RU2763997C1 - Tdd dynamic uplink/downlink configuration using dci - Google Patents

Abstract

FIELD: wireless communication.

SUBSTANCE: invention relates to the field of wireless communication. An integrated circuit that, in operation, controls processing in a mobile station operating in one of a plurality of time division duplex (TDD) configurations in a communication system, the processing including the steps of: receiving a system information block (SIB) that includes including a default TDD configuration defining uplink, downlink and special subframes in one or more radio frames, receiving downlink control information and a corresponding error detection code for downlink control information, in response to successfully decoding the downlink control information with an error detection code, determine a TDD configuration from a plurality of TDD configurations based on the downlink control information, determine at least one serving cell to which said specific TDD configuration is to be applied applies said specific TDD configuration to one or more radio frames.

EFFECT: providing improved indication of the time division duplex communication configuration.

10 cl, 14 dwg, 4 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The invention relates to methods for specifying a time division duplex uplink/downlink configuration for a mobile station. The invention also provides a mobile station and a base station for participating in the methods described in the document.

BACKGROUND OF THE INVENTION

Long Term Communications Evolution (LTE)

Third generation (3G) mobile communication systems based on WCDMA (Wideband Code Division Multiple Access) radio access technology are being deployed on a large scale around the world. The first step in expanding or developing this technology involves the introduction of High Speed Downlink Packet Access (HSDPA) and enhanced uplink, also referred to as High Speed Uplink Packet Access (HSUPA), providing a radio access technology that is highly competitive.

To prepare for further growth in user demand and compete with new radio access technologies, the 3GPP consortium has proposed a new mobile communication system called Long Term Evolution (LTE). LTE is designed to meet the carrier needs for transporting high-speed data and multimedia, as well as supporting high-performance voice transmission, with a focus on the next decade. The ability to provide high bit rates is a key indicator for LTE.

The 3GPP Long Term Evolution (LTE) Work Item Specifications (WI) referred to as "UMTS Advanced Terrestrial Radio Access" (UTRA) and "UMTS Universal Terrestrial Radio Access Network" (UTRAN) have been finalized as Release 8 (LTE Rel.8). The LTE system introduces efficient packet 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 to enable flexible system deployment using a given spectrum. On the downlink, orthogonal frequency division multiplexing (OFDM) based radio access has been adopted due to its inherent immunity to multipath interference (MPI) due to low symbol rate, use of cyclic prefix (CP), and compatibility with various transmission band arrangements. Single carrier frequency division multiple access (SC-FDMA) radio access has been applied in the uplink because the provision of services for a large coverage area has been prioritized over increasing the peak bit rate given the limited transmission power of the user equipment (UE). Rel version. 8/9 LTE adopts many key packet radio access techniques including multiple input multiple output (MIMO) channel transmission techniques, and implements a highly efficient control signaling structure.

LTE architecture

The general architecture is shown in FIG. 1 and a more specific representation of the E-UTRAN architecture is given in FIG. 2. The E-UTRAN consists of an Evolved Node B (eNodeB) providing E-UTRAN User Plane (PDCP/RLC/MAC/PHY) and Control Plane (RRC) protocol terminations towards the User Equipment (UE). The eNodeB (eNB) provides the "host" for the Physical (PHY), Media Access (MAC), Radio Link Control (RLC), and Packet Data Control Protocol (PDCP) layers, which include header compression and user plane encryption functionality. . It also provides Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions, including radio resource management, admission control (to the network), scheduling, uplink consistent quality of service (QoS) enforcement, cell information broadcast, user and control plane data encryption/decryption, and header compression/decompression. downlink/uplink packets in the user plane. The eNodeBs are connected to each other via the X2 interface.

The eNodeBs are also connected via the S1 interface to the Evolved Packet Core (EPC), more specifically to the Mobility Management Module (MME) via the S1-MME and to the Serving Gateway (SGW) via the S1-U. The S1 interface maintains a many-to-many relationship between MMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user data packets, also acting as a mobility anchor for the user plane during handovers between eNodeBs and as a mobility anchor between LTE and other 3GPP technologies (terminating for the S4 interface and relaying traffic between 2G/3G systems and GW PDN) . For UEs in the dormant state, the SGW is the end of the downlink data path and initiates paging when downlink data arrives for the UE. It administers and stores user equipment contexts, such as IP data service parameter information, intranet routing. It also replicates user traffic in case of legitimate interception.

The MME is the key control node for the LTE access network. It is responsible for the tracking and paging procedure of the user equipment in the idle state, including retransmissions. It takes part in the data link activation/deactivation process and is also responsible for selecting the SGW for the user equipment at initial connection and during intra-LTE handover involving a core network node (CN) relocation. It is responsible for user authentication (by interacting with the Home Subscriber Server (HSS)). Non-Access Layer Signaling (NAS) terminates in MME and is also responsible for generating and allocating temporary identities for user equipment items. It checks the authorization of the user equipment for idle (call) connection to the Public Land Mobile Network (PLMN) and enforces the user equipment's roaming restrictions. The MME is a network endpoint for encryption/integrity protection for NAS signaling and manages security (system) keys. The MME also supports legitimate signaling interception. The MME also provides a function in the control plane for mobility between LTE and 2G/3G access networks with an S3 interface ending in MME from SGSN. The MME is also the end of the S6a interface towards the home HSS for roaming user equipments.

Component carrier structure in LTE (Version 8)

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

subcarriers, as also shown in FIG.

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

последовательных поднесущих в частотной области, как показано на Фиг.4 (например, 12 поднесущих для компонентной несущей). В LTE 3GPP (Версии 8), блок физических ресурсов, таким образом, состоит из

ресурсных элементов, соответствующих одному временному интервалу во временной области и 180 кГц в частотной области (для получения дополнительной информации относительно ресурсной сетки нисходящей линии связи, см., например, документ TS 36.211 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)", раздел 6.2, доступный по адресу http://www.3gpp.org и включенный в документ путем ссылки).Given a multi-carrier communication system, such as employing OFDM, such as used in the 3GPP Long Term Telecommunications Evolution (LTE), the smallest resource block that can be assigned by the scheduler is a single "resource block". The 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 shown in FIG. 4 (eg, 12 subcarriers for a component carrier). In 3GPP LTE (Release 8), a physical resource block thus consists of

resource elements corresponding to one time slot in the time domain and 180 kHz in the frequency domain (for more information on the downlink resource grid, see, for example, 3GPP TS 36.211, "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, распространяющихся по полному подкадру, именуются "парой ресурсных блоков", или эквивалентно "парой RB" или "парой PRB". One subframe consists of two slots, so there are 14 OFDM symbols per subframe when the so-called "normal" CP (cyclic prefix) is used, and 12 OFDM symbols per subframe when the so-called "extended" CP is used. For terminology, in the following time-frequency resources equivalent to those

consecutive subcarriers spreading over a full subframe are referred to as a "resource block pair", or equivalently a "RB pair" or "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 term replaces "cell", which refers to a combination of downlink and optionally uplink resources. The association between the carrier frequency for the downlink resources and the carrier frequency for the uplink resources is indicated in the system information transmitted on the downlink resources.

Similar assumptions for component carrier structure apply to later versions as well.

Logical and transport channels

The MAC layer provides 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 logical control channels. Dedicated Traffic Channel (DTCH) and Multicast Traffic Channel (MTCH) are traffic logical channels.

Data exchange from the MAC layer with the physical layer is carried out through transport channels. Data is multiplexed into transport channels depending on how it is transmitted over the air. The transport channels are classified as downlink or uplink channels 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 Link (UL-SCH) and Random Access Channel (RACH) are uplink transport channels.

Multiplexing is then performed between logical channels and transport channels on the downlink and uplink, respectively.

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

In order to inform scheduled users of their allocation status, transport format, and other data-related information (eg, HARQ information, transmission power control (TPC) 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 allocation to the user may vary from subframe to subframe. It should be noted that allocation to the user may also be performed on a TTI (Transmission Time Interval) basis, where the duration of the TTI may be a multiple of the number of subframes. The duration of the TTI may be fixed in the coverage area for all users, may be different for different users, or may even be dynamic for each user. Typically, L1/2 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 a message in the form of Downlink Control Information (DCI), which in most cases includes resource assignments and other control information for a mobile terminal or group of UEs. In general, multiple PDCCHs may be transmitted in one subframe.

It should be noted that in 3GPP LTE, assignments for uplink data transmissions, also referred to as scheduled uplink grants or uplink resource assignments, are also carried on the PDCCH.

In general, information sent with L1/L2 control signaling for uplink or downlink radio resource assignment (specifically in LTE(-A) Release 10) can be grouped into the following groups of units:

- Identification data (identifier) of the user, indicating the user that is distributed. They are usually included in the checksum by masking the CRC with the user's identity;

- Resource allocation information indicating the resources (resource blocks, RB) on which the user is allocated. It should be noted that the number of RBs a user is allocated to can be dynamic;

- The carrier indicator, which is used if the control channel transmitted on the first carrier assigns resources that are related to the second carrier, that is, resources on the second carrier or resources related to the second carrier;

- Modulation and coding scheme, which determines the applied modulation scheme and coding rate;

- HARQ information such as new data indicator (NDI) and/or redundancy version (RV), which is particularly useful in retransmissions of data packets or portions thereof;

- Power control commands for adjusting the transmission power for the intended transmission of data or control information in the uplink;

- Reference signal information such as applied cyclic shift and/or orthogonal coverage code index to be used for transmitting or receiving reference signals related to the assignment;

- An uplink or downlink assignment index that is used to identify the order of assignments, which is particularly useful in TDD systems;

- Frequency hopping information, eg whether and how to apply resource frequency hopping to improve frequency diversity;

- CSI request, which is used to initiate transmission of link state information in the assigned resource; and

- Multicluster information, which is a flag used to indicate and control whether the transmission occurs in one cluster (contiguous set of RBs) or in multiple clusters (at least two non-contiguous sets of contiguous RBs). Multi-cluster distribution was introduced according to LTE-(A) 3GPP Release 10.

It should be noted that the listing above is non-exhaustive and not all of the items of information mentioned need be present in every PDCCH transmission depending on the DCI format that is being used.

The downlink control information occurs in several formats that differ in overall size as well as the information contained in its fields. The various DCI formats currently defined for LTE are set forth below and detailed in 3GPP TS 36.212, Section 5.3.3.1 "Multiplexing and channel coding", (available at http://www.3gpp.org and included into the document by reference). For more information regarding DCI formats and specific information that is carried in DCI, please refer to the technical standard or the document LTE - The UMTS Long Term Evolution - From Theory to Practice, ed. Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 9.3 incorporated herein by reference.

Format 0: DCI format 0 is used to transmit resource grants for PUSCH using single-antenna port transmissions in uplink transmission mode 1 or 2.

Format 1: DCI Format 1 is used to carry resource assignments for PDSCH transmissions in one codeword (downlink transmission modes 1, 2 and 7).

Format 1A: The DCI format 1A is used for compact signaling of resource assignments for PDSCH transmissions in one codeword and for allocating a special preamble signature to the mobile terminal for contention-free random access.

Format 1B: DCI format 1B is used for compact signaling of resource assignments for PDSCH transmissions using closed loop precoding with rank-1 transmission (coding matrix) (downlink transmission mode 6). The transmitted information is the same as in Format 1A but with the addition of the precoding vector indicator used for PDSCH transmission.

Format 1C: DCI format 1C is used for ultra-compact transmission of PDSCH assignments. When the 1C format is used, PDSCH transmission is limited to using quadrature phase modulation (QPSK). This is used, for example, for paging signaling messages and system information broadcast messages.

1D Format: The 1D DCI format is used for compact signaling of resource assignments for PDSCH transmission using multi-user MIMO. The transmitted information is the same as in Format 1B, but instead of one of the precoding vector indicator bits, there is a single bit to indicate whether a power offset is applied to the data symbols. This function is required to show whether or not the transmit power is shared by two UEs. Future versions of LTE may expand this to a power sharing case with more UEs.

Format 2: DCI Format 2 is used to convey resource assignments for the PDSCH for the closed loop MIMO mode of operation.

Format 2A: DCI format 2A is used to convey resource assignments for the PDSCH for open-loop MIMO operation. The transmitted information is the same as for Format 2, except that if the eNodeB has two transmit antenna ports, then there is no precoding information, and for the four antenna ports, two bits are used to indicate the transmit rank.

Format 2B: Introduced in Release 9 and used to carry resource assignments for the PDSCH for bilayer beamforming.

Format 2C: Introduced in Release 10 and used to convey resource assignments for the PDSCH for single-user or multi-user closed loop MIMO operation using up to 8 layers.

2D Format: Introduced in Version 11 and used for broadcasts up to 8 levels; mainly used for COMP (Coordinated Multipoint).

Format 3 and 3A: DCI formats 3 and 3A are used to transmit power control commands for PUCCh and PUSCH with 2-bit or 1-bit power controls, respectively. These DCI formats contain separate power control commands for a group of UEs.

Format 4: DCI format 4 is used for PUSCH scheduling using spatial feedback multiplex transmissions in uplink transmission mode 2.

The following table gives an overview of some of the available DCI formats and typical bit counts, assuming for illustration purposes a system bandwidth of 50 RB and four antennas in the eNodeB. The number of bits listed in the right column includes the bits for the CRC for a particular DCI.

DCI format Purpose Number of bits including CRC 0 PUSCH grants 43 one PDSCH assignments in one codeword 47 1A PDSCH assignments using compact format 43 1B PDSCH Assignments - Rank -1 Transmission 46 PDSCH assignments using ultra-compact format 29 1D PDSCH assignments for multi-user MIMO 46 2 PDSCH Assignments for Closed Loop MIMO Operation 62 2A PDSCH Assignments for Open Loop MIMO Operation 58 2B PDSCH Assignments for Dual Layer Beamforming 57 PDSCH assignments for single-user or multi-user MIMO operation 58 2D PDSCH assignments for single-user or multi-user closed-loop MIMO, COMP 61 3 Transmit Power Control (TPC) Commands for Multiple Users for PUCCH and PUSCH with 2-bit Power Controls 43 3A Transmit Power Control (TPC) Commands for Multiple Users for PUCCH and PUSCH with 1-bit Power Controls 43 4 PUSCH grants 52

Fig. 5 illustrates the processing structure for one DCI according to Fig. 5.3.3.13 in GPP TS 36.212 as follows:

- Multiplexing of information elements (refers to the multiplexing of specific information elements that make up one DCI unit),

- Attaching CRC

- Channel coding

- Speed matching

In order for the UE to identify whether it received the PDCCH transmission correctly, error detection is provided by a 16-bit CRC attached to each PDCCH (ie, DCI). In addition, it is necessary for the UE to be able to identify which PDCCH instance(s) is intended for this. Theoretically, this can be done by adding an identifier to the PDCCH payload; however, it appears to be more efficient to scramble the CRC with the "UE Identity", which saves additional overhead. The CRC may be computed and scrambled as detailed by 3GPP in TS 36.212, section 5.3.3.2 "CRC attachment", hereby incorporated by reference. This section describes how error detection is provided on DCI transmissions through cyclic redundancy check (CRC). A brief description is given below.

The entire payload is used to calculate the CRC parity bits. The parity bits are calculated and attached. In the case where the UE transmit antenna selection is not configured or not applicable, after attachment, the CRC parity bits are scrambled with the corresponding radio network cell temporary identifier (RNTI).

The scrambling may further depend on the UE's transmit antenna selection, as is apparent from 36.212. In the case where the UE transmit antenna selection is configured and applicable, after attaching, the CRC parity bits are scrambled with the antenna selection mask and the corresponding RNTI. Since in both cases the RNTI is included in the scrambling operation, for simplicity and without loss of generality, the following description of the embodiments simply refers to the CRC being scrambled (and descrambled, if applicable) with the RNTI, which should therefore be understood to be irrelevant to, for example, the next element in the scrambling process. , such as an antenna selection mask.

Accordingly, the UE descrambles the CRC by applying the "UE Identity", and if no CRC error is detected, the UE determines that the PDCCH carries its control information intended for it. The terminology "masking" and "unmasking" is also used for the above-described process of scrambling a CRC with an identity.

The "UE Identity" mentioned above, with which the CRC for DCI can be scrambled, may also be SI-RNTI (Radio Network Temporary Identifier for System Information), which is not a "UE Identity" per se, but rather an identifier, associated with the type of information that is indicated and transmitted, in this case system information. The SI-RNTI is usually specified in the specification and thus is known a priori to all UEs.

There are different types of RNTIs that are used for different purposes. The following tables, which are taken from Chapter 7.1 of 3GPP Document 36.321, should give an overview of the various 16-bit RNTIs and their applications.

Value (hexadecimal)

n/a

,

semi-permanent scheduling, temporary

,

and

(see note)

,

semi-permanent scheduling, temporary

,

and

Reserved for future use

Usage transport channel Logical channel Paging and System Information Change Notification PCH PCCH Broadcasting system information DL-SCH BCCH MCCH System Information Change Notification n/a n/a Response to a random access request DL-SCH n/a Conflict resolution (when there is no valid C-RNTI available) DL-SCH CCCH Msg3 message UL-SCH CCCH, DCCH, DTCH Dynamically Scheduled Unicast UL-SCH DCCH, DTCH Dynamically Scheduled Unicast DL-SCH CCCH, DCCH, DTCH PDCCH Ordered Random Access Initiation n/a n/a Semi-persistently scheduled unicast (activation, reactivation and retransmission) DL-SCH, UL-SCH DCCH, DTCH Semi-persistently scheduled unicast (deactivation) n/a n/a Physical layer uplink power control n/a n/a Physical layer uplink power control n/a n/a

Physical Downlink Control Channel (PDCCH) and Physical Downlink Shared Channel (PDSCH)

The Physical Downlink Control Channel (PDCCH) carries, for example, scheduled resource allocations for data transmission in the downlink or uplink.

Each PDCCH is transmitted using one or more so-called Control Channel Elements (CCEs). Each CCE corresponds to a set of Resource Elements (REs). In 3GPP LTE, currently one CCE consists of 9 Resource Element Groups (REGs, where one REG consists of four successive REs (consecutive in the frequency domain) other than potential REs for reference signals. Resource elements occupied by reference symbols are not included in REG units, which means that the total number of REGs in a given OFDM symbol depends on whether the reference signals are present.

OFDM символах (обычно либо 1, 2, либо 3 символах OFDM, как указано посредством PCFICH (физический канал управления индикатора формата), в исключительных случаях либо 2, 3, либо 4 символах OFDM, как указывается посредством PCFICH) в подкадре, распространяющегося по всей ширине полосы пропускания системы; полоса пропускания системы обычно является эквивалентной диапазону ячейки или компонентной несущей. Диапазон, занятый первыми

OFDM символами во временной области и

поднесущими в частотной области, также именуется диапазоном PDCCH или диапазоном канала управления. Оставшиеся

символов OFDM во временной области на

поднесущих в частотной области именуются диапазоном PDSCH или диапазоном совместно-используемого канала (см. ниже).PDCCH for user equipment units is transmitted on the first

OFDM symbols (typically either 1, 2 or 3 OFDM symbols as indicated by PCFICH (Physical Format Indicator Control Channel), exceptionally either 2, 3 or 4 OFDM symbols as indicated by PCFICH) per subframe, spreading over the entire system bandwidth; the system bandwidth is typically equivalent to the range of a cell or component carrier. Range occupied first

OFDM symbols in the time domain and

subcarriers in the frequency domain, also referred to as a PDCCH band or a control channel band. The remaining

OFDM symbols in the time domain on

subcarriers in the frequency domain are referred to as the PDSCH band or the shared channel band (see below).

To provide a downlink on a physical downlink shared channel (PDSCH), the PDCCH assigns a PDSCH resource for data (user) within the same subframe. The PDCCH control channel area in a subframe consists of a set of CCEs, where the total number of CCEs in the subframe control area are distributed over the entire time and frequency control resource. Multiple CCEs can be combined to effectively reduce the coding rate of the control channel. The CCE units are combined in a predetermined manner using a tree structure to achieve a different coding rate.

In LTE 3GPP PDCCH may aggregate 1, 2, 4 or 8 CCEs. The number of CCEs available for a control channel assignment is a function of several factors including carrier bandwidth, number of transmit antennas, number of OFDM symbols used for control, and CCE size, and so on. Multiple PDCCHs may be transmitted in a subframe.

At the transport channel layer, the information transmitted over the PDCCH is also referred to as L1/L2 control signaling. L1/L2 control signaling is transmitted on the downlink for each user equipment unit (UE). The control signaling is typically multiplexed with downlink (user) data in a subframe (assuming the allocation to the user may vary from subframe to subframe).

Time Division Duplex - TDD

LTE can operate in Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes in a consistent infrastructure designed to also support the evolution of TD-SCDMA (Synchronous Time Division Multiple Access). TDD separates the uplink and downlink transmissions in the time domain while the frequency may remain the same.

The term "duplex" refers to bi-directional communication between two devices, other than uni-directional communication. In the bidirectional case, transmissions over a communication channel in each direction may occur simultaneously ("full duplex") or in mutually exclusive time periods ("half duplex").

For TDD in the unpaired radio spectrum, the basic structure of RB and RE is depicted in Fig. 4, but only a subset of the radio frame's subframes are available for downlink transmissions; the remaining subframes are used for uplink transmissions, or for special subframes that contain a guard interval to allow switching between downlink and uplink transmission. The guard interval makes it possible to improve the timing of the uplink transmission. This TDD structure is known as "Frame Structure Type 2" in 3GPP LTE Release 8 and later, for which seven different configurations are defined allowing multiple downlink/uplink relationships and periodicity switching. 6 illustrates a Table with 7 different, indexed from 0 to 6, uplink/downlink configurations for TDD. As can be seen from it, the seven available downlink/uplink configurations for TDD can provide between 40% and 90% of the downlink subframes (assuming the special subframe is a downlink subframe, since part of such a subframe is available for downlink transmission).

7 shows frame structure type 2, specifically for a 5 ms switch point periodicity, ie, configurations 0, 1, 2 and 6 for TDD.

7 illustrates a radio frame having a duration of 10 ms and corresponding to two half-frames of 5 ms each. The radio frame consists of 10 subframes of 1 ms, where each of the subframes is assigned an "Uplink", "Downlink", or "Special" type, as defined by the table of FIG. 6, where "D" stands for "Downlink", "U" stands for "Uplink" and "S" stands for "Special".

As can be appreciated from FIG. 6, subframe #1 is always a Special subframe, and subframe #6 is a Special subframe for configurations 0, 1, 2, and 6 in TDD; for configurations 3, 4 and 5 in TDD, subframe #6 is for Downlink. The special subframes include three fields: DwPTS (Downlink Pilot Time Slot), GP (Guard Time) and UpPTS (Uplink Pilot Time Slot). The following Table shows information about the special subframe and in specific lists - the duration of DwPTS (Downlink Pilot Time Slot), GP (Guard Period) and UpPTS (Uplink Pilot Time Slot) as a time multiple of the sampling time T _s = (1/30720) ms , as defined for 3GPP LTE Release 11.

Special subframe configuration Normal cyclic prefix in downlink Extended Downlink Cyclic Prefix DwPTS UpPTS DwPTS UpPTS Normal cyclic prefix in uplink Extended uplink cyclic prefix Normal cyclic prefix in uplink Extended uplink cyclic prefix 0 6592 T _s 2192 T _s 2560 T _s 7680 T _s 2192 T _s 2560 T _s one 19760 T _s 20480 T _s 2 21952 T _s 23040 T _s 3 24144 T _s 25600 T _s 4 26336 T _s 7680 T _s 4384 T _s 5120 T _s 5 6592 T _s 4384 T _s 5120 T _s 20480 T _s 6 19760 T _s 23040 T _s 7 21952 T _s 12800 T _s eight 24144 T _s - - - 9 13168 T _s - - -

The TDD configuration applied in the system affects many operations performed at the mobile station and the base station, such as measurements for radio resource management (RRM), measurements for channel state information (CSI), channel estimation, PDCCH and HARQ detection timing. .

Specifically, the UE reads the system information to know the TDD configuration in its current cell, that is, which subframe to monitor for measurement, for CSI measurement and reporting, for time domain filtering for channel estimation, for PDCCH detection, or for feedback on acknowledgment/non-acknowledgment (ACK/NACK) in UL/DL.

Drawback of the current UL/DL semi-static configuration scheme in TDD

Currently TDD LTE allows asymmetric UL-DL allocations by providing seven different semi-statically configurable uplink/downlink configurations. The current mechanism for adapting the allocation of UL-DL is based on a system information collection procedure or a system information change procedure, where the UL-DL configuration in TDD is indicated by a system information block (SIB), specifically the TDD-config configuration parameter in SIB1, (regarding the system information broadcasting details). For information, see 3GPP TS 25.331, "Radio Resource Control(RRC)", version 6.7.0, section 8.1.1, incorporated herein by reference; available at http://www.3gpp.org).

With the system information change procedure in Release 8, the supported time scale for UL/DL TDD reconfiguration is every 640 ms or more. When reusing ETWS (Earthquake and Tsunami Warning System), the supported time scale for UL-DL TDD reconfiguration is every 320ms or more depending on the configured "default" paging cycle.

The semi-static distribution of the UL/DL TDD configuration may or may not correspond to the instantaneous traffic situation. However, it will be useful to tailor the UL/DL TDD configuration to current traffic needs; for example, to dynamically create more "blank" uplink subframes to mitigate interference with transmission, for example, in the uplink or downlink of a neighbor cell. Accordingly, Version 12 is expected to approve a more dynamic UL/DL TDD reconfiguration.

The 3GPP consortium has announced a study objective in TR 36.828 v1 1.0.0 to investigate timelines for various types of UL/DL TDD configuration changes and their advantages and disadvantages. In general, the conclusion of the study task showed that faster UL/DL TDD reconfiguration timelines provide more benefits than slower UL/DL TDD reconfiguration timelines. In addition, the scope of required changes to the description varies depending on the supported reconfiguration timelines.

The research objective, however, also identified problems with live UEs (UEs only compatible with standards earlier than Version 12 that do not implement the dynamic TDD reconfiguration mechanism) arising from different TDD configurations for different UEs. In particular, it is believed that if the base station wishes to dynamically reconfigure the TDD configuration for the UEs in the cell, the dynamic TDD reconfiguration can only be correctly handled by new UEs; in the case that a non-existing SIB-based TDD configuration indication method is used, but a more dynamic indication method, the incumbent UEs will not apply TDD reconfiguration. Therefore, the operating UEs will still assume the presence of reference signals, eg, CRS (Common Reference Symbol) in the downlink subframes in the radio frame according to the default TDD configuration (ie, indicated by the SIB). In case the TDD dynamic configuration has an uplink subframe instead of a downlink subframe, the operating UE will thus erroneously believe that CRS must be present, which may lead to incorrect channel measurements and estimates.

The research objective also considered RRC, MAC, and PHY signaling as ways of more dynamic indication. UL/DL TDD reconfiguration by RRC signaling is on the order of 200 ms and requires a reconfiguration message per RRC connected user unless a broadcast or multicast method is specified. UL/DL TDD reconfiguration by MAC sub-layer Control Element (CE) signaling in the MAC header is on the order of several tens of ms. Using a Physical Layer construction, such as that provided by L1/L2 control signaling in DCI, a UL/DL TDD adaptation time scale of the order of 10 ms can be achieved.

In view of the results of the above study task, the UL/DL TDD reconfiguration should be performed as quickly as possible, thus allowing flexible adaptation of the UL/DL TDD configuration to traffic situations.

SUMMARY OF THE INVENTION

One object of the invention is to provide an improved Time Division Duplex configuration indication that solves the problems of the prior art as discussed above. Dynamic adaptation of the TDD configuration of one or more radio frames will preferably be possible.

The problem is solved according to the object of independent claims. Useful embodiments are the subject of the dependent claims.

According to various embodiments of the invention, a time division duplexing (TDD) configuration to be used for transmission between a mobile station and a base station is encoded by the base station into a DCI transmission to the mobile station. In this context, the term "DCI transmission" is to be understood as a complete transmission, which in this case means DCI and the corresponding error detection-enabled code (such as CRC). The invention provides various embodiments of how this can be achieved.

According to a first aspect of the invention, the TDD configuration is encoded into an error detection code computed for DCI; more specifically, the specific TDD configuration is implicitly encoded into error-detecting code. For each of the assigned TDD configurations, a different identifier value is set, and both the mobile stations and the base stations are aware of the predefined identifier values and the relationship with the possible TDD configurations. More specifically, in LTE communication systems, the identifier may be a temporary radio network identifier having a length of 16 bits, which is then scrambled with a 16-bit error detection code (CRC).

Accordingly, when the base station wishes to dynamically change the default TDD configuration to another target TDD configuration for a particular cell, it will generate a DCI, calculate an appropriate error detection code for the DCI, and then scramble the calculated CRC with the identifier associated with the target TDD configuration that the mobile station(s) in this cell shall use for the next radio frame(s).

DCI as such (i.e., not CRC) may be either in the DCI format already defined in the LTE standards, or equivalent to having the same size as an already defined DCI format, e.g. Format 1C, or may be corresponding to a "new" DCI format , which serves the purpose of being used in conjunction with dynamic TDD reconfiguration.

In case a DCI already defined in LTE is used (such as Format 1C), then the base station may set one or more parameters in the DCI (in the case of Format 1C, resource block assignment, for example) to an invalid value, so that the mobile station processing the DCI and the invalid parameter can easily determine that the received DCI is not a "traditional" Format 1C DCI assigning downlink resources, but rather is used to send a TDD configuration for dynamic TDD reconfiguration.

The first aspect can be further improved in that the above invalid parameter of a given DCI Format (eg, DCI Format 1C) can be used to encode an additional parameter, as will be explained. It is allowed that an invalid parameter can take not only one invalid value, but various invalid values. In said case, an invalid parameter may be used to encode an indication that the DCI (with said invalid parameter) carries a TDD dynamic reconfiguration, as well as to encode an additional parameter (value). Specifically, the fact that the parameter is set to any invalid value or group thereof allows the mobile station to determine that the DCI will be a DCI carrying a TDD configuration indicator rather than a traditional DCI. Then, each (or group) of invalid values of said parameter can then be associated with a different value of another particular parameter. For example, the actually available invalid values can be associated with other TDD configurations such that the invalid parameter, and specifically one of the invalid parameter values, also indicates the index of the desired TDD configuration for dynamic UL/DL TDD reconfiguration.

In addition, the DCI Format already defined in 3GPP can be reused, namely by assuming the same bit size as that of the already defined DCI, but specifying different content (information elements) within the DCI for specific situations. For example, DCI Format 1C in 3GGP TS 36.212 can be extended so that for one set of cases, DCI Format 1C is used as already specified by 3GPP (for PDSCH assignments), but for the remaining (other) cases, DCI Format 1C is not the same as means 3GPP at present (as defined at the time of filing, respectively), and is intended for dynamic reconfiguration of TDD according to the invention.

As a third alternative, a new DCI Format may be specified, possibly a different length than existing DCI formats; the length depends on the additional content (parameters) to be included in said new DCI format. As will be explained in more detail below, in any case ("preset", "preset-extended", and "new" DCI), the DCI may include at least one additional parameter that may be used advantageously in conjunction with dynamic reconfiguration. TDD.

According to the above, the mobile station receiving the DCI and the corresponding error detection code will attempt to descramble and perform error checking on the error detection code using different identifiers predefined for different TDD configurations. When the mobile station successfully performs error checking with one of the various candidate identifiers, the mobile station will then determine the specific TDD configuration associated with that identifier for which the error checking was successful. The mobile station then knows the TDD configuration to apply for the next radio frame(s) in its cell.

In addition, the mobile station may determine the above additional parameter(s) to obtain additional benefits; details are provided in the detailed description section.

According to the second aspect of the invention, instead of implicitly encoding the TDD configuration into an error detection code as in the first aspect, the TDD configuration is directly encoded as a parameter in the DCI. Accordingly, the DCI generated by the base station contains a field (preferably up to 3 bits long) indicating the TDD configuration to be applied instead of the default TDD configuration. The second aspect of the invention further describes that the error detection code calculated for the DCI and transmitted along with the DCI from the base station to the mobile station is scrambled with a cell ID, which allows the mobile station to identify the target cell to which the TDD configuration should be applied.

The mobile station, upon receiving the DCI and the scrambled error detection code from the base station, first performs an error check on the error detection code and the DCI, which includes the step of descrambling the error detection code. The mobile station performs error checking until it determines the cell ID actually used for the base station's error detection code scrambling process.

From the determined cell ID, the mobile station first learns that the DCI is a DCI intended to transport a TDD configuration (rather than any other kind of DCI); secondly, the mobile station knows for which target cell (identified by the cell ID) the TDD configuration (included in the DCI) is actually intended to be applied. From the DCI payload, the mobile station learns the TDD configuration.

Naturally, the mobile station applies a certain TDD configuration only if it belongs to a certain target cell identified by the cell ID used to scramble the error detection code for DCI.

The second aspect can be used predominantly for a scenario in which there is one macro cell and various small cells; for example, the macro cell is operated with frequency division duplex, and the small cells are operated with time division duplex. The mobile station resides in the macro cell as well as the small cell. It is believed that the DCI (and error correction code) is transmitted from the base station of the macro cell, but for the purpose of dynamically reconfiguring the TDD of one (or more) small cells.

To this end, the cell ID used to scramble the DCI error detection code can identify only one of the cells for which the new TDD configuration is to be applied. Alternatively, different small cells can be grouped together and associated with a single cell (group) identifier such that by receiving a DCI and an error detection code scrambled with said single cell (group) identifier, mobile stations can determine for which cell(s) a new TDD configuration should apply and for which it shouldn't.

Although, as explained above, using such a cell ID to scramble the error detection code already allows the mobile station to identify the DCI that will carry the TDD configuration, the DCI may further contain an invalid parameter to reduce the risk of a false alarm. Specifically, when a base station generates a DCI to dynamically change the TDD configuration of one (or more) cells, the TDD configuration parameter is turned on, and the DCI parameter is also set to an invalid value. Which specific parameters should be set to invalid is less important, as long as the mobile station can identify said invalid parameter and thereby infer from this that the DCI is not a "traditional" DCI, but some carrying TDD configuration. Accordingly, the mobile station can infer from both the cell ID used in connection with the error detection code and the invalid DCI parameter that the DCI should additionally contain an indication of the new TDD configuration to be applied.

One example of an invalid parameter is the resource block assignment parameter in DCI Format 1C as defined by 3GPP. The resource block assignment parameter is set to an invalid value, eg all "1s".

As already explained in connection with the first aspect of the invention, the above invalid parameter can also be used to encode additional information; for example, an additional parameter value. If a plurality of invalid values are available for an invalid parameter, then all invalid values are associated with the information that the DCI carrying said invalid parameter is a DCI carrying one of the plurality of TDD configurations. On the other hand, each (or group) of invalid values is associated with a different value of another parameter. Thus, additional information can be transported to the mobile station without using additional bits. For example, the actual TDD configuration may be encoded into an invalid parameter; at least seven different invalid parameter values must be available to distinguish between the seven TDD configurations. Then, based on the specific invalid parameter value used in the DCI, the mobile station can determine the specific TDD configuration.

Instead of adopting a known DCI Format (such as DCI Format 1C defined by 3GPP), it is also possible to define a new DCI Format definition solely for the purpose of transporting the TDD dynamic reconfiguration indication, and possibly additional additional parameters, as will be discussed in more detail below.

According to the third aspect of the invention, the TDD configuration is directly encoded in the DCI, similar to the second aspect of the invention. The DCI further contains an invalid parameter that allows the mobile station to detect that the received DCI carries a TDD configuration indicator. Accordingly, if the mobile station determines that the DCI contains said specific invalid parameter, it proceeds to determine the specific TDD configuration contained in the DCI.

With respect to the third aspect of the invention, it is believed that any of the various well-known DCI Formats defined by the 3GPP may be used, such as the 1C DCI Format already discussed for the first and second aspects of the invention. However, other formats may be used instead.

The 1C DCI format as defined by 3GPP traditionally includes a Resource Block Assignment (RBA) parameter for PDSCH assignment. For the purposes of the third aspect, said RBA parameter may be set to an invalid value.

As with the previous aspects, additional information may be encoded into said invalid parameter if there are a number of invalid values for the invalid parameter. While any of the invalid values indicates that DCI (carrying said invalid parameter) is being used for the purpose of transporting the TDD configuration, each (or group) of invalid values is associated with additional information. For example, the actual TDD configuration may be encoded into an invalid parameter; at least seven different invalid parameter values must be available to distinguish between the seven TDD configurations. Then, based on the specific invalid parameter value used in the DCI, the mobile station can determine the specific TDD configuration.

A further improvement of the third aspect allows the error detection code for DCI to be scrambled with a so-called system information identifier (SI-RNTI in 3GPP). SI-RNTI is commonly used in 3GPP systems to transport system information, and different SI windows are defined so that the mobile station can determine which system information message can be indicated in which SI window (compare 3GPP TS 36.331, sections 5.2.1.2 and 5.2.3 ). According to 3GPP, only one SI message can be sent per SI window, but multiple times in that SI window (if necessary). Since different SI messages may be configured with different periodicities, it is possible that some SI windows are not used for any SI message; in other words, the mobile station is aware that in such unused SI windows, any transmission of the SI message will not be performed by the base station. This knowledge of the mobile station is used to its advantage either by transmitting the DCI transporting the TDD configuration in such an unused SI window, although the CRC for the DCI is scrambled with the SI-RNTI. Reception within the unused SI window allows the mobile station, in combination with the invalid parameter, to determine with higher certainty that the DCI is transporting a TDD configuration.

As a modification, a TDD-DCI receive window is specified, which should be understood as limiting where the mobile station expects a TDD-DCI message for exactly specific subframes and/or radio frames. In other words, the preferably periodic nature of the subframes and/or radio frames is defined as a TDD-DCI receive window, where a TDD configuration message can be transmitted by the base station and/or only needs to be received and detected by the mobile station.

The first embodiment of the present invention provides a method for specifying one of a plurality of time division duplex, TDD, configurations for a mobile station in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The mobile station receives from the base station the downlink control information and the corresponding downlink control information error detection code, the error detection code being scrambled by the base station with an identifier associated with the TDD configuration. Then, the mobile station determines the identifier used for scrambling the downlink control information error detection code. The mobile station determines the TDD configuration from the identifier used to scramble the downlink control information error detection code.

According to a useful modification of the first embodiment, which may be used, in addition or alternatively to the above, each TDD configuration is associated with a different identifier value, and a particular TDD configuration is encoded into an error detection code by scrambling the error detection code with the associated identifier. In one embodiment, the identifier is a temporary radio network identifier of 16 bits.

According to a useful modification of the first embodiment, which can be used in addition to or alternatively to the above, the relationship between a plurality of TDD configurations and identifiers is predefined in the base station, and the mobile station is informed of the predefined relationship by a configuration message.

According to a useful modification of the first embodiment, which may be used in addition to or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is 1C format downlink control information. For this particular case, in an additional embodiment, the downlink control information further comprises an invalid parameter indicating that the downlink control information indicates one of a plurality of TDD configurations. The invalid parameter may be a resource block assignment parameter having a length of 3-9 bits and an invalid value such as all bits of the resource block assignment parameter equal to "1".

According to a useful modification of the first embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information contains an invalid parameter with one of a plurality of invalid values. All of the plurality of invalid values indicate that the downlink control information indicates one of the plurality of TDD configurations. On the other hand, each or group of invalid values of an invalid parameter indicates at least one of the following:

the target cell for which the TDD configuration is to be applied,

a HARQ instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the mobile station for communication, for the cell to which the TDD configuration is to be applied,

a valid time parameter for said TDD configuration, such that the mobile station determines the amount of time for which said TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter indicates an index associated with a predetermined time value,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the first embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information comprises at least one of the following:

target cell identifier identifying the target cell for which the TDD configuration is to be applied, preferably wherein the target cell identifier is 1-5 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon application of said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration such that the mobile station determines the amount of time for which the specified TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter is 1-2 bits long and indicates an index associated with a predefined the amount of time

padding field with a bit value such that the mobile station determines whether the bit value of the padding field is identical to the predefined bit value, preferably the additional field is 1-32 bits long,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the first embodiment of the invention, which may be used in addition to or alternatively to the above, the mobile station is configured with a default TDD configuration. The mobile station applies the defined TDD configuration for n+m radio frames and applies the default TDD configuration for n+m+1 radio frames. m>=1, and n is associated with a radio frame in which the downlink control information and the error detection code are received by the mobile station.

The first embodiment of the present invention provides a mobile station for handling one of a plurality of time division duplex, TDD, communication configurations in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The receiving section of the mobile station receives the downlink control information and the corresponding error detection code for the downlink control information from the base station. The error detection code is scrambled by the base station with an identifier associated with the TDD configuration. The mobile station processor determines the identifier used to scramble the downlink control information error detection code. The mobile station processor further determines the TDD configuration from the identifier used to scramble the downlink control information error detection code.

According to a useful modification of the first embodiment of the invention, which can be used in addition to or alternatively to the above, the receiver receives from the base station information about the relationship between a plurality of TDD configurations and identifiers.

According to a useful modification of the first embodiment, which may be used in addition to or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is 1C format downlink control information. In this case, the processor may determine that the downlink control information indicates one of the plurality of TDD configurations from the downlink control information containing the invalid parameter. In one embodiment, the invalid parameter is a resource block assignment parameter having a length of 3-9 bits and an invalid value such as all resource block assignment parameter bits equal to "1".

According to a useful modification of the first embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information contains an invalid parameter with one of a plurality of invalid values. The mobile station processor determines that the downlink control information indicates one of a plurality of TDD configurations based on any of the invalid values. In addition, the processor determines, based on the particular invalid value of the invalid parameter in the downlink control information, at least one of the following:

the target cell for which the TDD configuration is to be applied;

a HARQ instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied,

a validity time parameter indicating the amount of time for which the specified TDD configuration is to be applied, preferably wherein the validity time parameter indicates an index associated with a predetermined time value,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the first embodiment of the invention, which may be used in addition or alternatively to the above, the mobile station processor determines from the downlink control information at least one of the following:

target cell identifier identifying the target cell for which the TDD configuration is to be applied, preferably wherein the target cell identifier is 1-5 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon applying said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration, from which the processor is adapted to determine the amount of time for which the specified TDD configuration should be applied, preferably wherein the valid time parameter has a length of 1-2 bits and indicates an index associated with a predefined time value,

a bit value of the padding field, such that the mobile station determines whether the bit value of the padding field is identical to the predetermined bit value, preferably the additional field has a length of 1-32 bits,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the first embodiment of the invention, which may be used in addition to or alternatively to the above, the mobile station is configured with a default TDD configuration. The processor applies the defined TDD configuration for n+m radio frames, and applies the default TDD configuration for n+m+1 radio frames, where m>=1 and n is associated with the radio frame in which the downlink control information and error detection code are received by the mobile station.

The first embodiment of the present invention provides a base station for specifying one of a plurality of time division duplex, TDD, configurations for a mobile station in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The base station processor decides on the TDD configuration and generates the downlink control information and the corresponding error detection code for the downlink control information. The processor further scrambles the generated error detection code with an identifier associated with the particular TDD configuration. The transmitter transmits the generated downlink control information and the scrambled error detection code to the mobile station.

A second embodiment of the present invention provides a method for specifying one of a plurality of time division duplex, TDD, configurations for a mobile station for at least one target cell in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The mobile station receives from the base station of the first cell the downlink control information and the corresponding error detection code for the downlink control information. The downlink control information error detection code is scrambled by the base station with a target cell ID associated with at least one target cell to which the TDD configuration is to be applied. The mobile station determines the identifier used to scramble the downlink control information error detection code. The mobile station also determines the TDD configuration from the downlink control information in case the determined ID is the target cell ID, and determines at least one target cell to which the determined TDD configuration is to be applied from the target cell ID used for scrambling. downlink control information error detection code.

According to a useful modification of the second embodiment of the invention, which may be used in addition or alternatively to the above, the first cell is operated in a frequency division duplex mode, and at least one target cell is operated in a TDD mode. The downlink control information and the error detection code are transmitted by the base station from the first cell.

According to a useful modification of the second embodiment of the invention, which can be used in addition or alternatively to the above, the target cell identifier either identifies a single target cell or a group of target cells from all cells. According to a useful modification of the second embodiment, which can be used in addition to or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is 1C format downlink control information. In a specific embodiment, the downlink control information further comprises an invalid parameter indicating that the downlink control information indicates one of a plurality of TDD configurations. The invalid parameter may be a resource block assignment parameter having a length of 3-9 bits and an invalid value such as all bits of the resource block assignment parameter equal to "1".

According to a useful modification of the second embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information contains an invalid parameter with one of a plurality of invalid values. All of the plurality of invalid values indicate that the downlink control information indicates one of the plurality of TDD configurations. On the other hand, each or group of invalid values of an invalid parameter indicates at least one of the following:

TDD configuration,

a HARQ instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied,

a valid time parameter for the specified TDD configuration, such that the mobile station determines the amount of time for which the specified TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter indicates an index associated with the predetermined time value,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the second embodiment of the invention, which may be used in addition or alternatively to the above, wherein the downlink control information comprises at least one of the following:

a TDD configuration field indicating a TDD configuration, preferably wherein the TDD configuration field is 3 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon applying said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration, such that the mobile station determines the amount of time for which the specified TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter is 1-2 bits long and indicates an index associated with a predefined the amount of time

padding field with a bit value such that the mobile station determines whether the bit value of the padding field is identical to the predefined bit value, preferably the additional field is 1-32 bits long,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the second embodiment of the invention, which can be used in addition or alternatively to the above, the mobile station is configured with a default TDD configuration and applies a certain TDD configuration for n+m radio frames, and applies a default TDD configuration for n+m+1 radio frames. . m>=1, and n is associated with a radio frame in which the downlink control information and the error detection code are received by the mobile station.

A second embodiment of the present invention provides a mobile station for handling one of a plurality of time division duplex, TDD, communication configurations in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The receiving section of the mobile station receives the downlink control information and the corresponding error detection code for the downlink control information. The downlink control information error detection code is scrambled by the base station with a target cell ID associated with at least one target cell to which the TDD configuration is to be applied. The mobile station processor determines the identifier used to scramble the downlink control information error detection code. The processor determines the TDD configuration from the downlink control information in case the determined identifier is the target cell identifier. The processor determines at least one target cell to which the particular TDD configuration is to be applied from the target cell ID used to scramble the error detection code for the downlink control information.

According to a useful modification of the second embodiment, which can be used in addition to or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is 1C format downlink control information. The processor determines that the downlink control information indicates one of the plurality of TDD configurations from the downlink control information containing the invalid parameter. The invalid parameter may be a resource block assignment parameter having a length of 3-9 bits and an invalid value such as all bits of the resource block assignment parameter equal to "1".

According to a useful modification of the second embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information contains an invalid parameter with one of a plurality of invalid values. The processor determines that the downlink control information indicates one of a plurality of TDD configurations based on any of the invalid values. The processor determines, based on the specific invalid value of the invalid parameter in the downlink control information, at least one of the following:

TDD configuration,

a HARQ instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied,

a valid time parameter indicating the amount of time for which the specified TDD configuration should be applied from the valid time parameter, preferably wherein the valid time parameter indicates an index associated with a predetermined time value,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the second embodiment of the invention, which may be used in addition or alternatively to the above, the processor determines from the downlink control information at least one of the following:

the TDD configuration field from the TDD configuration field, preferably where the TDD configuration field is 3 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon applying said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration, from which the processor is adapted to determine the amount of time for which the specified TDD configuration should be applied, preferably wherein the valid time parameter has a length of 1-2 bits and indicates an index associated with a predefined time value,

a bit value of the padding field, such that the mobile station determines whether the bit value of the padding field is identical to the predetermined bit value, preferably the additional field has a length of 1-32 bits,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the second embodiment of the invention, which may be used in addition to or alternatively to the above, the mobile station is configured with a default TDD configuration. The processor applies the defined TDD configuration for n+m radio frames, and applies the default TDD configuration for n+m+1 radio frames, where m>=1 and n is associated with the radio frame, where the downlink control information and error detection code are received by the mobile station .

A second embodiment of the present invention provides a base station for specifying one of a plurality of time division duplex, TDD, configurations for a mobile station in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The base station processor decides on the TDD configuration. The processor generates the downlink control information and the corresponding error detection code for the downlink control information, the downlink control information indicates the decision TDD configuration. The processor scrambles the generated error detection code with a target cell ID associated with at least one target cell to which the TDD configuration is to be applied. The transmitter transmits the generated downlink control information and the scrambled error detection code to the mobile station.

A third embodiment of the present invention provides a method for specifying one of a plurality of time division duplex, TDD, configurations for a mobile station in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The mobile station receives downlink control information from the base station, wherein the downlink control information indicates a TDD configuration and further comprises an invalid parameter indicating that the downlink control information indicates one of a plurality of TDD configurations. The mobile station determines whether the received downlink control information contains an invalid parameter. The mobile station determines the TDD configuration from the downlink control information in case the received downlink control information contains an invalid parameter.

According to a useful modification of the third embodiment of the invention, which can be used in addition or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is the downlink control information in 1C format, and the invalid parameter is a resource block assignment parameter, having a length of 3-9 bits and an invalid value such as all bits of the resource block assignment parameter equal to "1".

According to a useful modification of the third embodiment of the invention, which may be used in addition to or alternatively to the above, the invalid parameter may take on one of a plurality of invalid values. All of the set of invalid values indicate that the downlink control information indicates one of the set of TDD configurations, and each or group of invalid values indicates at least one of the following:

TDD configuration;

a target cell identifier identifying a target cell to which the TDD configuration is to be applied;

a HARQ instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied upon applying the specified TDD configuration;

a valid time parameter for the specified TDD configuration, such that the mobile station determines the amount of time for which the specified TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter indicates an index associated with the predetermined time value;

a buffer status report procedure instruction causing the current buffer status report procedure to be canceled or a new buffer status report procedure to be initiated upon applying the specified TDD configuration;

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration;

a random channel access procedure instruction for canceling the current random channel access procedure or initiating a new random channel access procedure upon applying the specified TDD configuration;

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the third embodiment of the invention, which may be used in addition or alternatively to the above, the downlink control information comprises at least one of the following:

a TDD configuration field indicating a TDD configuration, preferably wherein the TDD configuration field is 3 bits long,

target cell identifier identifying the target cell for which the TDD configuration is to be applied, preferably wherein the target cell identifier is 1-5 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon applying said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration, such that the mobile station determines the amount of time for which the specified TDD configuration is to be applied from the valid time parameter, preferably wherein the valid time parameter is 1-2 bits long and indicates an index associated with a predefined the amount of time

a bit value padding field such that the mobile station determines whether the bit value of the padding field is identical to the predetermined bit value, preferably the additional field is 1-32 bits long,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the third embodiment of the invention, which can be used in addition or alternatively to the above, the mobile station receives from the base station an error detection code for the received downlink control information, the error detection code for the downlink control information is scrambled by the base station with the identifier system information. The predefined system information receiving windows are uniquely associated with particular system information messages. The mobile station receives the downlink control information and the corresponding error detection code scrambled with the system information identifier within one of said system information reception windows that is not used by the base station to transmit system information as a result of configured periodicities for system information messages.

According to a useful modification of the third embodiment of the invention, which may be used in addition to or alternatively to the above, the mobile station is configured with a default TDD configuration. The mobile station applies the defined TDD configuration for n+m radio frames, and applies the default TDD configuration for n+m+1 radio frames, where m>=1, and n is associated with the radio frame in which the downlink control information and error detection code are received mobile station.

A third embodiment of the present invention provides a mobile station for handling one of a plurality of time division duplex, TDD, communication configurations in a communication system. The TDD configuration defines uplink, downlink and special subframes in one or more radio frames. The receiving section of the mobile station receives downlink control information from the base station, wherein the downlink control information indicates a TDD configuration and further comprises an invalid parameter indicating that the downlink control information indicates one of a plurality of TDD configurations. The mobile station processor determines whether the received downlink control information contains an invalid parameter. The processor further determines the TDD configuration from the downlink control information in case the received downlink control information contains an invalid parameter.

According to a useful modification of the third embodiment of the invention, which can be used in addition or alternatively to the above, the communication system is an LTE communication system, and the downlink control information is downlink control information in 1C format. The invalid parameter is a resource block assignment parameter having a length of 3-9 bits and an invalid value such as all bits of the resource block assignment parameter equal to "1".

According to a useful modification of the third embodiment of the invention, which may be used in addition to or alternatively to the above, the invalid parameter may take on one of a plurality of invalid values. The processor determines that the downlink control information indicates one of a plurality of TDD configurations based on any of the invalid values. The processor, based on the specific invalid value of the downlink control information invalid parameter, determines at least one of the following:

TDD configuration,

target cell identifier identifying the target cell for which the TDD configuration is to be applied,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied upon applying the specified TDD configuration,

a valid time parameter indicating the amount of time for which the specified TDD configuration should be applied from the valid time parameter, preferably wherein the valid time parameter indicates an index associated with a predetermined time value,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the third embodiment of the invention, which may be used in addition or alternatively to the above, the processor determines from the downlink control information at least one of the following:

the TDD configuration field from the TDD configuration field, preferably where the TDD configuration field is 3 bits long,

target cell identifier identifying the target cell for which the TDD configuration is to be applied, preferably wherein the target cell identifier is 1-5 bits long,

a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of the mobile station for communication for the cell to which the TDD configuration is to be applied, upon applying said TDD configuration, preferably wherein the HARQ instruction is 1 bit long,

a valid time parameter for the specified TDD configuration, from which the processor is adapted to determine the amount of time for which the specified TDD configuration should be applied, preferably wherein the valid time parameter has a length of 1-2 bits and indicates an index associated with a predefined time value,

a bit value of the padding field, such that the mobile station determines whether the bit value of the padding field is identical to the predetermined bit value, preferably the additional field has a length of 1-32 bits,

a buffer status report procedure instruction to cancel the current buffer status report procedure or initiate a new buffer status report procedure, upon application of the specified TDD configuration,

a scheduling request procedure instruction for canceling the current scheduling request procedure or initiating a new scheduling request procedure upon applying the specified TDD configuration,

a random channel access procedure instruction to cancel the current random channel access procedure or to initiate a new random channel access procedure by applying the specified TDD configuration,

a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration.

According to a useful modification of the third embodiment of the invention, which can be used in addition or alternatively to the above, the receiving section receives from the base station an error detection code for the received downlink control information, wherein the error detection code for the downlink control information is scrambled by the base station with the identifier system information. Predefined system information receiving windows are uniquely associated with specific system information messages. The receiving section receives the downlink control information and the corresponding error detection code scrambled with the system information identifier within one of said system information receive windows that is not used by the base station to transmit system information as a result of configured periodicities for system information messages.

According to a useful modification of the third embodiment of the invention, which may be used in addition to or alternatively to the above, the mobile station is configured with a default TDD configuration. The processor applies the defined TDD configuration for n+m radio frames, and applies the default TDD configuration for n+m+1 radio frames, where m>=1 and n is associated with the radio frame, where the downlink control information and error detection code are received by the mobile station .

A third embodiment of the present invention provides a base station for specifying one of a plurality of time division duplexing, TDD, patterns for a mobile station in a communication system, wherein the TDD pattern specifies uplink, downlink, and special subframes in one or more radio frames. The base station processor decides on the TDD configuration. The processor generates the downlink control information and the corresponding error detection code for the downlink control information, the downlink control information indicates the TDD configuration of the decision made, and includes an invalid parameter indicating that the downlink control information indicates one of a plurality of TDD configurations. . The base station transmitter transmits the generated downlink control information to the mobile station.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described more specifically with reference to the accompanying figures and drawings.

1 shows an exemplary 3GPP LTE system architecture,

Fig. 2 shows an exemplary general representation of the general E-UTRAN architecture in 3GPP LTE,

3 shows exemplary subframe boundaries in a downlink component carrier as defined for 3GPP LTE (Release 8/9),

4 shows an exemplary downlink resource grid for a downlink timeslot as defined for 3GPP LTE (Release 8/9),

5 is an illustration of a processing structure for single downlink control information as defined by 3GPP,

6 shows the seven currently standardized 0-6 configurations for UL/DL TDD, the respective definitions of 10 subframes and their switch point periodicity,

7 is an illustration of the structure of a radio frame composed of two half-frames and 10 sub-frames for a switching point periodicity of 5 ms,

Fig. 8 shows the seven currently standardized 0-6 configurations for UL/DL TDD of Fig. 6, and exemplary connectivity to the seven TDD-RNTIs according to the first embodiment,

9 is an illustration of a basic block diagram for the operation of a mobile station according to the first embodiment of the invention,

Fig. 10 shows seven currently standardized configurations 0-6 for UL/DL TDD of Fig. 6, and exemplary connectivity with seven TDD configuration indicator values according to the second and third embodiments,

Fig. 11 is a schematic illustration of a scenario with many small cells and one macro cell, called the enhanced Local area,

Fig. 12 is an illustration of the main block diagram for the operation of the mobile station according to the second embodiment,

Fig. 13 is an illustration of the main block diagram for the operation of the mobile station according to the third embodiment, and

14 shows two radio frames with different UL/DL TDD configurations along with some timings for data transmissions and feedback.

DETAILED DESCRIPTION OF THE INVENTION

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

The term "TDD configuration" refers to the Uplink/Downlink configuration in TDD as defined in the current standard, where the TDD configuration specifies for each radio frame subframe whether it is a downlink subframe, an uplink subframe, or a special subframe. The term "TDD Configuration Index" is a number (currently 0-6) respectively associated with one of the seven possible UL/DL TDD configurations and defined in the 3GPP technical standards (see FIG. 6).

The term "default TDD configuration" as used in the claims, as well as throughout the specification, refers to a TDD configuration that is configured "semi-statically" in the system using SIB1, as explained in the prior art section. In another formulation, the default TDD configuration is such that one TDD configuration broadcasts to all UEs in the communication area of the base station using the conventional system information collection and modification procedure mechanism. Of course, the "TDD default configuration" can also be changed during communication, although not as dynamically as with the present invention, but over an extended operating period.

The term "scrambling" as used in the claims in connection with an error detection code and used in the Detailed Description of the invention mainly in connection with CRC (as an example of an error detection code), refers to the process of implicitly encoding, for example, an identifier into an error detection code. (CRC). The term "masking" is considered equivalent in this application.

The term "invalid parameter" as used in the claims and description should be understood broadly as a parameter having an invalid value, thus forming an invalid parameter.

In the following, several embodiments of the invention will be explained in detail. The explanations are not to be understood as limiting the invention, but merely as examples of embodiments of the invention for a better understanding of 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 be applied to various scenarios and in ways that are not explicitly described in the document. Accordingly, the following scenarios, provided for purposes of explaining the various embodiments, will not limit the invention as such.

The various embodiments explained for the invention relate generally to TDD configurations and in particular provide a fast mechanism for dynamically changing a TDD configuration from a default TDD configuration (configured by SIB) to a target TDD configuration.

As explained in the background section, the prior art semi-static TDD configuration reconfiguration is slow and cumbersome and will be improved by a dynamic process according to one of the various embodiments explained below.

The three following embodiments use a DCI transmission from a base station to indicate a TDD reconfiguration for one or more cells. The TDD configuration may either be implicitly encoded into said transmission (in a CRC, as for the first embodiment), or more directly as a DCI part parameter (as for the second and third embodiments), or encoded in a transport block that is indicated by the DCI.

First Embodiment

According to a first set of embodiments of the invention, the TDD configuration is encoded in a CRC for DCI, both of which are transmitted (typically broadcast) from a base station for a particular radio cell.

For this purpose, seven different RNTIs are defined, such as at a base station or other entity in the network, with each of the seven different RNTIs associated with one of the seven TDD patterns, such that each TDD pattern 0-6 is associated with one different RNTI. 8 illustrates a possible relationship where TDD_0-6_RNTI values are associated with TDD configurations. The RNTI cost is thus strictly limited by the number of TDD configurations, and is not related to the number of small cells in the eLA scenario (see second embodiment below) for example. RNTIs for TDD are preferably 16-24 bits long and can be freely chosen, but are preferably chosen from the FFEO-FFFC range in hexadecimal notation for the 16-bit case and can be specified in a manner similar to what is currently done for M-RNTI, P-RNTI , SI-RNTI, or be defined and configured by the base station and communicated to mobile device receivers by transmission of RRC configuration messages or system information.

In one modification of the first embodiment (which also applies to the second and third embodiments), not all seven TDD configurations are subject to binding. In this case, there is no need for seven different RNTIs, but for example four TDD-RNTIs are sufficient to distinguish between the necessary TDD configurations that will be available for dynamic TDD reconfiguration according to the invention.

Relationships "TDD-RNTI - TDD Configuration" may be indicated in the same way as currently M-RNTI, P-RNTI, SI-RNTI, or defined and configured by the base station and transmitted to the mobile station(s); and possibly to the base station(s), in case another network entity decides. This can be done in various other ways, and the particular method used is not critical to the operation of the invention. For example, the table relationship in FIG. 8 may be transmitted using RRC messages, system information messages, or may be created during connection establishment. Accordingly, both the base station and the mobile station have the information necessary to implement the dynamic TDD reconfiguration according to the first embodiment.

The base station may decide at some point in time that the default TDD configuration is not optimal and that a different TDD configuration would be more beneficial. This may, for example, be due to a different traffic situation or similar circumstances. The base station thus decides on a target TDD configuration (out of the available remaining six TDD configurations) other than the default TDD configuration and performs dynamic TDD reconfiguration as follows.

The base station, after deciding on a new TDD configuration for specific cell(s), generates a DCI (of a new or known format, or a known format, but as an extension to it, see below), and then calculates an error detection code (3GPP uses CRC as an error detection code) for the generated DCI. In the prior art, the CRC would be scrambled with any of the various RNTIs, depending on the type of DCI being transmitted. In this case, the CRC computed for DCI is scrambled with the TDD-RNTI associated with a specific target TDD configuration, e.g. TDD_1_RNTI for TDD configuration 1 (see FIG. 8; and provided that the default TDD configuration is not 1TDD). The actual TDD CRC and RNTI scrambling may be performed in a conventional manner, as is well known in the art and explained in the background section as an example for 3GPP LTE.

After the base station has generated the DCI, computed the CRC, and scrambled the CRC with the corresponding TDD RNTI, the DCI and the scrambled CRC are transmitted in the cell. The DCI/CRC message may be sent on the PDCCH or ePDCCH, and preferably in the common search area of those, in case many or all mobile stations need to be informed of the reconfiguration. In other cases, transmission in a UE-specific search area may be more efficient since the transmission parameters can be tailored to the intended recipient and the respective prevailing transmission conditions.

According to one modification of the embodiment, one of the downlink control information messages already available, as defined by 3GPP and briefly discussed in the prior art section, is reused for the said purpose. In other words, the base station reuses one of Format 0, 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C DCI, 2D, 3, 3A, 4 (as defined at the time of this application; or any other format defined by 3GPP in the future) for dynamic TDD reconfiguration instead of the actual intended purpose of a particular DCI format message.

For example, a Format 1C DCI message, which has the fewest bits of all available DCI formats, can be reused. It should be noted that while in the following description, also mainly for the second and third embodiments, the 1C format for DCI is used to illustrate the principles of the invention, other DCI formats may be reused for the purposes of the invention.

The 1C DCI format in 3GPP is defined to include the following fields:

- resource block assignment (RBA) 3-9 bits (depending on the bandwidth);

- modulation and coding scheme (MCS) 5 bits;

- 1 bit guard interval value pointer (only if bandwidth >= 50 PRB).

A more specific discussion of the contents of DCI Format 1C can be found in Chapter 5.3.3.1.4 of 3GPP TS 36.212, hereby incorporated by reference. Thus, a 1C DCI format message may be between 8 and 15 bits long.

Accordingly, instead of sending the above parameters for PDSCH assignment as intended for DCI Format 1C, the base station may include other parameters in the DCI. This depends in part on the bandwidth in the cell, since the number of bits available in DCI Format 1C is bandwidth dependent. These other parameters to be included in DCI Format 1C may contain at least one of the following:

- target cell identifier identifying the target cell for which the TDD configuration as implicitly encoded in the CRC for DCI is to be applied,

- a HARQ instruction for instructing the mobile station(s) to restart or not to restart the HARQ protocol upon applying the new TDD configuration,

- a time-out parameter for the encoded TDD configuration indicating to the mobile station(s) the amount of time that said TDD configuration should apply before switching back to the default TDD configuration,

- a padding field with a predefined bit value (virtual CRC) that can be used to "pad" the DCI so that the remaining otherwise unused bits are put to good use in order to reduce the risk of a false alarm,

- a buffer status report (BSR) procedure instruction to cancel the pending BSR procedure or to initiate a new BSR procedure, upon application of the specified TDD configuration,

- a scheduling request (SR) procedure instruction instructing to cancel the pending SR procedure or to initiate a new SR procedure, upon application of the specified TDD configuration,

- a random access channel (RACH) procedure instruction instructing to cancel a pending RACH procedure or to initiate a new RACH procedure, upon application of the specified TDD configuration,

- a power headroom report (PHR) instruction to cancel the pending PHR or initiate a new PHR, upon application of the specified TDD configuration.

These parameters are only briefly discussed above for purposes of illustration and will be explained in more detail below.

When using such known DCI format, it is also possible for the base station to set one of the parameters set for said known DCI format to an invalid value, and thus use the invalid parameter as a "switch code point" to indicate to the mobile station that the DCI carrying invalid parameter, is not normal, but carries a UL/DL TDD configuration indicator. The DCI message thus includes said special (invalid) parameter as a normal DCI message, however with an invalid value. This invalid value is known to both the base station and the mobile station. Taking the already standardized DCI format 1C as an example, the resource block assignment parameter may be set to an invalid value, such as all bit values are "1".

An invalid value for a parameter or combination of parameters can generally be characterized as representing a state that is reserved or contrary to the requirements for the specified parameter. For example, an invalid resource block assignment value is one that would result in the assignment of at least one resource block with a negative index, or at least one resource block outside of the available resource blocks. Another example of an invalid value relates to the HARQ process number parameter in the case of TDD with a HARQ index that indicates a HARQ process beyond the specified maximum number of HARQ processes as specified in Table 7-1 in 3GPP TS 36.213. An example of a combination of invalid parameters, where the value represents a reserved state, is 'precoding information' as available, for example, in DCI format 2, where depending on the number of specified transport blocks, different values of precoding information are defined as 'reserved', and where the number of the specified transport blocks depends on the combination of the specified modulation and coding scheme and redundancy version as specified in chapter 7.1.7.2 in 3GPP TS 36.213.

For resource allocation type 2, at least one RBA state is invalid for all downlink PRBs 6-110, namely when all bit values are set to "1". For 10 and 13 PRBs there is exactly one invalid state, already mentioned all bits = 1. For 6 PRBs there are 2 invalid RBA values. For 15 PRBs, there are 4 invalid RBA values. For 25 PRBs, there are 50 invalid RBA values. For 50 PRBs, there are 62 RBA invalids for bin 1 and 83 RBA invalids for bin 2. For 75 PRBs, there are 120 RBA invalids, and for 100 and 110 PRBs, there are 212 RBA invalids.

Specifically, in the presence of a frequency band where there is more than one invalid value (i.e., all except for 10 and 13 PRBs, which, however, are less important in practice), additional information may be encoded into this DCI invalid parameter in addition to indicating that A DCI carrying an invalid parameter carries a UL/DL TDD configuration indicator. The additional information may be one of the above other parameters, namely at least one of the target cell ID, the HARQ instruction and the validity time parameter, the BRS instruction, the SR instruction, the RACH instruction, and the PHR instruction. Of course, if one of these parameters is encoded into an invalid parameter, then the DCI shall not include said particular parameter separately in its payload.

For example, considering a bandwidth of 15 PRBs with 4 RBA invalids, all of the 4 RBA invalids indicate to the MS that the DCI carrying said RBA invalid includes a TDD dynamic configuration indicator. In addition, each particular RBA invalid value may further be associated with one different validity time parameter (eg, 10 ms, 40 ms, 100 ms, and 200 ms), or differentiate between different target cells for which the TDD configuration should be applied (eg, PCell, SCell1, SCell2 or SCell3).

Alternatively, 2 of the RBA invalids are associated with the "restart HARQ" instruction, and the remaining 2 RBA invalids are associated with the "do not restart HARQ" instruction. Similar considerations apply for other frequency bands; for example, when only 2 invalid states are available for the RBA parameter, then only two different states for additional information can be encoded, such as a HARQ instruction, or a valid time parameter (eg, distinguishing valid periods of 10 ms and 40 ms).

As an alternative to reusing a known DCI format (such as Format 1C), it is also possible to create an extension of the known DCI format such that the known DCI format is only used for specific cases and another "version" of the known DCI format is used for other specific cases. For example, it will be possible to adapt a known DCI format (such as Format 1C) to be applicable only for specific radio frames or subframes within specific radio frames, and include a definition that specifies the known DCI format to be used for dynamic UL/DL reconfiguration. TDD, for other radio frames or other subframes within specific radio frames, where depending on the "version" the DCI format may contain different information elements.

As an alternative to the above, it is also possible to use a DCI format specifically defined for the purpose of dynamic TDD reconfiguration; for example, also having a different size than already defined DCI formats. In this case, the number of DCI bits is independent of the cell bandwidth, but can be set freely depending on the parameters to be transmitted in this new DCI. For example, DCI Format 1E may be defined, which includes at least one of the above parameters (target cell ID, HARQ instruction, validity time parameter, padding field, BSR instruction, SR instruction, RACH instruction, PHR instruction).

So, the base station transmits the DCI and the scrambled CRC in its cell, and the mobile station(s) in the cell receive the DCI and the scrambled CRC. The processing of DCI and CRC according to this first embodiment is explained in connection with FIG. 9, which shows a block diagram of a mobile station for a basic first embodiment of the invention.

The mobile station listens on the PDCCH and EPDCCH to detect DCI messages destined for the mobile station. After receiving the DCI and CRC from the base station, the mobile station proceeds to determine the RNTI with which the CRC was scrambled. Particular error checking and descrambling may be performed in the usual manner, as discussed in the examples in the prior art section for 3GPP LTE. For example, the mobile station performs error checking for DCI based on the CRC, DCI, and various possible candidate identifiers that may have been used to scramble the DCI out of the seven TDD RNTIs. For only one of the RNTIs, the CRC check performed by the mobile station is successful. Thus, the mobile station determines that one particular TDD RNTI has been used for scrambling.

The mobile station then proceeds to determine which TDD configuration the determined TDD RNTI is associated with, for example, by referring to a table as defined in FIG. Thus, for example, the mobile station determines that it should switch to TDD configuration 1 instead of continuing to use the default TDD configuration.

The TDD configuration thus determined is then applied by the mobile station for a specific time. This may either be preset to be a fixed amount of time such as 1, 2 or 4 radio frames. Alternatively, the time may be specified dynamically, for example, using the time-of-validation parameter already mentioned previously as being (optionally) part of the DCI payload or encoded into an invalid parameter (see above). Assuming that the mobile station receives a DCI/CRC transmission in radio frame n, it then processes the DCI and CRC accordingly and applies the specified TDD configuration for a specific number of radio frames n+1, n+2, n+3, etc., depending from the validity time parameter from the DCI or a predetermined fixed time value. After the dynamically specified TDD configuration expires, i.e., is no longer applicable, the MS switches back to the default TDD configuration until, for example, it receives another DCI TDD for dynamic UL/DL TDD reconfiguration.

Alternatively, the mobile station may also transition to applying the new TDD configuration until it receives another TDD reconfiguration; in other words, the new TDD configuration is not specified for a specific amount of time, but for an indefinite one, until otherwise specified.

The mobile station may also determine additional parameters from the DCI, depending on whether the DCI includes them. For example, the mobile station may determine the target cell, the HARQ instruction, the validity time parameter, the padding field value, the BRS instruction, the SR instruction, the RACH instruction, and/or the PHR instruction therefrom.

Details on how the information extracted from these additional parameters is used are explained below separately in connection with these parameters.

According to a further modification of the first embodiment, the CRC from the DCI is scrambled by the TDD-RNTI, although only one TDD-RNTI would be required for this purpose instead of multiple TDD-RNTIs where the DCI assigns physical resources to transmit a transport block in such a manner as, for example, in Currently, DCI format 1A can be used to assign physical resources to a transport block. Said transport block may then represent a MAC or RRC message that contains TDD (re-)configuration information and parameters, as outlined in subsequent sections of this application. In other words, instead of (or in addition to) using the DCI payload to indicate one or more TDD configuration parameters, the RNTI is used to identify that a reconfiguration message is being sent and the DCI payload gives information about the transport block that carries the TDD configuration parameter(s). .

Second Embodiment

The second embodiment of the invention mainly differs from the first embodiment explained above in that the UL/DL TDD configuration is not encoded in the RNTI used to scramble the DCI CRC, but instead the UL/DL TDD configuration indicator is included in the DCI payload. Most of the other details, however, remain the same between the first and second embodiments.

The UL/DL TDD configuration indicator in DCI distinguishes between 7 different UL/DL TDD configurations of FIG. 6; thus, a 3-bit field is sufficient to indicate a particular UL/DL TDD configuration, where each pointer value is associated with one of the TDD configurations. Again, it is also possible to distinguish between fewer UL/DL TDD configurations such that a 2-bit (or even 1-bit) field is already sufficient; however, with the disadvantage that dynamic TDD reconfiguration is not as flexible.

The relationship between the 3-bit values and TDD configurations may be set by the base station or other network entity. An exemplary relationship for all seven TDD configurations using a 3-bit TDD pointer field is illustrated in FIG. Relationship information between TDD configuration indicator values and actual TDD configurations is reported to the mobile station; and possibly to the base station(s), in case another network entity decides. As in the case of the first embodiment, the informing procedure can be carried out in various ways; for example, using RRC messages, system information messages, or may be done during connection establishment. Accordingly, both the base station and the mobile station have the necessary information to implement the dynamic TDD reconfiguration of the invention.

As for the first embodiment, the base station decides to change the UL/DL TDD configuration from the default TDD configuration to another TDD target configuration, for example, because the TDD target configuration is better suited to the current traffic. The base station thus wishes to perform dynamic TDD reconfiguration and generates a DCI including the above UL/DL TDD configuration indicator.

The base station thus generates a DCI for dynamic TDD reconfiguration, the DCI including a TDD configuration indicator indicating the TDD configuration that the base station has decided on. In addition, as already explained in detail for the first embodiment, the DCI may include additional parameters such as at least one of a HARQ instruction, a validity time parameter, an additional field, a BRS instruction, an SR instruction, a RACH instruction, and a PHR.

In the same way as for the first embodiment, the DCI generated by the base station may be one of the existing downlink control information messages as defined by 3GPP (e.g., DCI Formats 0, 1, 1A, 1B, 1C, 1D, 2, 2A , 2B, 2C, 2D, 3, 3A, 4). In this case, instead of sending the usual parameters of the specified DCI Format (such as RBA, MCS, interval value indicator for Format 1C), the base station includes other parameters. As explained above, the TDD configuration indicator field is included.

When using the known DCI format, it is also possible for the base station to invalidate one of the parameters set for said known DCI. The invalid parameter indicates to the MS that the DCI carrying the invalid parameter additionally carries a UL/DL TDD configuration indicator. This has been explained in detail for the first embodiment, and the same principles apply also to the second embodiment and are not repeated for the sake of brevity. Instead, the reader is kindly directed to the relevant excerpts from the first embodiment.

Furthermore, the invalid parameter can be understood not only to indicate to the mobile station that the DCI carries the UL/DL TDD reconfiguration indicator, but that the invalid parameter can encode an additional parameter such as a specific UL/DL TDD reconfiguration indicator, or any of the other parameters mentioned. above: HARQ instruction, action time parameter, BRS instruction, SR instruction, RACH instruction, PHR instruction. This is very similar to using the invalid parameter for the first embodiment, except that the invalid parameter for the first embodiment may encode the target cell ID but not the TDD configuration indicator, while it is different for the second embodiment.

As an alternative to reusing the known DCI format (such as the 1C format), it is also possible to create an extension of the known format, as already explained for the first embodiment. To avoid repetition, the reader is referred to the relevant sections of the first embodiment.

As a further alternative, it is also possible to use a DCI format specifically defined for the purpose of dynamic TDD reconfiguration, for example with a different size. Again, the reader is referred to the relevant sections of the first embodiment.

Regardless of the DCI format actually used, and regardless of whether the DCI includes or does not include additional parameters, the base station calculates an error detection code for a similarly generated DCI. According to the second embodiment, the error detection code (CRC) is then scrambled with a cell ID identifying the target cell(s) for which dynamic TDD reconfiguration is to be applied. The cell identifier may also be referred to as SC-RNTI, small cell RNTI.

Since the cell ID for CRC scrambling is considered to be the same length as the CRC, i.e. expected to be 16-24 bits long, it is particularly suitable for distinguishing many different cells and thus can be preferably used in scenarios where there is many hundreds. The 16-24-bit cell ID values can be flexibly associated with either single cells or another group of cells. This has the advantage that the base station can flexibly perform TDD reconfiguration for either single cells (eg, SCell1) and/or a group of cells (eg, neighboring cells SCell1-SCell10) by using a particular target cell ID value associated with it. In addition, one of the available target cell identifiers may also identify all cells as target cells. The relationship between the target cell ID values and the target cell (group) may be decided at the base station or other network entity, and then must be reported to the mobile station (and base station), so that both the base station and the mobile station have the same information, necessary for dynamic TDD reconfiguration according to the second embodiment. As for the first embodiment, it is not possible to use all the available RNTI values (65536 different values are available for the 16-bit RNTI case) because some of them are already reserved for other purposes. Alternatively, the relationships may be predefined and fixed according to the standard.

Existing mechanisms such as carrier indicator fields only support at most 8 different cells. LTE-Advanced, however, will support an extended Local Area (eLA) where many dozens of small cells may be within the coverage area of a macro cell. This is schematically illustrated in FIG. 11, where a macro cell with a large coverage area operates at about 800 MHz, and in it many cells with a small coverage area operate at about 3.4 GHz. In such a cell deployment, the mobile station may need to distinguish more than 7 small cells, especially if the mobile station moves through the coverage area of a macro cell and must perform radio measurements on multiple small cells to determine the one with the most favorable radio conditions.

So, the base station transmits DCI and scrambled CRC for DCI, and mobile stations located in the cell receive DCI and scrambled CRC. The DCI and CRC processing in the mobile station according to the second embodiment will be explained with reference to FIG.

The mobile station listens on the PDCCH and EPDCCH to detect DCI messages destined for the mobile station. Thus, the mobile station receives the DCI and CRC from the base station and determines the RNTI with which the CRC has been scrambled. Particular error checking and descrambling may be performed in a conventional manner as described illustratively in the 3GPP LTE prior art section. For example, the mobile station performs error checking for DCI based on the CRC, DCI, and various possible candidate IDs that may have been used for DCI scrambling, among these target cell IDs. For only one of the RNTIs, the CRC check performed by the mobile station is successful. Thus, the mobile station determines that one of the specific target cell IDs has been used for scrambling.

From the fact that the target cell ID was used to scramble the CRC, the mobile station can already deduce that the DCI further indicates a TDD configuration to perform dynamic TDD reconfiguration. Accordingly, the mobile station then proceeds to determine the particular DCI-encoded TDD pattern in one of various ways as explained above. Thus, the mobile station can either read the actual value of the TDD configuration indicator field as shown in FIG. 10 and associate the value with the corresponding TDD configuration; or the mobile station determines the value of the invalid parameter, and from the value of the invalid parameter determines the associated TDD configuration.

In addition, the mobile station determines, from the determined target cell ID, the specific target cell or cell group for which the encoded TDD configuration is intended and to be applied. The TDD reconfiguration should only be applied by the mobile station if the mobile station actually belongs to the identified target cell. Otherwise, the TDD reconfiguration may be ignored by the mobile station.

If included in the DCI, the mobile station may determine additional parameters from the DCI payload, for example, a lifetime parameter, a HARQ instruction, a padding field value, a BRS instruction, an SR instruction, a RACH instruction, and/or a PHR instruction. Details on how the information extracted from these additional parameters is used are explained below separately in connection with these parameters.

The TDD configuration thus determined is then applied by the mobile station for a specific time. As in the case of the first embodiment, this may either be preset to be a fixed amount of time such as 1, 2 or 4 radio frames. Alternatively, the time may be specified dynamically, for example by using the time-to-live parameter already mentioned previously as being (optionally) part of the DCI payload or encoded into an invalid parameter (see above). Assuming that the mobile station receives a DCI/CRC transmission in radio frame n, it then processes the DCI and CRC accordingly and applies the specified TDD configuration for a specific number of radio frames n+1, n+2, n+3, etc., depending from the DCI duration parameter or a predetermined fixed time value. After the dynamically specified TDD configuration expires, i.e., is no longer applicable, the mobile station switches back to the default TDD configuration until, for example, it receives another DCI TDD for dynamic UL/DL TDD reconfiguration.

Alternatively, the mobile station may also transition to applying the new TDD configuration until it receives another TDD reconfiguration; in other words, the new TDD configuration is not specified for a specific amount of time, but indefinitely, until otherwise instructed.

According to a modification of the second embodiment, the CRC for the DCI is scrambled according to the SC-RNTI, and the DCI assigns physical resources to transmit a transport block in a similar manner as, for example, the existing DCI format 1A can be used to assign physical resources to a transport block. Said transport block may then represent a MAC or RRC message that contains TDD (re)configuration information and parameters, such as the required TDD configuration or target cell index, or other parameters outlined in subsequent sections of this application.

Third Embodiment

The third embodiment of the invention is similar to the first and second embodiments in that it deals with dynamic UL/DL TDD reconfiguration using DCI/CRC transmission. In addition, like the second embodiment, the UL/DL TDD configuration is not implicitly encoded in the RNTI used for CRC scrambling, but is instead included in the DCI payload. However, according to the third embodiment, the target cell identifier (SC-RNTI) is not used for DCI CRC scrambling. However, the DCI includes an invalid parameter to indicate to the mobile station that the DCI additionally contains an indicator regarding the TDD configuration. In other words, the invalid parameter already discussed in connection with the first and second embodiments as being an optional DCI parameter intended for the third embodiment is always included in the DCI payload.

Otherwise, many of the details already discussed for the first and second embodiments remain the same for the third embodiment. For the reason mentioned, repetitions are avoided whenever possible and the reader is referred to the relevant excerpts of the first and/or second embodiment.

In the same manner as for the second embodiment, the UL/DL TDD configuration indicator in DCI distinguishes all 7 different UL/DL TDD configurations of FIG. 6; or alternatively, may distinguish between fewer UL/DL TDD configurations. Accordingly, the UL/DL TDD configuration indicator may be defined as illustratively depicted in FIG. To avoid repetition, the reader is referred to the sections of the second embodiment explaining in detail the UL/DL TDD configuration pointer; which may be included as a separate parameter in the DCI payload, or may be encoded into an invalid parameter when enough invalid values are available, as explained previously. In any case, both the base station and the mobile station must have a common understanding of how different TDD configurations can be indicated using DCI.

As already discussed for the first and second embodiments, the base station may at some point in time decide to change the UL/DL TDD configuration from the default TDD configuration to another UL/DL TDD configuration, for example, because the TDD configuration is better suited to the current traffic. The base station thereby wishes to perform dynamic TDD reconfiguration, as will be explained below in connection with the third embodiment.

The base station generates a DCI, the DCI including a TDD configuration indicator for indicating the TDD configuration that the base station has decided on. As explained for the first and second embodiments in detail, DCI may further include additional parameters; for this particular third embodiment: target cell ID, HARQ instruction, validity time parameter, padding field, BRS instruction, SR instruction, RACH instruction and/or PHR instruction.

Since the DCI according to the third embodiment always includes an invalid parameter, the DCI generated by the base station shall be one of the already available downlink control information messages as defined by 3GPP (e.g., Formats 0, 1, 1A, 1B, 1C, 1D, 2 , 2A, 2B, 2C DCI, 2D, 3, 3A, 4). This already defined DCI message is then reused to carry the TDD configuration indicator.

Furthermore, for the case where there are multiple invalid values available for the invalid parameter (especially for larger bandwidths), it is possible to encode at least one of the above additional parameters into an invalid parameter in the same manner as for the first and second embodiment.

For example, assuming the case where DCI Format 1C having the least number of bits is used, the RBA parameter in DCI Format 1C may be used as an invalid parameter and may be set to an invalid value. As explained in detail for the first embodiment, the RBA parameter may take on a different number of invalid values depending on the bandwidth used in the cell. One invalid value is the same for the entire bandwidth, namely where all bits of the RBA parameter are set to one. For most bandwidths, however, the RBA parameter may take several invalid values; for 6 PRBs, there are 2 invalid RBA values; for 15 PRBs, there are 4 invalid RBA values; for 25 PRBs, there are 50 invalid RBA values; for 50 PRBs, there are 62 RBA invalid values for slot 1, and 83 RBA invalid values for slot 2; for 75 PRBs, there are 120 RBA invalid values, and for 100 and 110 PRBs, there are 212 RBA invalid values.

Additional information may be encoded into this invalid DCI parameter other than indicating that the DCI carrying the invalid parameter carries a UL/DL TDD configuration indicator. The additional information may be one of the above other parameters, namely at least one of TDD configuration, target cell ID, HARQ instruction, lifetime parameter, BRS instruction, SR instruction, RACH instruction, and PHR instruction. Of course, if one of said parameters is encoded into an invalid parameter, then the DCI shall not contain said specific parameter separately in its payload.

Therefore, in one modification of the third embodiment (and in fact also the second embodiment), the 1C DCI format for dynamic TDD reconfiguration includes an RBA parameter set to invalid (but encoding a specific TDD configuration) and a padding field for the remaining bits, a field padding set to a predefined value and used as a virtual CRC.

The base station generates a DCI as explained above and then calculates an error detection code (CRC) for the thus generated DCI. The CRC is scrambled by the base station with RNTI; which RNTI is used is not important for the operation of the third embodiment, however, it is advantageous for the mobile station to limit the operation to only one or limited RNTI value(s) in order to minimize the risk of erroneously detecting a successful DCI transmission due to transmission errors. A useful modification of the third embodiment, where SI-RNTI is used for scrambling, will be explained further in detail below.

The base station transmits the DCI and the scrambled CRC for the DCI, and the mobile station(s) located in the cell receives the DCI and the scrambled CRC. The processing of DCI and CRC by the mobile station according to the third embodiment will be explained with reference to FIG.

The mobile station listens on the PDCCH and EPDCCH to detect DCI messages destined for the mobile station. Thus, the mobile station receives the DCI and CRC from the base station. The CRC is descrambled and the DCI content is processed.

The mobile station then determines whether the DCI contains an invalid parameter, and if it does, the mobile station concludes that the DCI is not a normal DCI, but is used by the base station for dynamic TDD reconfiguration, and thus indicates a specific TDD configuration. The mobile station then proceeds to determine the particular DCI-encoded TDD configuration in one of various ways as explained above. Namely, the mobile station can either read the actual value of the TDD configuration field as shown in Fig. 10 and associate the value with the corresponding configuration; or the mobile station determines the invalid parameter value and associates the determined invalid parameter value with the corresponding TDD configuration.

In addition, depending on whether the DCI includes additional parameters, the mobile station may determine the value of any other parameter in the DCI, such as target cell(s), validity time, HARQ instruction, BRS instruction, SR instruction, RACH instruction, and/or PHR instruction; whether the other parameter is encoded into an invalid parameter or present as a separate parameter in the DCI payload.

For example, the mobile station determines, from a certain target cell ID, a specific target cell or cell group for which the encoded TDD configuration is intended and to be applied. The TDD reconfiguration should only be applied by the mobile station if the mobile station actually belongs to the identified target cell. Otherwise, the TDD reconfiguration may be ignored by the mobile station. Details on how the information extracted from these additional parameters is used are explained below separately in connection with these parameters.

The TDD configuration thus determined is then applied by the mobile station for a specific time. As in the case of the first embodiment, this may either be preset to be a fixed amount of time such as 1, 2 or 4 radio frames. Alternatively, the time may be specified dynamically, for example using the time-of-validation parameter already mentioned previously as being (optionally) part of the DCI payload or encoded into an invalid parameter (see above). Assuming that the mobile station receives a DCI/CRC transmission in radio frame n, it then processes the DCI and CRC accordingly and applies the specified TDD configuration for a certain number of radio frames n+1, n+2, n+3, etc., depending from the DCI duration parameter or a predetermined fixed time value. After the dynamically specified TDD configuration expires, i.e., is no longer applicable, the mobile station switches back to the default TDD configuration until, for example, it receives another DCI TDD for dynamic UL/DL TDD reconfiguration.

Alternatively, the mobile station may also transition to applying the new TDD configuration until it receives another TDD reconfiguration; in other words, the new TDD configuration is not specified for a specific amount of time, but indefinitely until otherwise specified.

One improved modification of the third embodiment relates to the CRC for DCI scrambled by the base station with RNTI system information (SI-RNTI), and furthermore, the DCI TDD configuration transmitted in the SI receive window, which normally should not be used by the base station to send the system information information. This will be explained in detail below.

In the prior art, time domain scheduling for MIB and SIB1 messages is fixed at 40ms and 80ms, respectively. Each SI message is transmitted in a given, periodic time domain window, while the physical layer control signaling indicates in which subframes in that SI window is actually scheduled. The scheduling windows of the various SI messages (referred to as SI windows or SI receive windows) are sequential (ie, there is no overlap or gaps between them) and have an overall length that is configurable. SI windows may include subframes in which SI messages cannot be transmitted, such as subframes used for SIB1 and subframes used for uplink in TDD.

SI messages may have different periodicities. Therefore, in some clusters of SI windows, all SI messages are scheduled, while in other clusters only SI messages with shorter repetition periods are transmitted. For one example, an SI window cluster starting at System Frame Number (SFN) 0 contains all SI messages, and a cluster starting at another SFN may only contain the first SI message depending on predefined periodicities. For a more specific discussion of SI windows, please refer to the technical standard or The UMTS Long Term Evolution - From Theory to Practice, edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapters 3.2.2 and 3.2.2.1, incorporated herein by reference. .

As a result, depending on particular periodicities (especially for long repetition periods/cycles), there will be SI windows in which SI is not transmitted, and thus these SI windows will not be used by the base station to transmit system information. This can be used.

In one modification of the third embodiment, a DCI whose CRC is scrambled with the SI-RNTI is transmitted by the base station in one of said unused SI windows. The mobile station knows in advance that this particular SI window will not be used to transmit system information, since the mobile station is also aware of the SI reporting periods. Thus, when the mobile station receives an SI message (ie, a DCI TDD whose CRC is scrambled with the SI-RNTI), the mobile station knows that it cannot be a normal SI message. Accordingly, it is aware that this SI message received within the SI window, which should not normally be used by the base station to transmit the SI message, should be a TDD configuration message. In addition, the mobile station can confirm this by determining whether the DCI payload includes an invalid parameter.

In order to free the mobile station from the cost of detecting possible SI messages in SI windows that would not normally be used by the base station to transmit the SI message, a further modification of the third embodiment defines a "TDD-DCI receive window". The TDD-DCI receive window should be understood as restrictive, where the mobile station should only expect a TDD-DCI message for exactly specific subframes and/or radio frames. In other words, preferably a periodic pattern of - optionally, but not necessarily contiguous - subframes and/or radio frames is defined as a TDD-DCI receive window (or equivalent pattern) where a TDD-DCI message can be transmitted by the base station and/or only needs to be received and detection by the mobile station.

Such a window may be used in general with any of the described embodiments and regardless of the SI-RNTI used. For illustrative purposes, the following describes a situation where a TDD-DCI receive window is used and SI-RNTI is used to scramble the CRC for DCI. As mentioned above, the UE may know that the detected DCI is TDD DCI if the DCI is detected in an SI window that is not used for SI message transmissions, as a function of the configured SI cycles. Such unused SI windows may therefore occur more or less frequently. Therefore, it may be advantageous, in order to create more DCI TDD transmission opportunities, to define a TDD-DCI receive window. In case the subframe is part of the SI window in use and also part of the TDD-DCI receive window, preferably the mobile station associates the successfully detected DCI with the CRC scrambled by the SI-RNTI as being TDD-DCI and not used for the purpose of indicating SI transmission. Alternatively, in such a situation, the mobile station interprets such a DCI as TDD-DCI if an invalid parameter is detected in the DCI, and as a DCI to indicate SI transmission otherwise.

According to a modification of the third embodiment, the DCI CRC is scrambled by SI-RNTI. In case the mobile station detects this in an unused SI window and/or in a subframe defined as part of the TDD-DCI receive window, the mobile station knows that the DCI is for TDD configuration message. In this modification, DCI assigns physical resources to a transport block transmission in the same way that, for example, DCI format 1A can currently be used to assign physical resources to a transport block. Said transport block may then submit a MAC or RRC message that contains TDD (re)configuration information and parameters, such as a TDD configuration index or additional parameters outlined in subsequent sections of this application. Therefore, instead of (or in addition to) the TDD indicator in the DCI message, the transport block indicated by the DCI message contains the TDD indicator.

Extra options

The first, second, and third embodiments described above mention that the additional parameters may be included in the downlink control information used for dynamic UL/DL TDD reconfiguration, either as separate DCI parameters or encoded into an invalid parameter. These parameters have only been briefly described and will be explained in more detail below.

Target Cell ID

As is already apparent from the term, this identifier must identify the specific cell to which the UL/DL TDD configuration transmitted with DCI/CRC is to be applied. However, this parameter must be some used in DCI and may be different from that used for CRC scrambling in DCI, as explained for the second embodiment. For example, while the SC-RNTI used for scrambling is 16 bits, the target cell identifier to be included in the DCI payload may be any suitable size.

There may be scenarios in which one cell transmits a dynamic UL/DL TDD reconfiguration message, although the UL/DL TDD reconfiguration should be applied in another cell. This may be the case for the above Extended Local Area (eLA) scenario. Specifically, if the TDD configuration is for the SCell, then preferably the dynamic TDD reconfiguration may be passed to the PCell.

Depending on the number of different cells in the system, only a few bits are needed for the target cell ID to distinguish between different cells.

The target cell ID can be implemented in various ways. For example, the 3GPP-defined Release 8 Physical Cell Identification (PCID, in TS 36.211; PhysCellID in TS 36.331), PCID directly pointing to an index, may be used. Alternatively, the numbering currently used for adding and modifying SCell (parameters SCellIndex, sCellToAddModList, SCellToAddMod-r10, see e.g. TS 36.331 section 5.3.10.3b and other sections therein) may be used directly, or may a new relationship between the target cell ID and the target cell should be established.

Another way to implement the target cell ID is to use a 3-bit (component) carrier indicator (CIF) field. The CIF field is typically for cross-carrier scheduling and identifies the carrier to which the scheduling applies. The CIF can thus identify the other carrier, and thereby allows the mobile station to determine for which cell (carrier) the TDD configuration received with DCI should be applied. This preferably reuses numbering and relationships similar to the SCell addition and modification procedure (TS document 36.331, section 5.3.10.3b and the parameters SCellIndex, sCellToAddModList, SCellToAddMod-r10 described in other sections therein).

Another optional capability for the target cell ID is similar to the 3GPP Release 10 Coordinated Multipoint (COMP) method. Instead of pointing to a physical cell identifier, the target cell identifier points to one or more reference symbol resources or configurations, such as a CRS port or a CSI-RS resource, a resource as defined in TS 36.211, sections 6.10.1 and 6.10.5, and as defined in the CSI-RS-Config information element (PTC CSI configuration) in TS 36.311.

Another optional possibility for the target cell ID is to establish a new relationship between the target cell ID and the target cell.

Accordingly, the mobile station determines the target cell from this target cell ID included in the DCI.

Validity parameter

As explained in the background section, compared to other TDD reconfiguration methods based on, for example, MAC or RRC, TDD reconfiguration with DCI/CRC of the present invention should be on the order of 10 ms. Of course, the TDD dynamic reconfiguration pointer can only be valid for one radio frame; however, this would be overhead since the same TDD reconfiguration message would need to be sent every 10 ms.

According to another solution, the DCI may include a valid time parameter indicating the amount of time that the TDD reconfiguration should be valid. The lifetime parameter can be implemented in various ways, and can have different bit lengths.

The use of a time-to-live parameter of only 1 bit makes it possible to distinguish between two periods during which the TDD configuration must be valid; for example, 10 ms and 40 ms, that is, 1 radio frame and 4 radio frames. It appears that one radio frame will be the shortest reasonable valid time for such dynamic UL/DL TDD reconfiguration. 4 radio frames are equivalent in size to an MBSFN (Single Frequency Broadcast Network) with multicast). Of course, any time values other than 10 and 40 ms, such as 100 ms or 200 ms, can be set. 200 ms, that is, 20 radio frames, is equivalent to the RRC timeline for TDD reconfiguration. Thus, the gap between the TT reconfiguration timelines using the PHY layer (ie, DCI/CRC) and the MAC/RRC layer can be bridged without losing the opportunity for fast reconfiguration.

The use of more than 1 bit, ie 2 bits or more, for the timeout parameter naturally allows more flexible TDD reconfiguration.

Thus, the mobile station determines the amount of time that the dynamic TDD configuration indicated by said DCI/CRC should be applied.

HARQ instruction

The HARQ instruction for instructing the mobile station(s) to restart or not to restart the HARQ protocol upon applying the new TDD configuration relates to a problem caused by changing the TDD configuration, as will be explained in connection with FIG.

For purposes of illustration in FIG. 14, it is assumed that UL/DL TDD configuration #3 is applied to radio frame n and UL/DL TDD configuration #5 is applied to the next radio frame n+1. As shown, subframes 3, 4 change from uplink transmission to downlink transmission. Accordingly, the number of HARQ processes or timing for UL HARQ may change when reconfiguring UL/DL TDD subframes, as can be seen in TS 36.213 section 7 (with Table 7-1), section 8, section 8.3 (with Table 8.3-1) , and section 10, including subsections, specifically subsection 10.2. In case there are fewer HARQ processes, the UE cannot know which process is ongoing and which earlier PDCCH is the reference for periodic New Data Indicator (NDI) switching. Some of the resulting problems will be described in more detail below.

The HARQ procedure for the PDSCH received in subframes 7, 8 and 9 of radio frame n shows ambiguities. The ACK/NACK feedback for the intended PDSCH transmission in these subframes 7, 8 and 9 can no longer be performed correctly since subframes 3 and 4 of radio frame n+1 no longer allow sending a PUCCH with ACK/NACK feedback.

The HARQ parameter may configure the HARQ behavior in the mobile station by applying the UL/DL TDD reconfiguration.

The first optional possibility is that the HARQ instruction causes a complete restart of the HARQ protocol so that all subsequent transmissions are initiating a new transport block. Implicitly, the HARQ buffers are flushed, i.e. removed. The advantage is that the destruction of the HARQ buffers can be avoided.

This first optional capability may be indicated by the following procedure. The NDI for all uplink HARQ processes is set to 0. Soft (software) buffers for all downlink HARQ processes are reset. For each downlink HARQ process, the next received transmission for a transport block is considered the very first transmission.

The second optional possibility for the HARQ instruction parameter is that the HARQ protocol does not have a restart. Thus, the HARQ buffers are preserved to allow the HARQ protocol to continue throughout the UL/DL TDD reconfiguration so that the optimization is performed across the entire bandwidth. This is beneficial if most of the HARQ processes on the old TDD configuration completed successfully during the TDD reconfiguration.

Therefore, there is a compromise between the first and second optional possibilities, and the base station can set the HARQ instruction to one of two values. A 1-bit HARQ instruction field is sufficient in this preferred case.

Therefore, the mobile station determines from this parameter what the behavior is with respect to HARQ processes.

Fill field

The padding field may be inserted into the DCI with a predefined value known to the mobile station as well as the base station, and for the mobile station to determine if the padding field takes on the predefined value. If the DCI contains a padding field with a predetermined value, the mobile station can determine that the received DCI does indeed transport a UL/DL TDD reconfiguration. Therefore, the padding field allows the mobile station to secondarily determine that the DCI is transporting the UL/DL TDD configuration; not only by RNTI TDD (First Embodiment), SC-RNTI (Second Embodiment), or an invalid parameter in DCI (Third Embodiment).

The padding field is preferably included in a DCI in 3GPP Format, such as Format 1C, to use the remaining DCI bits that may not be used for any of the other parameters. The padding field may thus be 1-32 bits long. When using a DCI of a particular size, and after deciding and setting the specific additional parameters to be included in the DCI, there will often be bits left over that would not otherwise be used. Therefore, to use these bits, the padding field is also used.

The term "virtual CRC" may also be used by one of ordinary skill in the art to describe such a padding field in terms of certain bit values.

Thus, the mobile station can compare the value of the padding field with a predetermined value to ensure that the DCI carrying said padding field is indeed intended to carry dynamic TDD reconfiguration.

Buffer Status Report (BSR)

The BSR instructions from the mobile station to the base station are used to help allocate uplink resources. Typically, the more full the buffer is at the mobile station, the more resources or more frequently resources must be assigned to that mobile station for uplink transmission. Details can be found in The UMTS Long Term Evolution - From Theory to Practice, edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 4.4.2.2.

BSR reporting is a function of the MAC which implies that the corresponding transport blocks in the physical layer are subjected to a HARQ procedure with possible retransmissions. A BSR can be triggered under several circumstances, including the expiration of the 'periodicBSR' timer. Details can be found in The UMTS Long Term Evolution - From Theory to Practice, edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 4.4.2.2, incorporated by reference.

As mentioned, there may be some ambiguity or confusion between the mobile station and the base station regarding the state of the HARQ protocol upon applying the TDD reconfiguration. In the case of a BSR transmission, therefore, there may be a misunderstanding if the BSR is part of the uplink (re)transmission after the TDD reconfiguration. Therefore, the mobile station may receive a parameter to know whether the BSR procedure should be restarted, which may mean one or more of the following:

- canceling or restarting pending (re)transmissions of BSRs,

- reset/restart timer 'periodicBSR',

- reset/restart timer 'retxBSR'.

Scheduling Request (SR) and Random Access Channel (RACH) procedure

In case the mobile station intends to transmit the BSR, but there are no or insufficient uplink resources to transmit the BSR, the mobile station may transmit the SR to the base station on the PUCCH or using the RACH procedure. Details can be found in The UMTS Long Term Evolution - From Theory to Practice, edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 4.4.2.2, incorporated herein by reference. Since the timing of when PUCCH may be transmitted for a received PDSCH transmission is generally affected by TDD reconfiguration as shown in FIG. 14, and the RACH procedure may go out of the radio frame, i. DL and UL transmission opportunities to complete the entire RACH procedure, it may be more error-safe to tell the MS that it should cancel or restart the SR and/or RACH procedure again after applying the new TDD configuration.

Generating a Power Headroom Report (PHR)

Like the BSR, the PHR is used to control the uplink transmit power for the mobile station. The base station may use the PHR to determine how much more uplink bandwidth per subframe the mobile station is able to use. Details can be found in The UMTS Long Term Evolution - From Theory to Practice, edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 18.3.3, incorporated herein by reference.

Since the available uplink transmit power per subframe must be distributed over the entire uplink assigned bandwidth, this is equivalent to a power headroom report. The PHR is triggered, for example, when a significant change in the estimated path loss has been detected since the last PHR, or when a configured time has elapsed since the previous PHR ('PHR Inhibit Timer'), or when more TPC commands have been issued by the MS than set in the configuration.

Like the BSR, the PHR is transmitted as MAC information in the assigned uplink resources, and hence the procedure may be affected by TDD reconfiguration. Therefore, the additional parameter may tell the mobile station to do one or more of the following upon TDD reconfiguration:

- cancel a pending PHR report,

- initiate a new PHR report,

- reset/restart the PHR inhibit timer,

- reset the TPC command counter or set it to the specified value.

Hardware and software implementation of the invention

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

It is further recognized 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 by a combination of these devices.

In addition, various embodiments of the invention could also be implemented by software modules that are executed by a processor, or directly by hardware. In addition, a combination of software modules and hardware implementation is possible. Program modules may be stored on any form of computer-readable media, such as random access memory (RAM), erasable programmable ROM (EPROM), electrically-erasable programmable ROM (EEPROM), flash memory, registers, hard disk drives, ROM to CD. disc (CD-ROM), digital multifunction disc (DVD), etc.

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

A person skilled in the art should understand that numerous changes and/or modifications can be made with respect to this invention, as shown in specific embodiments, without departing from the essence and scope of the invention, as described in general terms. The present embodiments, therefore, are to be considered in all respects illustrative and non-restrictive.

Claims (55)

1. An integrated circuit that, in operation, controls processing in a mobile station operating in one of a plurality of time division duplex (TDD) communication configurations in a communication system, the processing including: receiving a system information block (SIB) that includes a default TDD configuration defining uplink, downlink, and special subframes in one or more radio frames, each radio frame including a plurality of subframes, receiving downlink control information and a corresponding error detection code for the downlink control information, wherein the error detection code is scrambled with an identifier associated with the mobile station, in response to successful decoding of the downlink control information with the error detection code scrambled with said identifier, a TDD configuration is determined from a plurality of TDD configurations including a default TDD configuration based on the downlink control information, the downlink control information identifying a TDD configuration among a plurality of TDD configurations, determining at least one serving cell to which said defined TDD configuration is to be applied, applying said determined TDD configuration to one or more radio frames n+1 to n+x in said at least one serving cell, where n corresponds to a radio frame in which downlink control information and an error detection code are received by the mobile station, and in response to the expiration of said defined TDD configuration, apply the default TDD configuration to radio frame n+1+x, where x is a positive integer and x is 1, 2 or 4 and x is a predefined and fixed amount of time until the configuration is applied TDD by default. 2. The integrated circuit according to claim 1, wherein the communication system is an LTE communication system and the downlink control information is downlink control information in 1C format. 3. The integrated circuit according to any one of claims 1, 2, wherein the downlink control information includes an invalid parameter with one of the plurality of invalid values, and one of the plurality of TDD configurations is indicated by one or more of the invalid values, wherein one or several of the invalid values indicate at least one of the following: specified TDD configuration, a HARQ instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the mobile station for the serving cell to which the specified TDD configuration is applied, a valid time parameter indicating the amount of time during which the specified TDD configuration should be applied, a buffer status report procedure instruction that causes the current buffer status report procedure to be canceled or a new buffer status report procedure to be initiated, upon application of the specified TDD configuration, a scheduling request procedure instruction to cancel the current scheduling request procedure or to initiate a new scheduling request procedure upon applying the specified TDD configuration, a random channel access procedure instruction causing the current random channel access procedure to be canceled or a new random channel access procedure to be initiated upon applying the specified TDD configuration, and a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration. 4. An integrated circuit according to any one of claims 1 to 3, wherein the downlink control information indicates at least one of the following: the TDD configuration to be applied to said at least one serving cell, in the TDD configuration field, a HARQ instruction including an instruction to restart or not to restart the HARQ protocol of a mobile station for a serving cell to which said specific TDD configuration is applied upon application of said specific TDD configuration, a validity time parameter for said specific TDD configuration indicating the amount of time during which said specific TDD configuration should be applied, the bit value of the padding field, which is or is not identical to the predefined bit value, a buffer status report procedure instruction that causes the current buffer status report procedure to be canceled or a new buffer status report procedure to be initiated, upon application of said specific TDD configuration, a scheduling request procedure instruction instructing to cancel the current scheduling request procedure or initiate a new scheduling request procedure by applying said specific TDD configuration, a random channel access procedure instruction causing the current random channel access procedure to be canceled or a new random channel access procedure to be initiated by applying said specific TDD configuration, and a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying said specific TDD configuration. 5. Base station, containing: a transmitter that, in operation, transmits to a user equipment operating in one of a plurality of time division duplex (TDD) configurations in a communication system, a system information block (SIB) that includes a default TDD configuration defining uplink subframes, downlink and specific subframes in one or more radio frames, each radio frame including a plurality of subframes; and a processing circuit that is connected to the transmitter and that, in operation, generates downlink control information and a corresponding error detection code for the downlink control information, wherein the downlink control information indicates a TDD configuration from a plurality of TDD configurations, including a TDD configuration of by default, and the error detection code is scrambled with an identifier associated with the user equipment; wherein the transmitter, in operation, transmits the generated downlink control information and the error detection code to the user equipment; and while the processing scheme in operation, applies the specified TDD configuration to an n+1 radio frame in at least one serving cell, where n corresponds to a radio frame in which downlink control information and an error detection code are transmitted by the base station, and in response to the expiration of the specified TDD configuration, applies the default TDD configuration to radio frame n+1+x, where x is a positive integer. 6. The base station of claim 5, wherein x is 1, 2, or 4. 7. The base station according to claim 5, wherein the communication system is an LTE communication system and the downlink control information is downlink control information in 1C format. 8. The base station of claim 5, wherein the downlink control information indicates at least one of the following: the TDD configuration to be applied to said at least one serving cell, in the TDD configuration field, a HARQ instruction including an instruction to, upon applying the specified TDD configuration, restart or not restart the HARQ protocol of the user equipment for at least one serving cell to which the specified TDD configuration is applied, a valid time parameter for the specified TDD configuration indicating the amount of time during which the specified TDD configuration should be applied, the bit value of the padding field, which is or is not identical to the predefined bit value, a buffer status report procedure instruction that causes the current buffer status report procedure to be canceled or a new buffer status report procedure to be initiated, upon application of the specified TDD configuration, a scheduling request procedure instruction to cancel the current scheduling request procedure or to initiate a new scheduling request procedure upon applying the specified TDD configuration, a random channel access procedure instruction causing the current random channel access procedure to be canceled or a new random channel access procedure to be initiated upon applying the specified TDD configuration, and a power headroom reporting instruction for canceling the current power headroom reporting or initiating a new power headroom reporting by applying the specified TDD configuration. 9. A method performed by a base station, the method including: transmitting to a user equipment operating in one of a plurality of time division duplex (TDD) configurations in a communication system a system information block (SIB) that includes a default TDD configuration specifying uplink, downlink subframes, and special subframes in one or more radio frames, each radio frame including a plurality of subframes; generating downlink control information and a corresponding error detection code for the downlink control information, wherein the downlink control information indicates a TDD configuration from a plurality of TDD configurations including a default TDD configuration, and the error detection code is scrambled with an identifier associated with user equipment; transmitting the generated downlink control information and the error detection code to the user equipment; applying said TDD configuration to radio frame n+1 in at least one serving cell, where n corresponds to a radio frame in which downlink control information and an error detection code are transmitted by the base station, and in response to the expiration of the specified TDD configuration, apply the default TDD configuration to radio frame n+1+x, where x is a positive integer. 10. An integrated circuit that, in operation, controls processing in a base station, the processing including the steps of: transmitting to a user equipment operating in one of a plurality of time division duplex (TDD) configurations in a communication system a system information block (SIB) that includes a default TDD configuration specifying uplink, downlink subframes, and special subframes in one or more radio frames, each radio frame including a plurality of subframes; generating downlink control information and a corresponding error detection code for the downlink control information, wherein the downlink control information indicates a TDD configuration from a plurality of TDD configurations including a default TDD configuration, and the error detection code is scrambled with an identifier associated with user equipment; transmitting the generated downlink control information and the error detection code to the user equipment; applying said TDD configuration to radio frame n+1 in at least one serving cell, where n corresponds to a radio frame in which downlink control information and an error detection code are transmitted by the base station, and in response to the expiration of the specified TDD configuration, apply the default TDD configuration to radio frame n+1+x, where x is a positive integer.

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