required for rate negotiation) and/or which modulation constellation version is in use (required for modulation).

- UE ID (UE ID): tells which user equipment the L1/L2 control signaling is intended for. In exemplary implementations, this information is used to mask the L1/L2 control signaling CRC in order to prevent other user equipments from reading the information.

There are several different possibilities on how to accurately transmit the pieces of information mentioned above in uplink and downlink data transmission. In addition, 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 required, i.e. not signaled in case of synchronous HARQ protocol.

- The redundancy and/or constellation version may not be required, and thus not signaled, if tracking merge is used (always the same redundancy and/or constellation version), or if the redundancy and/or constellation versions are predefined.

- Power control information can be further included in the control signaling.

- Control information associated with MIMO, such as, for example, precoding, may be further included in the control signaling.

- In the case of MIMO transmission with multiple codewords, the transport format and/or HARQ information for the multiple codewords may be included.

For uplink resource assignments (in the Physical Uplink Shared Channel (PUSCH)) signaled on the PDCCH in LTE, the L1/L2 control information does not contain the HARQ process number because the synchronous HARQ protocol is used for the LTE uplink. The HARQ process used for uplink transmission is specified by timing. In addition, it should be noted that the redundancy version (RV) information is jointly encoded with the transport format information, i.e., the RV information is inserted into the transport format (TF) field. The Transport Format (TF), respectively the Modulation and Coding Scheme (MCS) fields have, for example, a size of 5 bits, which corresponds to 32 entries. 3 entries in the TF/MCS table are reserved to indicate Redundancy Versions (RV) 1, 2 or 3. The remaining entries in the MSC table are used to signal the MCS level (TBS) explicitly indicating RV0. The PDCCH CRC field size is 16 bits.

For downlink assignments (PDSCH) signaled on the PDCCH in LTE, the redundancy version (RV) is signaled separately in a two bit field. In addition, the modulation sequence information is jointly encoded with the transport format and information. Similar to the uplink case, there is a 5 bit MCS field signaled on the PDCCH. 3 of the entries are reserved to signal an explicit modulation sequence, in the absence of transport format (transport block) information. For the remaining 29 entries, the modulation sequence and transport block size information are signaled. Channel quality message. The principle of link adaptation is fundamental to design a radio interface that is efficient for packet switched data traffic. Unlike early versions of UMTS (Universal Mobile Telecommunications System), which used closed loop power control to support circuit-switched services at an approximately constant data rate, link adaptation in LTE regulates the data rate (modulation scheme and channel coding rate). ) dynamically to match the prevailing radio bandwidth for each user.

For downlink data transmissions in LTE, the eNodeB typically selects a modulation scheme and a coding rate (MCS) depending on the prediction of downlink channel conditions. An important input to this selection process is the channel state information (CSI) feedback sent by the user equipment (UE) on the uplink to the eNodeB.

The channel state information is used in a multi-user communication system such as 3GPP LTE, for example, to determine the quality of the channel resource(s) for one or more users. Typically, in response to CSI feedback, the eNodeB can select from QPSK, 16-QAM and 64-QAM schemes and a wide range of code rates. This CSI information may be used to assist the multi-user scheduling algorithm in assigning channel resources to different users or adapting link parameters such as modulation scheme, coding rate, or transmission power so as to use the assigned channel resources to its fullest potential.

The CSI is reported for each component carrier and, depending on the reporting method and frequency band, for different sets of component carrier subbands. In 3GPP LTE, the smallest unit for which the channel quality is reported is called a sub-band, which consists of a plurality of frequency contiguous resource blocks.

As previously described, user equipments will typically not perform and report CSI measurements on configured but disabled downlink component carriers, but only measurements related to radio resource management, such as RSRP (reference received power) and RSRQ (reference received quality). ).

Typically, mobile communication systems define a special control signaling that is used to send channel quality feedback. In 3GPP LTE, there are three main elements that may or may not be specified as feedback for channel quality. These channel quality elements are:

- MCSI: Modulation and Coding Scheme Indicator, sometimes referred to as Channel Quality Indicator (CQI) in the LTE specification

- PMI: precoding matrix pointer

- RI: rank indicator.

MCSI proposes a modulation and coding scheme to be used for transmission, while PMI specifies a precoding matrix/vector to be used for spatial multiplexing and multi-antenna transmission (MIMO) using the rank of the transmission matrix, which is specified by RI. Details of the reporting and transmission mechanisms under consideration are given in the following specifications, which are referred to for further reading (all documents are available at htt://www.3gpp.org, and incorporated herein by reference):

- TS 36.211 3GPP “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation”, version 10.0.0, in particular sections 6.3.3, 6.3.4,

- TS 36.212 3GPP “Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and coding channel”, version 10.0.0, in particular sections 5.2.2, 5.3.3,

- TS 36.213 3GPP “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”, version 10.0.1, in particular sections 7.1.7 and 7.2.

In 3GPP LTE, not all of the above identified three channel quality elements are reported at any given time. The actual reported items mainly depend on the configured reporting mode. It should be noted that 3GPP LTE also supports the transmission of two codewords (i.e., two codewords of user data (transport blocks) can be multiplexed into one subframe and transmitted in it), such that feedback can be given for either one, or for two code words. Separate reporting modes for aperiodic channel quality feedback are defined in 3GPP LTE.

Both the periodicity and frequency resolution used by the UE to report CSI are controlled by the eNodeB. The Physical Uplink Control Channel (PUCCH) is only used for periodic CSI reporting (i.e., CSI messages at a given frequency configured by RRC), PUSCH is used for aperiodic CSI reporting, with the eNodeB specifically commanding (using PDCCH ) by the UE to send a separate CSI message inserted in a resource that is scheduled for uplink data transmission.

In addition, in the case of multiple transmission antennas in the eNodeB, CSI value(s) may be reported for the second codeword. For some downlink transmission modes, additional reverse link signaling consisting of precoding matrix indicators (PMI) and rank indicators (RI) may also be transmitted by the UE.

In order to quickly obtain CSI information, the eNodeB may schedule aperiodic CSI by setting the CSI request bit in the uplink resource grant transmitted on the downlink physical control channel.

In 3GPP LTE, a simple mechanism is envisaged to trigger the so-called aperiodic channel quality feedback from the user equipment. The eNodeB in the radio access network transmits an L1/L2 control signal to the user equipment to request the transmission of a so-called aperiodic CSI message (for details see 3GPP TS 36.212 section 5.3.3.1.1 and 3GPP TS 36.213 section 7.2.1). Another possibility to initiate provision of aperiodic channel quality feedback by user equipments is related to the random access procedure (see 3GPP TS 36.213, section 6.2).

Whenever a trigger event for providing channel quality feedback is received by the user equipment, the user equipment then sends the channel quality feedback to the eNodeB. Typically, the channel quality feedback (i.e., the CSI message) is multiplexed with the uplink (user) data in the physical uplink shared channel (PUSCH) resources that have been assigned to the user equipment by L1/L2 signaling by a scheduler. (eNodeB). In the case of carrier aggregation, the CSI message is multiplexed on these PUSCH resources that were provided with the L1/L2 signal (ie, PDCCH) that triggered the channel quality feedback.

Sounding reference symbol (SRS)

The SRSs are important for uplink channel sounding to support dynamic uplink resource assignment as well as beamforming with uplink reciprocity. Version 10 introduces the ability to dynamically initiate individual SRS transmissions over the PDCCH, these dynamic aperiodic SRS transmissions are known as "type-1" SRS, while the periodic SRS configured by RRC version 8 are referred to as "type-0" in version 10.

The pointer in the uplink resource grant on the PDCCH can be used to initiate a single Type 1 SRS transmission. This facilitates fast channel sounding to respond to traffic or channel state changes without consuming SRS resources over a long period. In DCI format 0, one new bit may indicate activation of SRS type 1 according to the setting of parameters that are configured in advance with RRC signaling. In DCI format 4, which is used for scheduling uplink SU-MIMO transmissions, two new bits allow one of the three sets of type 1 SRS transmission parameters configured by RRC to be triggered.

SRS transmissions are always in the last SC-FDMA symbol of the corresponding subframe where the message is configured/scheduled. PUSCH data transmission is not allowed in the SC-FDMA signal intended for SRS, ie, the PUSCH transmission is punctured such that all symbols except the last one are used for PUSCH.

Uplink control signaling and multiplexing

When uplink PUSCH data and control signaling are scheduled at the same time, control signaling is typically multiplexed along with data (on the PUSCH) prior to DFT spreading in order to keep low Cubic Metric (CM) performance from one uplink transmission carrier. The uplink control channel, PUCCH, is used by the UE to transmit any necessary control signaling only in subframes in which the UE has not been assigned any RBs for PUSCH transmission.

Additional information regarding uplink control signaling multiplexing can be found in chapters 16.3.1.1, 16.3.3, 16.3.4, 16.3.5, 16.3.6, 16.3.7, 16.4 LTE-UMTS Long Term Evolution -From Theory to Practice , Edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Second Edition, incorporated herein by reference.

DRX (Discontinuous Reception)

In order to provide moderate battery consumption of user equipment, 3GPP LTE (release 8/9) as well as 3GPP LTE-A (release 10) provides the concept of Discontinuous Reception (DRX). Technical standard TS 36.321 chapter 5.7 explains DRX, and is incorporated herein by reference.

The following parameters are available to define the behavior of the UE DRX, i.e., the periods in which the mobile node is active (i.e., active time) and the periods in which the mobile node is inactive (i.e., inactive time, while in DRX mode).

- ON duration (timer): the duration in downlink subframes when the user equipment, upon wakeup from DRX (Inactive Time), receives and monitors the PDCCH. If the user equipment successfully decodes the PDCCH, the user equipment remains awake and starts the DRX inactivity timer, (1-200 subframes, 16 steps: 1-6, 10-60, 80, 100, 200).

- DRX inactivity timer: duration in downlink subframes when the user equipment waits to successfully decode the PDCCH from the last successful PDCCH decoding, when the UE fails to decode the PDCCH within this period, it re-enters DRX. The user equipment will restart the DRX sleep timer after one successful PDCCH decoding for the first transmission only (ie, not for retransmissions). (1-2560 subframes, 22 stages, 10 reserves: 1-6, 10-60, 80, 100-300, 500, 750, 1280, 1920, 2560).

- DRX retransmission timer: specifies the number of consecutive PDCCH subframes where downlink transmission is expected by the UE after the first available transmission time. (1-33 subframes, 8 stages: 1, 2, 4, 6, 8, 16, 24, 33).

- short DRX cycle: specifies a periodic repetition of the on duration followed by a possible period of inactivity during the short DRX cycle. This parameter is optional. (2-640 subframes, 16 stages: 2, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640).

- DRX short cycle timer: specifies the number of consecutive subframes in which the UE adheres to the DRX short cycle after the DRX inactivity timer has expired. This parameter is optional (1-16 subframes).

- DRX long cycle start offset: specifies the periodic repetition of the on duration followed by a possible period of inactivity during the long DRX cycle, as well as the offset in subframes when the on duration starts (defined in the formulas defined in TS 36.321 section 5.7) , (10-2560 cycle duration subframes, 16 steps: 10, 20, 30, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640, 1024, 1280, 2048, 2560, offset is integer from (0 is the length of the subframe of the selected cycle).

The total duration when the UE is awake is referred to as "active time". The active time includes the DRX cycle on duration time, the time when the UE performs continuous reception while the DRX inactivity timer has not expired, and the time when the UE performs continuous reception while waiting for downlink retransmission. communication after one RTT HARQ. Similarly, for uplink, the UE wakes up in subframes where uplink retransmission grants can be received, i.e., every 8ms after the initial uplink transmission until the maximum number of retransmissions is reached. Based on the above, the minimum active time is equal to the duration equal to the duration of the on state, and the maximum is undefined (infinite). In addition, also after transmitting the SR on the PUCCH, the UE will wake up monitoring the PDCCH assigning back the UL-SCH, the idle time is essentially the duration of the downlink subframes during which the UE may skip receiving downlink channels to save battery.

The DRX operation allows the mobile terminal to periodically deactivate the radio channels (according to the current active DRX cycle) in order to save power. Whether or not the UE actually stays idle (i.e., is inactive) during the DRX period may be decided by the UE, e.g., the UE typically performs inter-frequency measurements that cannot be taken during the on-state duration, and thus must be performed at some other time.

The parameterization of the DRX cycle involves a trade-off between battery saving and latency. On the other hand, a long DRX period is useful for extending the battery life of the UE. For example, in the case of a web browsing service, there is usually a waste of resources for the UE to continuously receive downlink channels while the user is reading a loaded web page. On the other hand, a shorter DRX period is better for faster response when data transmission resumes, such as when the user requests another web page.

To satisfy these conflicting requirements, two DRX cycles, a short cycle and a long cycle, may be configured per UE. The transmission between DRX short cycle, DRX long cycle and continuous reception is controlled either by a timer or by explicit commands from the eNB. In a sense, the short DRX cycle can be considered as an acknowledgment period, in the case of late packet arrivals, before the UE enters the long DRX cycle, if data arrives at the eNB while the UE is in the short DRX cycle, data is scheduled for transmission. at the next wake-up time, and the UE then resumes continuous reception. On the other hand, if no data arrives at the eNB during the short DRX cycle, the UE enters the long DRX cycle, assuming that the burst activity ends for the time being.

The available DRX values are managed by the network and start with no DRX up to x seconds. The x value may be equal in duration to the paging DRX used in the idle state. The requirement criteria and measurement messages may differ according to the length of the DRX interval, i.e., long intervals may experience more relaxed requirements.

When DRX is configured, periodic CQI/SRS messages will only be transmitted by the UE during "active time". The RRC may further restrict the periodic CQI messages such that they are only transmitted during the duration of the on state.

In FIG. 8 shows an example of a DRX cycle per frame. The UE checks for scheduling messages (indicated by its C-RNTI on the PDCCH) during the "On Duration" period of either a long DRX cycle or a short DRX cycle, depending on the current active cycle. When a scheduling message is received during the "On Duration", the UE starts the "Inactivity Timer" and monitors the PDCCH in each subframe while the inactivity timer is running. During this period, the UE may be considered to be in continuous reception mode. Whenever a scheduling message is received while the inactivity timer is running, the UE restarts the inactivity timer, and when it expires, the UE enters the DRX short cycle and starts the "DRX short cycle timer". The short DRX cycle can also be initiated by the DRX MAC control from the eNodeB instructing the UE to enter DRX. When the short DRX cycle timer expires, the UE transitions to the long DRX cycle. In addition to this DRX behavior, a "HARQ round trip time (RTT) timer" is defined to allow the UE to be in sleep mode during the HARQ RTT. When the downlink transport block decoding for one HARQ process fails, the UE may assume that the next transport block retransmission will occur after at least "RTT HARQ" subframes. While the RTT HARQ timer is running, the UE is not required to monitor the PDCCH. When the RTT HARQ timer expires, the UE resumes receiving the PDCCH as usual.

The aforementioned DRX-related timers, such as the DRX inactivity timer, the RTT HARQ timer, the DRX retransmission timer, and the DRX short cycle timer, are started and stopped by events such as the receipt of a PDCCH grant or a MAC control element (DRX MAC CE), therefore, the DRX status (active time or inactive time) of the UE may change from one subframe to another and hence is not always predictable by the mobile station or the eNodeB.

There is only one DRX cycle per UE. All aggregate component carriers follow this DRX pattern.

Disadvantages of modern periodic CSI/SRS reporting during DRX

As mentioned above, the DRX status (ie, active time/inactive time) of the UE may change from subframe to subframe. DRX related timers (DRX inactivity timer, HARQ RTT timer, DRX retransmission timer) are started and stopped by various events such as receiving a PDCCH grant or MAC control elements (DRX MAC CE), thus setting the UE to active time or during inactive hours. The behavior of the UE for active time and idle time is clearly defined by the standard. Thus, the UE will only transmit periodic CSI and SRS messages during active time. However, the UE takes some time to process the received signaling or information changing its status, and also takes some time to prepare the CSI and SRS message. The processing time is highly dependent on the implementation of the UE. However, this may lead to problems during operation of the UE, as will be explained in detail below.

Assuming that the UE is currently in active time and a DRX sleep timer is running, if the UE receives in the last subframe before the DRX sleep timer expires (e.g., subframe N) a PDCCH indicating a new transmission (UL or DL), the UE will also be in active time in the next subframe, i.e., N+1 subframe, and the DRX inactivity timer is restarted.

Due to the processing time at the UE, the UE may now only be at the beginning/middle of the N+1 subframe when the N+1 subframe is still active time. Assuming that a periodic CSI message is configured to be transmitted in an N+1 subframe, the UE may not have time to prepare the CSI message for transmission, since it is assumed that it originally entered DRX, i.e., is inactive time during the subframe N+1, and thus need not send a CSI message. As a result, the UE could not transmit the periodic CSI message in the N+1 subframe, contrary to the specification requiring the UE to transmit the periodic CSI on the PUCCH during the active time in the configured subframes.

Finally, the behavior of the UE regarding CSI/SRS transmission may not immediately follow the DRX status of the UE because it takes some time for the UE to learn about the signaling and prepare the necessary uplink transmission accordingly. The time after active time, which suddenly started/continued or ended, due to the receipt of the appropriate signaling from the network, is commonly referred to as a "transitional phase" or "indefinite period". In order to account for the processing delay at the UE, an exception regarding periodic CSI transmission on PUCCH and periodic SRS transmission was introduced for Rel-8/9/10 LTE TS 36.321 as follows.

The UE may optionally choose not to send CQI/PMI/RI/PTI messages on the PUCCH and/or send type 0 triggered SRS messages for up to 4 subframes after the PDCCH indicates a new transmission (UL or DL) received in subframe n- 1, where n is the last active time subframe and i is an integer value from 0 to 3. After the active time ends due to the reception of a PDCCH or a MAC control element, the UE may optionally choose to continue transmitting CQI/PMI/ RI/PTI in PUCCH and/or SRS transmissions for up to 4 subframes. The choice to not send CQI/PMI/RI/PTI messages on the PUCCH and/or triggered Type 0 SRS transmissions is not applicable for subframes where the on-duration timer is running, and is not applicable for sub-carts n-i to n.

Despite the above exception, the eNB normally waits for the uplink transmission from the UE in accordance with the specification. Thus, regarding the CSI/SRS message when the UE is in active time, the UE is expected to send periodic CSI messages on PUCCH and SRS depending on the CSI/SRS periodicity. Thus, the eNB does not expect any periodic CSI/SRS transmission from the UE in subframes where the UE is in idle time.

However, due to the behavior of the UE introduced to cover "transition phases", the behavior of the UE during these "transition phases" is unpredictable for the eNB. As a result, the network must be able to correctly decode the PUCCH or PUSCH for cases where it does not know whether periodic CSI or SRS messages have been transmitted or not. In other words, dual decoding is needed at the UE to cover both transmission cases, ie, with or without CSI/SRS. For example:

- if the CSI happens to coincide with the PUCCH HARQ DL transmission in the transition phase, then the network needs to perform dual decoding to deal with both the case when the CSI was transmitted and the case when the CSI was not transmitted.

- if the SRS coincidentally coincides with a PUCCH HARQ DL transmission that is outside the configured SRS bandwidth in the transition phase, then the network needs to perform dual decoding to deal with both the case where the SRS was transmitted and the case where the SRS was not was transferred.

There are many more combinations of control information for which an eNB needs to perform double decoding for two different transmission formats in order to be able to correctly detect the control information. Some of these combinations are given in the table below, which is taken from R2-124687, it should be noted that the list is not exhaustive, but will give a general idea.

Case (during which conflicts are possible) If CSI/SRS is transmitted If CSI/SRS is not transmitted Double decoding required? (transition phase) CSI+data Data (RMed)+CSI Data Yes CSI+AN CSI+AN (jointly encoded) AN Yes CSI+SR SR (CSI discarded) SR Not CSI+data+AN Data(RMed)+CSI Data Yes CSI+data+SR [CSI& multiplexed data] (RMed)+AN Data(RMed)+AN Yes CSI+AN+SR AN+SR AN+SR Not CSI+data+AN+SR [CSI& multiplexed data] (RMed)+AN Data(RMed)+AN Yes SRS+data Data(RMed)+SRS Data Yes SRS+AN [AN (short format)+SRS] or AN (regular format) AN (short format) or AN (regular format) Not SRS+SR [SR (Short Format)+SRS] or SR (Regular Format) [SR (Short Format)+SRS] or SR (Regular Format) Not SRS+data+SR Data(RMed)+SRS Data Yes SRS+data+AN Data (RMed via AN/SRS)+AN+SRS Data (RMed via AN)+AN Yes SRS+AN+SR [AN+SR] (short format)+SRS or [AN+SR] (regular format) [AN+SR] (short format) or [AN+SR] (regular format) Not SRS+data+AN+SR Data(RMed via AN)+AN+SRS Data(RMed via AN)+AN Yes CSI+SRS+data Data(RMed via CSI/SRS)+CSI+SRS Data(RMed via CSI)+CSI Yes CSI+SRS+AN AN(short format)+SRS or AN(regular format) AN(short format) or AN(regular format) Not CSI+SRS+SR SR(short format)+SRS SR (shortened format) Not CSI+SRS+data+SR
CSI+SRS+data+AN Data(RMed via CSI/SRS)+CSI+SRS
[CSI&multiplexed data] (RMed over AN/SRS)+AN+SRS Data(RMed via CSI)+CSI
(RMed via AN)+AN Yes CSI+SRS+AN+SR AN+SR(short format)+SRS AN+SR(regular format) Yes CSI+SRS+data+AN+SR [CSI&multiplexed data] (RMed over AN/SRS)+AN+SRS Data(RMed via AN)+AN Yes

As can be seen, the double decoding caused by the transition phases could happen quite often and cause unnecessary complexity and computational cost in the network. Decoding in the eNB depends on uplink transmissions having a specific transmission format such as format 2, 2a and 2b always including CSI. When the transmission format is changed due to sudden transmission or CSI retransmission, decoding at the UE may fail due to an incorrect transmission format, which in turn results in performance degradation.

This applies in a similar way to SRS transmission. Assuming that the assigned resource blocks for PUSCH do not overlap with the cell-specific SRS frequency domain, in case the UE does not transmit SRS in this subframe, the UE uses the last SC-FDMA symbol in the subframe for PUSCH. In the case where the UE transmits the SRS in this subframe, the UE does not use the last SC-FDMA symbol for PUSCH. Therefore, depending on whether the UE transmits SRS (which depends on the DRX status of the subframe), the number of SC-FDMA symbols for PUSCH is changed, which in turn means that the eNB would not have to check the use of two different PUSCH symbols in these subframes. However, this ambiguity can be easily avoided by the eNB by assigning only PUSCH resources to UEs that are located in the cell-specific SRS region, which is most assignments, in which case the UE will never display PUSCH in the last SC-FDMA symbol in the subframe, where the periodic SRS has been configured. However, the problem remains for the case where the assigned resource blocks for the PUSCH are not located in the cell-specific SRS region.

The essence of the invention

It is an object of the invention to provide deterministic UE behavior for CSI and/or SRS transmission that solves the problems of the prior art as discussed above.

The problem is solved by means of the subject matter of the independent claims. Preferred embodiments fall within the dependent claims.

The present invention provides a method according to the first embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in an N subframe. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and /or periodic sounding reference symbols. It is determined whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N-4, and

DRX associated timers running for the mobile station, including at least one of a DRX inactivity timer, a DRX on duration timer, and a DRX retransmission timer.

The mobile station transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N when it is determined that the mobile station is in DRX active time in subframe N.

According to an advantageous embodiment of the first embodiment of the invention, which may be used in addition to or as an alternative to the above, the base station performs the steps:

determining whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel transmitted to the mobile station only before and during subframe N-4, and

DRX-related timers running for the mobile station, including at least one of a DRX inactivity timer, a DRX on duration timer, and a DRX retransmission timer,

receiving a channel quality information message and/or a sounding reference symbol from the mobile station in subframe N, when it is determined by the determination step that the mobile station is in DRX active time in subframe N.

According to an advantageous embodiment of the first embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination is further based on MAC control elements related to the DRX operation received by the mobile station only before and during the N-(4+k) subframe , where k is an integer from 1 to K. Alternatively, the determination is further based on MAC control elements related to the DRX operation for which an acknowledgment is transmitted by the mobile station only up to and including the N-(3+k) subframe, where k is an integer from 1 to K. In accordance with an advantageous embodiment of the first embodiment of the invention, which may be used in addition to or as an alternative to the above, timers associated with DRX are taken into account in the determination based on shared channel uplink resource grants. uplink and/or destinations downlink pc for the downlink shared channel received by the mobile station only before and during subframe N-4, and additionally based on the value of timers associated with DRX in subframe N-4.

The present invention provides a mobile station of the first embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in an N subframe. The N subframe is configured for the mobile station to transmit periodic channel quality information messages. and/or periodic sounding reference symbols. The mobile station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N-4, and

DRX associated timers running for the mobile station, including at least one of a DRX inactivity timer, a DRX on duration timer, and a DRX retransmission timer.

The mobile station transmitter transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the processor that the mobile station is in DRX active time in subframe N.

According to the mobile station's advantage of the first embodiment, which may be used in addition to or as an alternative to the above, the processor performs a determination further based on the MAC control elements related to the DRX operation received by the mobile station only before and during subframe N -(4+k), where k is an integer from 1 to K. Alternatively, the processor makes a determination further based on the DRX operation-related MAC controls for which an acknowledgment is transmitted by the mobile station only up to and including subframe N -(3+k), where k is an integer value from 1 to K. The present invention provides a base station of the first embodiment for receiving a channel quality information and/or sounding reference symbol message from a mobile station of a mobile communication system in an N subframe. N is configured for the mobile station to transmit periodic messages. communication of channel quality information and/or periodic sounding reference symbols. The base station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel transmitted to the mobile station only before and during subframe N-4, and

DRX associated timers running for the mobile station, including at least one of a DRX inactivity timer, a DRX on duration timer, and a DRX retransmission timer.

The base station receiver receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N in the case where it is determined by the processor that the mobile station is in DRX active time in subframe N.

The present invention provides a method according to a second embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in an N subframe. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and /or periodic sounding reference symbols. It is determined whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on MAC control elements related to the DRX operation received by the mobile station only before and during subframe N-(4+ k), where k is an integer from 1 to K. The mobile station transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the determining step that the mobile station is in active time DRX in subframe N. According to an advantageous variant of the method of the second embodiment, which may be used in addition to or alternatively to the above, the base station determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N , at least based on the MAC control elements related to the DRX operation transmitted to the mobile station m only before and during the N-(4+k) subframe, where k is an integer from 1 to K, and based on feedback received from the mobile station related to decoding success for MAC control elements. The base station receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N when it is determined by the determination step that the mobile station is in DRX active time in subframe N.

In accordance with an advantageous variant of the method of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination ignores any DRX operation related MAC controls intended for the mobile station in subframes from N-(3+k) to N.

According to an advantageous embodiment of the method of the second embodiment, which may be used in addition to or as an alternative to the above, the mobile station does not transmit a channel quality information message and/or a sounding reference symbol to the base station in subframe N, in the case where it is determined with the step of determining that the mobile station is in the DRX sleep time in subframe N.

According to an advantageous embodiment of the method of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination is further based on uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the shared channel. downlink channels received by the mobile station only before and during subframe N-4. Alternatively, the determination is further based on uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N-(4+ k).

In accordance with an advantageous variant of the method of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination is further based on DRX related timers running for the mobile station, including at least one of the DRX sleep timer, DRX On Duration Timer; and DRX Retransmission Timer.

In accordance with an advantageous variant of the method of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination comprises the step of estimating the state of the DRX-related timers in subframe N based on the uplink resource grants for the uplink shared channel. links and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N-4, and further based on the value of timers associated with DRX in subframe N-4.

According to an advantageous embodiment of the method of the second embodiment, which may be used in addition to or as an alternative to the above, the mobile station transmits an acknowledgment or a negative acknowledgment in subframe N-k for a MAC control element related to a DRX operation received by the mobile station in subframe N-(4+k). The mobile station transmits an acknowledgment or a negative acknowledgment in subframe N for the MAC control related to the DRX operation received by the mobile station in subframe N-4.

According to an advantageous embodiment of the method of the second embodiment, which may be used in addition to or as an alternative to the above, the determination step processing is started at the mobile station in the N-(4+k) subframe, and after the determination step process is completed, the preparation by the mobile station is started. channel quality and/or sounding reference symbol messages to be transmitted in subframe N for the transmission step.

The present invention provides a mobile station of the second embodiment for transmitting a channel quality information message and/or a sounding reference symbol to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and/or periodic probing reference symbols. The mobile station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on MAC control elements related to the DRX operation received by the mobile station only before and during subframe N- (4+k), where k is an integer value from 1 to K. The mobile station transmitter transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the processor that the mobile station is in active DRX time in subframe N.

In accordance with the mobile station's preferred embodiment of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the processor ignores any DRX operation-related MAC controls intended for the mobile station in subframes from N-(3+k) to N.

According to an advantageous embodiment of the mobile station of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the processor makes a determination further based on the uplink resource assignments for the uplink shared channel and/or the downlink resource assignments. for the downlink shared channel received by the mobile station only before and during the N-4 subframe. Alternatively, the processor makes a determination further based on the uplink resource assignments for the uplink shared channel and/or the downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N- (4+k).

In accordance with an advantageous embodiment of the mobile station of the second embodiment of the invention, which may be used in addition to or as an alternative to the above, the processor performs a determination further based on DRX-related timers running for the mobile station, including at least one of DRX inactivity timer, DRX on duration timer, and DRX retransmission timer.

According to the mobile station's advantageous embodiment of the second embodiment, which may be used in addition to or as an alternative to the above, the processor makes a determination comprising the step of estimating the state of the DRX-related timers in subframe N based on the uplink resource grants for jointly of the used uplink channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N-4, and additionally based on the value of timers associated with DRX in subframe N-4 .

The present invention provides a base station of the second embodiment for receiving a channel quality information message and/or a sounding reference symbol from a mobile station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and/or periodic probing reference symbols. The base station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on the DRX operation-related MAC control elements transmitted to the mobile station only before and during subframe N -(4+k), where k is an integer from 1 to K, and based on feedback received from the mobile station related to decoding success for the transmitted MAC control elements. The base station receiver receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N in the case where it is determined by the processor that the mobile station is in DRX active time in subframe N.

The present invention provides a method according to a third embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in an N subframe. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and /or periodic sounding reference symbols. Whether the mobile station will be in DRX active time or DRX inactive time in subframe N is determined at least based on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to K, and

MAC control elements related to the DRX operation received by the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to K.

The mobile station transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N when it is determined by the determination step that the mobile station is in DRX active time in subframe N.

According to an advantageous embodiment of the method of the third embodiment, which may be used in addition to or as an alternative to the above, the base station determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N for at least based:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel transmitted to the mobile station only before and during the N-(4+k) subframe, where k is an integer a value from 1 to K, and

MAC control elements related to the DRX operation transmitted to the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to K.

The base station receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N when it is determined by the determination step that the mobile station is in DRX active time in subframe N.

According to an advantageous variant of the method of the third embodiment, which may be used in addition to or as an alternative to the above, the determination is further based on DRX-related timers running for the mobile station, including at least one of the DRX sleep timer, DRX On Duration Timer; and DRX Retransmission Timer. Preferably, the determination then comprises estimating the state of the DRX-related timers in subframe N based on the uplink resource assignments for the uplink shared channel and/or the downlink resource assignments for the downlink shared channel received by the mobile station just before and during subframe N-4, and further based on the value of timers associated with DRX in subframe N-4.

The present invention provides a mobile station in a third embodiment for transmitting a channel quality information message and/or sounding reference symbols from a mobile station to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages. and/or periodic sounding reference symbols. The mobile station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to k, and

MAC control elements related to the DRX operation received by the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to K.

The mobile station transmitter transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the processor that the mobile station is in DRX active time in subframe N.

According to the mobile station's preferred embodiment of the third embodiment, which may be used in addition to or as an alternative to the above, the processor performs a determination further based on DRX-related timers running for the mobile station, including at least one of DRX inactivity timer, DRX on duration timer, and DRX retransmission timer.

The present invention also provides a base station of the third embodiment for receiving a channel quality information message and/or a sounding reference symbol from a mobile station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and/or or periodic sounding reference symbols. The base station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N based at least on:

uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel transmitted to the mobile station only before and during the N-(4+k) subframe, where k is an integer a value from 1 to K, and

MAC control elements related to the DRX operation transmitted to the mobile station only before and during the N-(4+k) subframe, where k is an integer value from 1 to K.

The base station receiver receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N in the case where it is determined by the determining step that the mobile station is in DRX active time in subframe N.

The present invention further provides a method according to the fourth embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages. and/or periodic sounding reference symbols. It is determined whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on the MAC control elements related to the DRX operation for which an acknowledgment is transmitted by the mobile station only up to and during subframe N -(3+k), where k is an integer value from 1 to K. The mobile station transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the determination step that the mobile station is in active DRX time in subframe N.

According to an advantageous embodiment of the method of the fourth embodiment, which may be used in addition to or as an alternative to the above, the base station determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N of at least based on the MAC control elements related to the DRX operation, for which the acknowledgment is received by the mobile station only before and during the N-(3+k) subframe, where k is an integer value from 1 to K. The base station receives the channel quality information message and/or a sounding reference symbol from the mobile station in subframe N in the case where it is determined by the determining step that the mobile station is in DRX active time in subframe N.

In accordance with an advantageous embodiment of the method of the fourth embodiment of the invention, which may be used in addition to or as an alternative to the above, the determination is further based on DRX-related timers running for the mobile station, including at least one of the DRX sleep timer, DRX On Duration Timer; and DRX Retransmission Timer. Preferably, this may be done by estimating the state of the DRX-related timers in subframe N based on the uplink resource assignments for the uplink shared channel and/or the downlink resource assignments for the downlink shared channel received by the mobile. by the station only up to and during subframe N-4, and additionally based on the value of the DRX-related timers in subframe N-4.

In accordance with an advantageous embodiment of the method of the fourth embodiment of the invention, which may be used in addition to or as an alternative to the above, the definition ignores any MAC control elements related to the DRX operation for which an acknowledgment is transmitted by the mobile station in subframes from N-(2+ k) to N.

According to an advantageous embodiment of the method of the fourth embodiment of the invention, which may be used in addition to or alternatively to the above, the determination is further based on uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the shared channel. downlink channels received by the mobile station only before and during subframe N-4.

The present invention further provides the mobile station of the fourth embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic quality information messages. channel and/or periodic sounding reference symbols. The mobile station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on the MAC control elements related to the DRX operation for which the acknowledgment is transmitted by the mobile station before and during subframe N-(3+k), where k is an integer from 1 to K. The mobile station transmitter transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where it is determined by the processor that the mobile station is in active DRX time in subframe N.

According to the mobile station's preferred embodiment of the fourth embodiment, which may be used in addition to or as an alternative to the above, the processor performs a determination further based on DRX-related timers running for the mobile station, including at least one of DRX inactivity timer, DRX on duration timer, and DRX retransmission timer. Alternatively, the processor makes a determination further based on the uplink resource assignments for the uplink shared channel and/or the downlink resource assignments for the downlink shared channel received by the mobile station only before and during subframe N- four.

According to the mobile station's advantageous embodiment of the fourth embodiment, which may be used in addition to or as an alternative to the above, the processor performs the determination by ignoring the DRX operation related MAC control elements for which the acknowledgment is transmitted by the mobile station in subframes from N -(2+k) to N.

The present invention further provides the base station of the fourth embodiment for receiving a channel quality information message and/or a sounding reference symbol from a mobile station of the mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and/or periodic probing reference symbols. The base station processor determines whether the mobile station will be in DRX active time or DRX inactive time in subframe N at least based on the MAC control elements related to the DRX operation for which an acknowledgment is received from the mobile station only up to and during subframe N-(3+k), where k is an integer from 1 to K. The base station receiver receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N in the case where determined by step determining that the mobile station is in active DRX time in subframe N.

The present invention further provides a method according to the fifth embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages. and/or periodic sounding reference symbols. The mobile station transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N when the mobile station is in DRX active time in subframe N-k, where k is an integer value from 1 to K.

The present invention further provides the mobile station of the fifth embodiment for transmitting a channel quality information message and/or a sounding reference symbol from a mobile station to a base station in a mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic quality information messages. channel and/or periodic sounding reference symbols. The mobile station transmitter transmits a channel quality information message and/or a sounding reference symbol to the base station in subframe N in the case where the mobile station is in DRX active time in subframe N-k, where k is an integer value from 1 to K, where k is an integer value from 1 to K.

The present invention further provides the base station of the fifth embodiment for receiving a channel quality information message and/or a sounding reference symbol from a mobile station of the mobile communication system in subframe N. The N subframe is configured for the mobile station to transmit periodic channel quality information messages and/or periodic probing reference symbols. The base station receiver receives the channel quality information message and/or the sounding reference symbol from the mobile station in subframe N when the mobile station is in DRX active time in subframe N-k, where k is an integer value from 1 to K.

Brief description of the drawings

In the following, the invention is described in more detail with reference to the accompanying drawings.

Fig. 1 depicts an exemplary 3GPP LTE system architecture,

fig. 2 depicts an illustrative overview of the overall E-UTRAN architecture,

fig. 3 depicts exemplary subframe boundaries in a downlink component carrier as defined for 3GPP LTE,

Fig. 4 depicts an exemplary downlink resource grid of a downlink slot as defined for 3GPP LTE (release 8/9),

fig. 5 and FIG. 6 shows the 3GPP LTE-A (Release 10) layer structure with carrier aggregation enabled for downlink and uplink, respectively,

fig. 7 depicts a state diagram for a mobile terminal, and in particular the RRC_CONNECTED and RRC_IDLE states, and the functions performed by the mobile terminal in these states,

fig. 8 illustrates the mobile terminal's DRX operation and, in particular, the capability of DRX, duration on, according to short and long DRX cycles,

fig. 9 - fig. 12 are subframe diagrams illustrating the operation of the mobile terminal and the base station for the first embodiment for various scenarios depending on the subframe in which the PDCCH is received,

fig. 13 - fig. 14 are subframe diagrams illustrating the operation of the mobile terminal and the base station and the remaining uncertainty problem.

fig. 15 - fig. 16 are subframe diagrams illustrating the operation of a mobile terminal and a base station for the second embodiment.

fig. 17 - fig. 19 are subframe diagrams illustrating the operation of a mobile terminal and a base station for the fourth embodiment.

fig. 20 is a subframe diagram illustrating the operation of the mobile terminal and the base station for the fifth embodiment.

Detailed description of the invention

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

The term "DRX status" as used in the claims, as well as throughout the specification, refers to a mobile station that is either in "DRX active time" or "DRX idle time". "DRX active time" basically refers to the time during which the mobile station monitors the PDCCH and performs other tasks such as transmitting a periodic SRS and/or a periodic CSI, as configured. "DRX idle time" basically means the time during which the mobile station does not monitor the PDCCH and does not transmit the periodic SRS and/or periodic CSI.

The expression "only before and during subframe N-4" and similar expressions for N-(4+k) used in the claims, as well as throughout the description, will limit the subframes that must be considered for determination. Thus, the expression only applies to those subframes N-4, N-5, N-6, N-7, N-8, N-9, and so on. Thus, subframes N-3, N-2, N-1, and subframe N are not included according to the expression, and thus are ignored (discarded), i.e., not taken into account for determination. Another equivalent expression is "only subframes up to subframe N-3".

The expression "at subframe N-4" and similar expressions referring to other subframe indices used in the description are not necessarily to be understood to mean that the process (e.g., evaluation) is to be performed entirely in said specified subframe, but rather that the process begins in said specified subframe, and may safely proceed to the next subframes if the processing essentially takes longer to be completed. This, of course, depends in part on the implementation of the mobile station or base station performing the above process.

In the following, several embodiments of the invention will be explained in detail. The explanations are not to be understood as limiting the invention. A person skilled in the art should be aware that the general principles of the invention, as set forth in the claims, may apply to other scenarios and methods that are not expressly described in this application. Thus, the following scenarios, taken for explanatory purposes of the various embodiments, are not intended to limit the invention as such.

One main aspect of the invention is to make a determination as to whether or not to transmit the CSI/SRS in a deterministic manner, ie, whether the result of the determination can be determined in advance, or, to put it another way, no ambiguity is involved.

For the following embodiments of the invention, it is assumed that subframe N is configured for a periodic CSI/SRS message. For ease of explanation, it is assumed that the periodic CSI and the periodic SRS are configured for the same subframe (ie, subframe N), however, this is not necessarily always true. Embodiments of the invention can be successfully applied to cases where periodic CSI and SRS are configured for different subframes, in these cases, embodiments of the invention should be applied separately for CSI and SRS.

In addition, the figures discussed below to explain various embodiments of the invention assume an ideal situation where the processing time in the UE/eNodeB is negligible and is not taken into account for purposes of illustration. Of course, in a real-world implementation, the UE and the eNodeB require a certain processing time (eg, several subframes) to properly decode the downlink transmission and process the decoded information appropriately. For example, after receiving the DRX MAC CE command to enter DRX, it is assumed that the UE immediately enters the RRX mode in the next subframe according to the standard, however, in reality this will not be possible because the UE will take time to process the DRX MAC CE, and it may enter DRX, for example, with a delay of 2 subframes.

First Embodiment

According to the first set of embodiments, instead of acting according to the DRX status during actual downlink transmission, the UE estimates in subframe N-4 the DRX status of the subframe that is 4 subframes ahead (i.e., subframe N), and decides, based on the estimated status, whether or not to transmit the periodic CSI/DRX. For estimation, the UE considers all PDCCHs (i.e., uplink resource grants and/or downlink resource assignments) that are received up to subframe N-4 (having a possible impact on the DRX status of the UE for subframe N), but does not consider no PDCCHs received after subframe N-4, i.e., in subframes N-3, N-2, N-1 and N. The reason why the UE looks 4 subframes ahead is that it meets the same requirements timing, as defined in the above exception regarding periodic CSI transmission in PUCCH and periodic SRS transmission introduced for Rel-8/9/10 LTE in TS 36.321.

In addition, the estimation is based not only on UL grants/DL assignments as just mentioned, but also based on at least the DRX associated timer(s) running for the mobile station during subframe N, such as the inactivity timer, an on state duration timer and/or a retransmission timer. The DRX timers generally have a direct impact on the DRX status of a subframe, ie, whether or not the UE is in active time in subframe N. Not all timers may run at the same time. In addition, not all of the DRX timers configured for the mobile station should actually be taken into account, only a subset (eg, one DRX timer) of the DRX timers might be taken into account. For example, it would be possible to only consider the on-state duration timer and not the retransmission timer, even if it is currently running, when determining whether or not to transmit the CSI/SRS.

In particular, the UE estimates the values and status of the DRX timer(s) in subframe N, and thus anticipates whether it will be active or not in subframe N, depending on the estimated status/value of the DRX timer in subframe N. Of course, only those timers associated with DRX should preferably be taken into account, the value of which in subframe N can be extrapolated already in subframe N-4.

However, again, the UE only considers those DRX timers whose value in subframe N is already known in subframe N-4, e.g., the UE knows already in subframe N-4 based on grants/assignments received before and during subframe N-4 that the ON duration/retransmission timer is executed in subframe N, in case the DRX timer value is reset or the DRX timer is aborted due to PDCCH reception or retransmission after subframe N-4 (e.g., in subframes N-3, N-2 , N-1, N), this is not taken into account for the evaluation. Thus, the estimate considering the timers associated with DRX is based on uplink resource assignments for the uplink shared channel and/or downlink resource assignments for the downlink shared channel received by the UE only before and during subframe N -4, and additionally based on an estimate of the status/values of the timers associated with DRX in subframe N.

By further considering the timer(s) associated with DRX, the accuracy of estimating whether subframe N is in active time or inactive time for the mobile station is increased, and hence the utility of the CSI/SRS is increased.

Typically, the UE will transmit CSI/SRS to the eNodeB in the case where subframe N is estimated to be DRX active, i.e., when the UE is in active time, based on the information explained above. On the other hand, the UE will not transmit CSI/SRS to the eNodeB in the case where subframe N is estimated to be inactive DRX, i.e., when the UE is in idle time, based on the information explained above. In both cases, the transmission of the CSI/SRS depends on the result of the estimation for the DRX status, but does not depend on the actual DRX status of the UE in subframe N, the latter status may be different from the estimated DRX status of the UE in subframe N. Thus, the UE could necessarily transmit CSI/ SRS even if the UE is awake in subframe N, or conversely, the UE does not transmit CSI/SRS even if the UE is awake in subframe N.

Estimation of the status of subframe N in advance, as explained above, is also performed in the eNodeB. Thus, the eNodeB having the same estimation information as the UE will receive the same estimation result, and thus knows whether the UE will transmit CSI/SRS or not in subframe N. Thus, the eNodeB will wait transmitting CSI/SRS by the UE in subframe N and thus will receive CSI/SRS if the evaluation is positive, or will not wait and will not attempt to receive CSI/SRS if the evaluation is negative. No more double decoding is needed in the eNodeB, resulting in less complexity in the eNodeB. Estimation, as explained, is deterministic and thus results in predictable estimation results for both the eNodeB and the UE.

In addition, this procedure essentially provides the UE 4 with subframes for PDCCH reception detection and CSI/SRS transmission preparation.

The above explanation will become clear in connection with the following FIGS. 9-fig. 12.

Fig. 9 and FIG. 10 illustrate the DRX operation of the mobile station and the base station for transmitting or not transmitting CSI/SRS depending on the evaluation result, as will be explained. Obviously, assuming the UE is in active time, the DRX inactivity timer is running and would expire in subframe N-2, assuming no PDCCH has been received prior to that. The PDCCH (whether uplink grant or reverse link assignment) is received in subframe N-3, and subframes N-10 and N are configured for periodic CSI/SRS transmission. Thus, the UE reports CSI/SRS in subframe N-10 (not considered for explanation) and now has to decide whether to report CSI/SRS in subframe N or not.

The UE as well as the eNodeB now determine whether the UE will transmit CSI/SRS as configured in subframe N or not. Thus, the determination is based on whether subframe N is determined to be active or inactive for the UE. Stated differently, information relating to the DRX status of a subframe available before and during subframe N-4 is taken into account for determination, while information available after after subframe N-4 is discarded for determination (but still, processed in accordance with other processes).

Therefore, in FIG. 9 The PDCCH is received in subframe N-3, i.e., after subframe N-4, and thus discarded to determine whether or not the UE will transmit CSI/SRS in subframe N. On the other hand, the PDCCH of subframe N -3 is taken into account essentially to restart the DRX inactivity timer in accordance with the normal behavior of the UE, thus resulting in a case where the UE remains in active time.

However, in order to determine whether or not to transmit CSI/SRS, the UE and the eNodeB determine that the UE would be idle in subframe N (as opposed to the actual situation), for the following reason: before and during subframe N-4, no PDCCH has not been adopted to restart the DRX sleep timer, so the UE and the eNodeB determine, based on the current value of the DRX sleep timer in subframe N-4, that the DRX sleep timer will indeed expire in subframe N-2. Due to the allowable expiration of the DRX inactivity timer, the UE and the eNodeB determine that the UE will be in idle time in subframe N (which is not fair due to the unaccounted for PDCCH in subframe N-3), and the UE will therefore not transmit CSI /SRS, as opposed to configuration (see FIG. 9 "no UL transmission"). The eNodeB will not expect any CSI/SRS transmission from the UE and thus will not even attempt to receive the CSI/SRS.

The exemplary scenario of FIG. 10 is almost similar to the scenario shown in FIG. 9, with the significant exception that the PDCCH is received in subframe N-4 instead of subframe N-3. Therefore, the determination of whether or not to transmit the CSI/SRS in the configured subframe N in this case also considers the PDCCH in the N-4 subframe. The DRX sleep timer is restarted in subframe N-4 due to the received PDCCH. The estimation process evaluates the UE's DRX status for subframe N as active time (assuming the DRS inactivity timer does not expire in subframe N), which means that the UE will report the CSI/SRS as configured. The eNodeB comes to the same conclusion based on the same information and thus waits for a CSI/SRS message from the UE. No double decoding at the eNodeB is needed anymore since the eNB and UE arrive at the same unambiguous evaluation result.

In FIG. 11 shows another DRX scenario based on which the above-described first embodiment will be further explained. The UE is assumed to be in a DRX mode, in particular a short DRX cycle where periods of on duration (active time) alternate with DRX opportunities (inactive periods). In this example, the duration of the on state is taken as the duration of three subframes, where the short DRX cycle is equal to the duration of 7 subframes, the inactive time is thus equal to 4 subframes. Again, subframes N-10 and N are counted as configured for periodic CSI/SRS reporting. The on duration timer is executed in the mobile station.

Since the above-explained embodiment also takes into account the DRX-related timers, in the UE, the UE and the eNodeB can estimate in subframe N-4, considering grants/assignments received before and during subframe N-4, that the UE will be in active time in subframe N, i.e., the on duration timer is executed. Considering the DRX short cycle timer and the on-duration timer for estimation, the UE as well as the eNodeB can accurately estimate when the UE will be in active time and inactive time. Again, the UE and the eNodeB only consider UL grants/DL assignments received before and during subframe N-4, which however in this case means that no PDCCHs are counted since no PDCCHs have been received recently. This primarily means that the UE still remains in the DRX mode, alternating active times with inactive times. Considering only UL grants/DL assignments, the UE/eNodeB would not judge that the UE is in idle time in subframe N since no PDCCH was received in time (before and during subframe N-4) to "wake up" the UE . However, with the additional consideration of DRX-related timers in subframe N-4 (in particular, the values of the DRX short cycle timer and the on duration timer), it is predictable that the UE will be active in subframe N, and thus will report CSI/SRS. Both the UE and the eNodeB arrive at the same determination result, and thus the UE transmits the CSI and SRS message and the eNodeB waits for the CSI/SRS without the need for double decoding.

Such a DRX scenario is explained in connection with FIG. 12, where, however, the on state duration is only 2 subframes long and the DRX capability is 5 subframes long. As is evident from FIG. 12, in N-2 and N-1 subframes, the UE would be in the on-duration active time. In subframe N-2, it is assumed that the UE receives a PDCCH (be it a UL grant or a DL assignment). In either case, the UE ideally wakes up with respect to receiving the PDCCH, ie, with respect to subframe N-1, and starts the DRX inactivity timer in subframe N-2. The UE is thus in active time in subframe N (assuming the inactivity timer does not expire before subframe N) and needs to report CSI/SRS as configured. This case is one example where the DRX message would be in the transition phase after receiving the PDCCH, where the eNodeB is required to perform dual decoding to determine whether CSI/SRS is actually being transmitted or not.

However, according to the present embodiment, predictable behavior of the UE can be achieved that eliminates the need for double decoding in the eNodeB. According to the present embodiment, only UL grants and DL assignments that are received before and during N-4 subframe are considered to determine whether or not to transmit periodic CSI/SRS as configured. The PDCCH is received in subframe N-2 and thus discarded to judge that, in combination with the values/status of the timer associated with DRX, results in the judgment that the UE is in idle time in subframe N, and thus the UE will not send CSI/SRS to the eNodeB. Thus, the UE does not transmit CSI/SRS despite being in active time in subframe N due to the received PDCCH in subframe N-2.

Therefore, additional consideration of DRX-related timers is advantageous and, depending on the circumstance, may result in a different evaluation result than not considering DRX-related timers. While only some of the DRX-related timers have been considered for the scenarios explained above, an embodiment of the invention allows for any or any combination of DRX-related timers to be considered, also depending on which timers are currently running, such as DRX retransmission timer or DRX long cycle timer. Thus, the embodiment of the invention will not be limited to the exemplary scenarios explained above.

The reason why the on-duration timer is invoked to determine whether to transmit CSI/SRS or not is that the mobile station can know in advance when the on-duration timer is executed based on the formula given in section 5.7 of TS36.321 .

- if short DRX cycle is used and [(SFN*10)+subframe number] modulo (DRX short cycle)=(drx start offset) modulo (DRX short cycle); or

- if long DRX cycle is used and [(SFN*10)+subframe number] modulo(DRX long cycle)=(drx start offset) modulo(DRX short cycle)=drx start offset:

- start the timer for the duration of the on state.

As can be seen from the formula, the subframes where the on-duration timer is executed can be uniquely determined by the mobile station and the eNodeB for different DRX cycles. However, whether a short DRX cycle or a long DRX cycle is used in a given subframe depends on other factors such as the DRX sleep timer status and thus the PDCCH reception status. Therefore, according to the above embodiment, the UE will consider grants/assignments received before and during subframe N-4 to determine whether the on-duration timer is running in subframe N, or in other words, the UE will consider assignments/grants received only before and during subframe N-4 in order to determine whether a short DRX cycle or a long DRX cycle is used in subframe N, and hence whether the on-duration timer is executed or not.

In a similar manner, the DRX retransmission timer may be taken into account to determine whether to transmit the CSI/SRS information in a given subframe. Since the UE starts a retransmission timer for the case where the transport block or PDSCH could not be correctly decoded in order to monitor the PDCCH for additional transport block retransmissions, the UE already knows some subframes in advance whether the DRX retransmission timer will be executed at a given subframe. For example, when the UE is to determine whether to transmit periodic CSI/SRS in subframe N, the UE already knows in subframe N-4 whether the DRX retransmission timer will be executed in subframe N because the HARQ feedback for a potential PDSCH transmission that could would have triggered the DRX retransmission timer in subframe N would have been transmitted in subframe N-4. For example, in the case where PDSCH transmission was scheduled in subframe N-8 with a PDCCH that could be correctly decoded, the UE will transmit NACK in subframe N-4. Therefore, the UE as well as the eNB know that the UE will start the DRX retransmission timer in subframe N in order to monitor for potential retransmissions.

The above described embodiment has been explained and illustrated in the figures as if no processing time would be necessary for the UE and the eNodeB, for example, to judge whether or not to transmit CSI/SRS in subframe N, or to process incoming PDCCHs. Thus, the above-described embodiment has been explained as if the processing took place "in subframe N-4". However, it will take more time for the UE and the eNodeB to decode the PDCCH, process the PDCCH transport block, evaluate the DRX status of subframe N, and of course also prepare the CSI/SRS. Processing may begin at subframe N-4 and may safely continue for another or two subframes. The more important part is that although the estimation may actually take place in, for example, subframe N-3 (eg, due to processing delay), only information (eg, PDCCH, DRX timer values/status) before and during subframe N-4. Therefore, the time between subframe N-4 and subframe N can be considered as a time budget for the UE, used for, among other things: PDCCH decoding, PDSCH transport block processing, estimation according to an embodiment, CSI/SRS preparation (if the transmission is to be completed). This applies in a similar manner to the rest of the embodiments explained below.

As explained above, the processing according to the first embodiment of the invention (applies similarly also to the rest of the embodiments explained below) may only need to be performed four subframes before the subframe configured for CSI and/or SRS, i.e., in subframe N -4 for configured subframe N. However, from an implementation point of view, the UE and the eNodeB may also perform estimation in each subframe N, whether or not periodic CSI and/or periodic SRS are configured even for subframe N+4.

While this may result in substantially more processing, the complexity of the UE and the eNodeB may be reduced.

The following illustrative text, reflecting the first embodiment of the invention explained above, is proposed as being implemented in the 3GPP TS 36.321 specification in section 5.7.

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- if the PDCCH indicates a new transmission (DL or UL):

- start or restart the drx inactivity timer.

- in the current subframe n, if the UE were not active according to the grants/assignments received before and during subframe n-4, and the on-duration timer and the drx retransmission timer would not be executed according to the grants/assignments received before and during subframe n-4, SRS initiated by type 0 [2] will not be reported.

- if CQI masking (cqi-Masc) is set by upper levels:

- in the current subframe n, if the on-duration timer would not be executed in accordance with the grants/assignments received before and during subframe n-4, no CQI/PMI/RI/PTI on the PUCCH would be reported.

- otherwise:

- in the current subframe n, if the UE were not active according to the grants/assignments received before and during subframe n-4, and the on-duration timer and the drx retransmission timer would not be executed according to the grants/assignments received before and during subframe n-4, CQI/PMI/RI/PTI on the PUCCH will not be reported.

- Whether the UE monitors the PDCCH or not, the UE receives and transmits HARQ feedback and transmits a Type 1 [2] triggered SRS when expected.

Note: The same active time applies to all activated serving cells.

Second Embodiment

The second embodiment addresses the problem that some unpredictable UE behavior remains for the case of DRX MAC controls received by the UE from the eNodeB instructing the UE to enter DRX, i.e., enter DRX mode and thus become inactive. In other words, the eNodeB does not know which transmission format will be used by the UE in a subframe, depending on whether CSI/SRS is transmitted or not (eg, format 1a vs. format 2a, see table for PUCCH format in the background section). This problem will be explained in more detail in connection with FIG. 13 and FIG. 14 illustrating DRX diagrams where processing is performed according to the first embodiment.

It is assumed that N-10 and N subframes are configured for periodic CSI/SRS transmission. A PDCCH with a downlink resource assignment for a DRX MAC CE on the PDSCH is received in subframe N-4 as well as a DRX MAC CE over the PDSCH. The DRX MAC CE is a command from the eNodeB for the UE to enter the DRX mode, ie start, for example, a short DRX cycle (not shown). HARQ is applied to the PDSCH containing the DRX MAC CE, because of this reason, the UE will send HARQ feedback (ACK/NACK) to the eNodeB in subframe N.

However, the eNodeB does not know whether the MAC CE UE correctly received the DRX transmitted in subframe N-4 without decoding the HARQ feedback (ACK/NACK) in subframe N. The estimation of the DRX status for the UE in subframe N depends on whether the UE received CE MAC is correct or not. In the case where the DRX MAC CE is received correctly in subframe N-4, the UE enters sleep time relative to subframe N-3 (ideally) and thus transmits an ACK without a CSI message and no SRS transmission in subframe N (see FIG. 13).

Otherwise, the UE fails to correctly decode the DRX MAC CE, so it stays active and transmits NACK and CSI/SRS in subframe N (see FIG. 14). Thus, the eNodeB still needs to perform double decoding to cover the above cases, which increases the complexity of the eNodeB. The corresponding DRX MAC CE retransmission is performed in the earliest 8 subframes after the initial transmission (according to the configuration), and in the exemplary configuration of FIG. 14 is allowed as 9 subframes after the initial transmission in subframe N+5. It is assumed that the DRX MAC CE is decoded correctly at this time, and thus the UE enters DRX, idle time.

According to the second embodiment, the judgment of whether or not to transmit the periodic CSI/SRS as configured takes into account only the DRX MAC CEs received before and during the N-(4+k) subframe, where k is an integer from 1 to K , and subframe N is a subframe configured for periodic CSI and/or SRS. This ensures that the eNodeB already knows in subframe N whether the MAC CE has been correctly received by the UE or not. It may thus already know the transmission format used in subframe N.

Based on this estimate, the transmission of the periodic CSI and/or SRS is controlled such that in the case where it is estimated that the UE will be in active time in subframe N, the CSI/SRS is transmitted, and in the case where it is estimated that the UE will not be in idle time in subframe N, CSI/SRS is not transmitted. Based on the scenario of Fig. 13 and FIG. 14, the result of applying the second embodiment of the invention is illustrated in FIG. 15 and FIG. 16.

For the exemplary embodiment of FIG. 15 and FIG. 16, k=1 is allowed, so that only DRX MAC CEs received by the UE before and during subframe N-5 should be taken into account to determine whether or not to transmit CSI/SRS as configured in subframe N. Thus, as evident from fig. 15, the DRX MAC CE received in subframe N-4 is not taken into account for the estimation process, due to this reason CSI/SRS is transmitted in subframe N along with HARQ feedback (in the example of FIG. 15, ACK). An eNodeB making the same determination and arriving at the same result waits for CSI/SRS transmission and HARQ feedback for DRX MAC CE. No double decoding is needed. (ACK/NACK can be decoded without double decoding).

The exemplary scenario of FIG. 16 assumes that the DRX MAC CE (and corresponding PDCCH) is received in subframe N-5, instead of subframe N-4. It is further assumed that the DRX MAC CE was correctly decoded by the UE, which thus exists in active time and enters DRX inactive time with respect to sub-dar N-4. According to the HARQ processing, the ACK is transmitted from the UE to the eNodeB four subframes after the DRX MAC CE, i.e., in the N-1 subframe. Thus, the eNodeB receives the HARQ feedback (eg, ACK) and can infer whether the MAC DRX CE was correctly decoded and applied by the UE. Therefore, the UE estimates that it will be idle in subframe N based on the correct reception of the DRX MAC CE and thus does not transmit the periodic CSI/SRS. The eNodeB receiving the ACK as HARQ feedback also determines that the UE will be idle in a subframe and thus does not expect any CSI/SRS reception.

Although the above explanation has focused on k=1, i.e., considering the DRX MAC CEs received before and during the N-5 subframe, k can also take on other values such as 2, 3, 4, etc. d. The use of large values of k increases the internal processing time available for the eNB to process the received HARQ feedback for the MAC CE and to decide on the expected PUCCH format to properly detect and decode the PUCCH in subframe N.

Although the above embodiment has been described so far as an independent embodiment, being an alternative to the first embodiment, the second embodiment and the first embodiment can be successfully combined. Thus, the UE judges the DRX status itself for subframe N, and thus also whether or not to transmit periodic CSI/SRS in subframe N, based on:

- UL grants and/or DL assignments received before and during subframe N-4, as well as based on DRX-related timers in subframe N-4 (as described for the first embodiment), and

- DRX MAC CEs received by the UE before and during the N-(4+k) subframe (according to the second embodiment).

Therefore, different subframe periods are used to account for grants/assignments and timer associated with DRX and to account for DRX MAC CE.

However, alternatively, instead of also considering the DRX-related timers as explained in connection with the first embodiment, the UE may judge the DRX status by itself in subframe N and thus also whether or not to transmit a periodic CSI/SRS in subframe N, based on:

- UL grants and/or DL assignments received before and during N-4 subframe, and

- DRX MAC CEs received by the UE before and during the N-(4+k) subframe (according to the second embodiment).

As explained above for the first embodiment, the processing according to the second embodiment of the invention may only be required to be performed five (or N-(4+k)) subframes before the subframe configured for CSI and/or SRS, i.e., in subframe N-4 for the configured subframe N. However, from an implementation point of view, the UE and the eNodeB may also perform estimation in each subframe N, whether or not periodic CSI and/or periodic SRS are configured even for subframe N+(4+ k). Although this may result in significantly more processing, the complexity of the UE and the eNodeB may be reduced.

The following illustrative text, reflecting the second embodiment of the invention explained above, is proposed as being implemented in the 3GPP TS 36.321 specification in section 5.7.

- if the PDCCH indicates a new transmission (DL or UL):

- start or restart the drx inactivity timer.

- in the current subframe n if the UE would not be in active time according to grants/assignments received before and during subframe n-4 and MAC control elements received before and during subframe n-(4+k), An SRS initiated by type 0 [2] will not be reported.

- if CQI masking (cqi-Masc) is set by upper levels:

- in the current subframe n, if the on-duration timer would not be executed in accordance with the grants/assignments received before and during subframe n-4, no CQI/PMI/RI/PTI on the PUCCH would be reported.

- otherwise:

- in the current subframe n if the UE would not be in active time according to grants/assignments received before and during subframe n-4 and MAC control elements received before and during subframe n-(4+k), CQI/PMI/RI/PTI will not be reported on PUCCH.

- Whether the UE monitors the PDCCH or not, the UE receives and transmits HARQ feedback and transmits a Type 1 [2] triggered SRS when expected.

Note: The same active time applies to all activated serving cells.

Third Embodiment

In contrast to the second embodiment, in which different time periods (N-(4+k) vs. N-4) were taken into account for different kinds of information used to determine whether or not to transmit CSI/SRS in subframe N, in in the present third embodiment, the same time period (N-(4+k)) is allowed for all kinds of information, as will be explained later.

According to one embodiment of the previous second embodiment, DRX MAC control elements that are received before and during N-(4+k) subframe are considered for estimation as well as granting UL/DL assignments received before and during N- subframe. 4, in a further alternative, DRX-related timers may be further considered for estimation to improve estimation. Thus, information of different periods of subframes is used.

According to the third embodiment, information as available in the N-(4+k) subframe is constantly used for evaluation according to any of the above-described embodiments of the second embodiment. Therefore, the present third embodiment is closely related to any of the embodiments of the second embodiment, except for changing the allowable time periods of the information taken into account for evaluation.

Specifically, the UE and the eNodeB determine whether the UE is in active time for subframe N, and thus whether it will transmit periodic CSI/SRS as configured in subframe N, based on the UL grants/DL assignments received UE before and during the N-(4+k) subframe, where k is a positive integer from 1 to K. In the same way, and as already explained earlier, the DRX MAC CEs received by the UE before and during the N-(4) subframe +k) are also taken into account for the determination. In the case that DRX-related timers are also further considered for estimation, the status of DRX-related timers, such as the DRX-on-duration timer and the DRX-retransmission timer, for subframe N estimated in subframe N-(4+k) , i.e., grants/assignments received before and during subframe N-(4+k) should be counted and not in subframe N-4 as before.

By using the same N-(4+k) timing consideration, the implementation of the invention in the UE and the eNodeB is simplified.

The following illustrative text, reflecting the third embodiment of the invention explained above, is proposed as being implemented in the 3GPP TS 36.321 specification in section 5.7.

- if the PDCCH indicates a new transmission (DL or UL):

- start or restart the drx inactivity timer.

- in the current subframe n, if the UE was not in active time according to the grants/assignments and MAC control elements received before and during subframe n-(4+k), SRS initiated by type 0 [2] would not be reported .

- if CQI masking (cqi-Masc) is set by upper levels:

- in the current subframe n, if the on-duration timer would not be executed in accordance with the grants/assignments received before and during subframe n-4, no CQI/PMI/RI/PTI on the PUCCH would be reported.

- otherwise:

- in the current subframe n, if the UE were not in active time according to the grants/assignments and MAC controls received before and during subframe n-(4+k), there would be no CQI/PMI/RI/PTI on the PUCCH communicate.

- Whether the UE monitors the PDCCH or not, the UE receives and transmits HARQ feedback and transmits a Type 1 [2] triggered SRS when expected.

Note: The same active time applies to all activated serving cells.

Fourth Embodiment

The fourth embodiment also deals with the problem caused by the reception of MAC DRX control elements, as already explained for the second embodiment (see above). However, instead of taking into account the DRX MAC CEs received by the UE before and during the N-(4+k) subframe, according to the second embodiment, only the DRX MAC CEs for which an acknowledgment (HARQ feedback) was transmitted from the UE are taken into account for estimation. in the eNodeB before and during the N-(3+k) subframe, k is a positive integer from 1 to K. The advantage is that both the eNodeB and the UE have the same understanding of what information is taken into account to determine whether whether or not to transmit periodic CSI/SRS in subframe N. The fourth embodiment will be explained in connection with FIG. 17 - fig. 19.

As is evident from FIG. 17, k=1 is allowed for the exemplary illustrations of FIG. 17-fig. 19 so that only DRX MAC CEs for which an ACK is sent back to the eNodeB before and during subframe N-4 are counted. In addition, it is assumed that the PDCCH indicating transmission for the DRX MAC CE on the PDSCH and the DRX MAC CE are received in the N-8 subframe. Provided that the UE successfully detects the PDSCH, based on the PDCCH, and decodes the DRX MAC CE instructing the UE to enter DRX (i.e., during idle time), the UE will (ideally) enter DRX mode and become dormant relatively subframe N-7. This is an ideal assumption, as explained earlier, in reality the UE will only know approximately in subframe N-5 that it has received the DRX MAC CE and may therefore transition to the DRX sleep time. In addition, the UE will send a HARQ feedback ACK in subframe N-4.

The UE determines whether or not to transmit the periodic CSI/SRS as configured for subframe N based on the acknowledgment for the DRX MAC CE transmitted in subframe N-4. Thus, the receipt of the MAC DRX CE is acknowledged in subframe N-4, i.e., the ACK is transmitted to the eNodeB and thus the UE determines that it will not transmit CSI/SRS as configured in subframe N, since it will be in idle time in subframe N. In a similar manner, the eNodeB waits for and receives the HARQ feedback ACK in subframe N-4, and thus determines that the UE will not transmit periodic CSI/SRS in subframe N. No double decoding is needed.

Fig. 18 is similar to the illustrative scenario in FIG. 17, with the difference that it is assumed that the DRX MAC CE was unsuccessfully decoded by the UE, which thus sends HARQ NACK feedback to the eNodeB in subframe N-4 and thus remains active. Since no acknowledgment was sent for the DRX MAC CE before and during subframe N-4, but instead, NACK, the UE determines that it will transmit periodic CSI/SRS in subframe N. The eNodeB comes to the same conclusion since it receives the NACK of the N-4 subframe, and thus knows that the UE could not decode and appropriately apply the DRX MAC CE.

As is evident from FIG. 18, the eNodeB, after receiving the NACK for the DRX MAC CE from the UE, transmits the DRX MAC CE 9 subframes later than the initial transmission. After transmission, it is assumed that the UE can correctly decode the DRX MAC CE and thus enter the DRX mode, in particular during idle time. The corresponding HARQ feedback ACK for the retransmitted DRX MAC CE is transmitted in subframe N+5.

Fig. 19 illustrates an exemplary scenario similar to that of FIG. 17 and FIG. 18, but with the significant difference that the DRX MAC CE is received in subframe N-7, not in subframe N-8. Thus, the HARQ feedback for receiving the MAC DRX CE is transmitted from the UE to the eNodeB four subframes after the reception, i.e., in the N-3 subframe, and thus outside the window determined to be taken into account for determining whether to transmit or non-periodic CSI/SRS in subframe N. Therefore, the DRX MAC CE received by the UE in subframe N-7 is discarded for determination, although it is, of course, properly handled by other functions of the UE. Therefore, in order to determine whether or not to transmit the periodic CSI/SRS in subframe N, it is redundant whether the DRX MAC CE is successfully decoded or not, only the DRX MAC CEs are considered in the mentioned relation for which ACK is transmitted before and during the subframe N-4, which is not true in the illustrative scenario of FIG. 19.

Thus, in the case where the UE can successfully process the DRX MAC CE, it will enter DRX, i.e., become inactive, but still must transmit the CSI/SRS in subframe N, even though it has not been would be in active time in subframe N according to DRX.

The following illustrative text, reflecting the fourth embodiment of the invention explained above, is proposed as being implemented in the 3GPP TS 36.321 specification in section 5.7.

- if the PDCCH indicates a new transmission (DL or UL):

- start or restart the drx inactivity timer.

- in the current subframe n if the UE would not be in active time according to grants/assignments received before and during subframe n-4 and according to MAC control elements for which HARQ feedback was transmitted before and during subframe n-(3+k), SRS initiated by type 0 [2] will not be reported.

- if CQI masking (cqi-Masc) is set by upper levels:

- in the current subframe n, if the on-duration timer would not be executed in accordance with the grants/assignments received before and during subframe n-4, no CQI/PMI/RI/PTI on the PUCCH would be reported.

- otherwise:

- in the current subframe n if the UE would not be in active time according to grants/assignments received before and during subframe n-4 and according to MAC control elements for which HARQ feedback was transmitted before and during subframe n-(3+k), the on-duration timer and the retransmission timer drx would not execute according to grants/assignments received before and during subframe n-(3+k), CQI/PMI/RI/PTI in PUCCH will not be reported.

- Whether the UE monitors the PDCCH or not, the UE receives and transmits HARQ feedback and transmits a Type 1 [2] triggered SRS when expected.

Note: The same active time applies to all activated serving cells.

Fifth Embodiment

The additional fifth embodiment is significantly different from the previous embodiments and mainly eliminates the CSI/SRS transmission uncertainty from the UE in the transition phases by considering the DRX status of the previous subframe N-k to determine whether or not to transmit periodic CSI/DRX in subframe N.

In more detail, the UE will transmit periodic CSI and/or SRS to the eNodeB as configured for subframe N, in case the UE is active in subframe N-k, where k is a positive integer from 1 to K. This fifth embodiment provides a simple behavior for the UE and the eNodeB, but still guaranteeing CSI/SRS transmission predictability to avoid double decoding at the eNodeB.

k=1 is allowed for illustration purposes. Thus, in order to decide whether or not to transmit the periodic CSI/SRS as configured for subframe N, the UE receives the DRX status (i.e., active time or inactive time) in subframe N-4 and allows to determine whether same as the DRX status of subframe N. Thus, based on the general rule that the periodic CSI/SRS should be transmitted by the UE only when the UE is in active time, the UE can thus determine whether or not to transmit the periodic CSI/ SRS in subframe N, based on the DRX status of subframe N-4.

Fig. 20 illustrates an exemplary scenario of FIG. 19 but with the fifth embodiment applied, instead of applying the fourth embodiment. Thus, it is assumed that the PDCCH and the DRX MAC CE indicated by the PDCCH are received in subframe N-7, that the UE correctly decodes the DRX MAC CE and thus (ideally) enters the DRX idle time relative to subframe N-6 . The ACK is transmitted as HARQ feedback for the DRX MAC CE in subframe N-3 at the eNodeB.

To determine whether to transmit periodic CSI/SRS or not in subframe N, the UE determines whether it is in active time in subframe N-4 or not. Because the UE is not in active time in subframe N-4, due to the correctly decoded DRX MAC CE received earlier, the UE will determine not to transmit CSI/SRS. The eNodeB makes a similar determination and results that the UE will not transmit CSI/SRS because the UE is idle in subframe N-4, which corresponds to the DRX status for transmitting CSI/SRS in subframe N.

Although not shown, when the DRX MAC CE is incorrectly decoded by the UE, which thus does not enter sleep time relative to subframe N-6 but remains active, the UE will be active time in subframe N-4 and thus thus, the CSI/SRS will be reported in subframe N as configured. Thus, the eNodeB arrives at the same determination result, and thus expects and receives the periodic CSI/SRS in subframe N.

The fifth embodiment reduces the implementation complexity for both the UE and the eNodeB while solving the problem of avoiding double decoding in the eNodeB.

Although the alternative approach is simpler in terms of implementation, it should be noted that, on the other hand, since only the DRX status of subframe N-k is taken into account for deciding whether to transmit CSI/SRS in subframe N or not, the usefulness of the information The CSI/SRS for scheduling could be reduced. The period of the CSI/SRS message is essentially shifted k frames from the active DRX time, i.e., the CSI/SRS message starts k subframes after the active DRX time starts and ends k subframes after the active time ends. DRX.

The following illustrative text, reflecting the fifth embodiment of the invention explained above, is proposed as being implemented in the 3GPP TS 36.321 specification in Section 5.7.

- if the PDCCH indicates a new transmission (DL or UL):

- start or restart the drx inactivity timer.

- in current subframe n, if the UE was not active in subframe n-4, SRS initiated by type 0 [2] will not be reported.

- if CQI masking (cqi-Masc) is set by upper levels:

- in the current subframe n, if the on-duration timer would not be executed in accordance with the grants/assignments received before and during subframe n-4, no CQI/PMI/RI/PTI on the PUCCH would be reported.

- otherwise:

- in the current subframe n, if the UE was not active in subframe n-4, no CQI/PMI/RI/PTI will be reported on the PUCCH.

- Whether the UE monitors the PDCCH or not, the UE receives and transmits HARQ feedback and transmits a Type 1 [2] triggered SRS when expected.

Note: The same active time applies to all activated serving cells.

Hardware and software implementation of the invention

Another embodiment of the invention relates to the implementation of the above-described various embodiments using hardware and software. In this regard, the invention provides a user equipment (mobile terminal) and an eNodeB (base station). User equipment is adapted to perform the methods described in this application.

Additionally, it should be understood that various embodiments of the invention may be implemented or performed using computing devices (processors). The computing device or processor may, for example, be general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, and so on. Various embodiments of the invention may also be carried out or carried out using a combination of these devices.

In addition, various embodiments of the invention may also be implemented via software modules that are executed by a processor, or directly in hardware. A combination of software modules and hardware implementation may also be possible. Software modules may be stored on any form of computer-readable storage media, such as RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROMs, DVDs, etc.

It should be further noted that the individual features of the various embodiments of the invention may be individually or in any combination the subject of the invention.

A person skilled in the art will understand that numerous changes and/or modifications can be made to the present invention depicted in particular embodiments without departing from the essence and scope of the invention, as the breadth of its description. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive.

Claims (24)

1. Base station, containing: a transmitter that, in operation, transmits to the mobile station configuration information for transmission in subframe N from the mobile station to the base station at least one of the channel quality information reports and the sounding reference signal, and transmits to the mobile station the access control control to medium (MAC) with respect to a discontinuous reception (DRX) operation, and a receiver that, in operation, does not receive the channel quality information report or sounding reference from the mobile station in subframe N if the mobile station is determined not to be in DRX active time in subframe N based on at least the MAC control element received by the mobile station before and during the N-(4+k) subframe, where k is an integer equal to or greater than 1. 2. The base station according to claim 1, wherein the channel quality information report and/or sounding reference signal is periodically transmitted from the mobile station. 3. The base station of claim 1, wherein the transmitter, in operation, transmits to the mobile station an assigned uplink resource for the uplink shared channel and/or an assignment of the downlink resource for the downlink shared channel, and the mobile station the station is determined not to be in DRX active time in subframe N based on the uplink resource grant and/or downlink resource assignment that is received by the mobile station before and during subframe N-(4+k). 4. The base station of claim 1, wherein the receiver, in operation, receives the channel quality information report and/or sounding reference from the mobile station in subframe N if the mobile station is determined to be in DRX active time in subframe N . 5. The base station of claim 1, wherein the mobile station is determined to be in DRX active time in subframe N based on DRX related timers running for the mobile station, including at least one of a DRX inactivity timer, DRX On Duration Timer; and DRX Retransmission Timer. 6. The base station of claim 1, wherein the transmitter, in operation, transmits radio resource control (RRC) signaling to the mobile station to limit the periodic transmission of the channel quality information report to only during active DRX time. 7. The base station of claim 1, wherein any MAC control element related to the DRX operation in N-(3+k) to N subframes should be ignored. 8. The base station of claim 1, wherein the integer value K is 1. 9. A configuration method performed by a base station, comprising the steps of: transmitting to the mobile station configuration information for transmission in subframe N from the mobile station to the base station at least one of the channel quality information reports and the sounding reference signal; transmitting to the mobile station a media access control (MAC) control regarding a discontinuous reception (DRX) operation, and do not receive the channel quality information report or sounding reference from the mobile station in subframe N if the mobile station is determined not to be in DRX active time in subframe N based on at least the MAC control received by the mobile station before and in subframe flow N-(4+k), where k is an integer equal to or greater than 1. 10. The method of claim 9, wherein the channel quality information report and/or sounding reference signal is periodically transmitted from the mobile station. 11. The method of claim 9, comprising the step of transmitting to the mobile station an allocated uplink resource for the uplink shared channel and/or an assignment of a downlink resource for the downlink shared channel, wherein the mobile station is determined not to be in DRX active time in subframe N based on on the granted uplink resource and/or the downlink resource assignment that are received by the mobile station before and during the N-(4+k) subframe. 12. The method of claim 9, comprising the step of receiving a channel quality information report and/or a sounding reference from the mobile station in subframe N if the mobile station is determined to be in DRX active time in subframe N. 13. The method of claim 9, wherein the mobile station is determined to be in DRX active time in subframe N based on DRX associated timers running for the mobile station, including at least one of a DRX inactivity timer, a timer the duration of the DRX on state and the DRX retransmission timer. 14. The method of claim 9, comprising the step of transmitting radio resource control (RRC) signaling to the mobile station to limit the periodic transmission of the channel quality information report only during the active DRX time. 15. The method of claim 9, wherein any MAC control relating to a DRX operation in N-(3+k) to N subframes should be ignored. 16. The method of claim 9, wherein the integer value of K is 1.

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