JP2014220667A - Terminal device, base station device, communication system, communication method, and integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide techniques related to a terminal device, base station device, communication system, communication method, and an integrated circuit that achieve an efficient random access procedure in a plurality of cells.SOLUTION: In a communication system in which a terminal device and a plurality of base station devices are connected by use of a plurality of cells, the base station device of a second cell receives, from the base station device of a first cell, transmission timing adjustment information based on a physical random access channel transmitted from the terminal device to the first cell, and notifies the base station device of the first cell of information indicating whether a response to the physical random access channel could be transmitted or not in a section where the response to the random access channel is received preset in the terminal device.

Description

  The present invention relates to a terminal device, a base station device, a communication system, a communication method, and an integrated circuit, and more particularly to a random access processing technique in a communication system that requires random access processing for each of different base station devices.

  Evolved which realized high-speed communication by adopting OFDM (Orthogonal Frequency-Division Multiplexing) communication method and flexible scheduling of predetermined frequency and time unit called resource block in 3GPP (3rd Generation Partnership Project) which is a standardization project The standardization of Universal Terrestrial Radio Access (hereinafter referred to as EUTRA) was carried out.

  Further, 3GPP is studying Advanced EUTRA that realizes higher-speed data transmission and has upward compatibility with EUTRA. In EUTRA, a communication system is premised on a network in which base station apparatuses have substantially the same cell configuration (cell size). However, in Advanced EUTRA, base station apparatuses (cells) having different configurations are mixed in the same area. Communication systems based on existing networks (heterogeneous wireless networks, heterogeneous networks) are being studied.

  In a communication system in which a cell having a large cell radius (macro cell) and a cell having a cell radius smaller than the macro cell (small cell, small cell) are arranged as in a heterogeneous network, the terminal device includes a macro cell and a small cell. (Dual Connectivity (dual connectivity, dual connectivity)) is being studied (Non-Patent Document 1).

  In Non-Patent Document 1, when a terminal device tries to realize dual connectivity between a cell (macro cell) having a large cell radius (cell size) and a cell (small cell (or pico cell)) having a small cell radius, The network on the assumption that the backbone line (Backhaul) between the small cell and the small cell is low speed and delay occurs. That is, the delay of the exchange of control information or user information between the macro cell and the small cell may make it impossible or impossible to realize a function that could be realized in the past.

  Further, in Non-Patent Document 2, when a terminal device is connected to a plurality of cells simultaneously, a response of a physical random access channel (random access response) transmitted in the uplink of a certain cell is a specific cell or physical random access channel. Has been proposed to be received by the cell that transmitted.

R2-183045, NTT DOCOMO, INC. (Rapporture), 3GPP TSG RAN2 # 81, St. Julian's, Malta, January 28th-February 1st, 2013. http: // www. 3 gpp. org / ftp / tsg_ran / WG2_RL2 / TSGR2_81 / Docs / R2-121635, InterDigital Communications, 3GPP TSG RAN2 # 77bis, Jeju, Korea, March 26th-30th, 2012 http: // www. 3 gpp. org / ftp / tsg_ran / WG2_RL2 / TSGR2_77bis / Docs /

  As in the example of Non-Patent Document 2, when a terminal device transmits a physical random access channel to uplinks of a plurality of cells, a base station device transmits a random access response in a specific cell (for example, a macro cell). In order to achieve this, it is indispensable that the system does not cause a delay in the backbone line.

  That is, when different base station apparatuses are connected by dual connectivity, and when the base station apparatus that receives the physical random access channel and the base station apparatus that transmits the random access response are different, random access than before is performed. Although it takes time until the response is transmitted, the terminal device does not consider whether there is a delay in the backbone line between the base station devices, and therefore determines that reception of the random access response has failed. There's a problem.

  Further, as described above, when the base station apparatus that receives the physical random access channel is different from the base station apparatus that transmits the random access response, the presence or absence of the delay of the backbone line between the base station apparatuses is not considered. The base station device that receives the random access channel may determine whether the cause when the terminal device fails to receive the random access response and retransmits the physical random access channel is due to the influence of the radio situation. There is a problem in that it may not be possible to determine whether it is due to an influence and random access processing based on an inappropriate parameter may be continued.

  In view of the above problems, an object of an embodiment of the present invention is to provide a terminal device and a base station device that realize optimization of random access processing in a communication system that requires random access processing for each of different base station devices. An object of the present invention is to provide a technology related to a communication system, a communication method, and an integrated circuit.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the terminal device of the present invention is a terminal device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells, and is a physical random access channel transmitted to the first cell. Is received from the second cell, and information related to the time required to receive the response to the transmitted physical random access channel is transmitted to the base station apparatus.

  (2) Moreover, the base station apparatus of the present invention is a base station apparatus in a communication system in which a terminal apparatus and a plurality of base station apparatuses are connected using a plurality of cells, from the terminal apparatus to the first cell. Whether or not the transmission timing adjustment information based on the physical random access channel transmitted to the terminal device is received, and the response of the physical random access channel can be transmitted to the terminal device in the section for receiving the response of the random access channel set in the terminal device in advance Information indicating this is notified to the base station apparatus of the first cell.

  (3) Further, in the base station apparatus of the present invention, the information indicating whether or not the transmission is possible includes an identifier indicating which of the transmission timing adjustment information corresponds to.

  (4) Moreover, the communication system of this invention is a communication system by which a terminal device and a several base station apparatus are connected using a some cell, Comprising: A terminal device is a physical random with respect to a 1st cell. The access channel is transmitted, the response to the physical random access channel is received from the second cell, and the information related to the time required to receive the response from the transmission of the physical random access channel is obtained from the base station apparatus of the first cell or the second cell The base station apparatus of the first cell transmits transmission timing adjustment information based on the physical random access channel transmitted from the terminal apparatus to the first cell. It transmits to a base station apparatus, The base station apparatus of a 2nd cell transmits transmission timing adjustment information to a terminal device by a 2nd cell, It is characterized by the above-mentioned.

  (5) Moreover, the communication method of this invention is a communication method of the terminal device in the communication system with which a terminal device and a some base station apparatus are connected using a some cell, Comprising: With respect to a 1st cell, Receiving a response to the transmitted physical random access channel from the second cell, and transmitting to the base station apparatus information about a time required for receiving the response from transmission to the transmitted physical random access channel. It is provided with at least.

  (6) Moreover, the communication method of the present invention is a communication method for a base station apparatus in a communication system in which a terminal apparatus and a plurality of base station apparatuses are connected using a plurality of cells. Whether the response of the physical random access channel was transmitted in the step of receiving the transmission timing adjustment information based on the physical random access channel transmitted to the cell and the period of receiving the response of the random access channel preset in the terminal device And a step of notifying the base station apparatus of the first cell of information indicating whether or not.

  (7) In the communication method of the present invention, the information indicating whether or not the transmission is possible includes an identifier indicating which transmission timing adjustment information corresponds to the information.

  (8) An integrated circuit according to the present invention is an integrated circuit mounted on a terminal device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells, wherein the first cell A function of receiving a response to the physical random access channel transmitted from the second cell, and a function of transmitting to the base station apparatus information relating to the time required for receiving the response from the transmission of the transmitted physical random access channel And a terminal device having a series of functions including

  (9) An integrated circuit according to the present invention is an integrated circuit mounted on a base station device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells. A function of receiving transmission timing adjustment information based on the physical random access channel transmitted to the first cell, and a response of the physical random access channel in a period of receiving a response of the random access channel preset in the terminal device The base station apparatus is caused to exhibit a series of functions including a function of notifying the base station apparatus of the first cell of information indicating whether or not transmission is possible.

  (10) Further, in the integrated circuit of the present invention, the information indicating whether or not the transmission is possible includes an identifier indicating which transmission timing adjustment information corresponds to the information.

  The present specification relates to a terminal device, a base station device, a communication system, a communication method, and an integrated circuit that realize optimization of random access processing in a communication system that requires random access processing for each of different base station devices. In this regard, each embodiment is disclosed, but a communication method applicable to each embodiment is not limited to a communication method that is upward compatible with EUTRA, such as EUTRA or Advanced EUTRA.

  For example, the techniques described herein include code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), And can be used in various communication systems using other access schemes and the like. Further, in this specification, a system and a network can be used synonymously.

  According to the embodiments of the present invention, a terminal device, a base station device, a communication system, a measurement method, and an integration capable of performing efficient communication by optimization of random access processing based on information on delay of random access processing A technique related to a circuit can be provided.

It is a block diagram which shows an example of schematic structure of the terminal device which concerns on embodiment of this invention. It is a block diagram which shows an example of schematic structure of the base station apparatus which concerns on embodiment of this invention. It is the figure which showed an example of the random access procedure in the 1st Embodiment of this invention. It is the figure which showed an example of the random access procedure in the 3rd Embodiment of this invention. It is a figure which shows an example of the architecture of dual connectivity which concerns on embodiment of this invention. It is a figure which shows another example of the architecture of dual connectivity which concerns on embodiment of this invention. It is a sequence chart figure for demonstrating a Contention based Random Access procedure. It is a sequence chart figure for demonstrating a Non Contention based Random Access procedure.

  A technique related to each embodiment of the present invention will be briefly described below.

[Physical channel / Physical signal]
The main physical channels and physical signals used in EUTRA and Advanced EUTRA will be described. A channel means a medium used for signal transmission, and a physical channel means a physical medium used for signal transmission. In the present invention, a physical channel can be used synonymously with a signal. The physical channel may be added in the future in EUTRA and Advanced EUTRA, or the structure and format of the physical channel may be changed or added. However, even if changed or added, the description of each embodiment of the present invention is provided. It does not affect.

  In EUTRA and Advanced EUTRA, scheduling of physical channels or physical signals is managed using radio frames. One radio frame is 10 ms, and one radio frame is composed of 10 subframes. Further, one subframe is composed of two slots (that is, one subframe is 1 ms, and one slot is 0.5 ms). Also, resource blocks are used as a minimum scheduling unit in which physical channels are allocated. A resource block is defined by a constant frequency region composed of a set of a plurality of subcarriers (for example, 12 subcarriers) and a region composed of a constant transmission time interval (1 slot) on the frequency axis.

  Synchronization signals (Synchronization Signals) are composed of three types of primary synchronization signals and secondary synchronization signals composed of 31 types of codes arranged alternately in the frequency domain. Depending on the combination, 504 cell identifiers (Physical Cell Identity (PCI)) for identifying the base station apparatus and frame timing for radio synchronization are shown. The terminal device specifies the physical cell ID of the synchronization signal received by the cell search.

  A physical broadcast information channel (PBCH; Physical Broadcast Channel) is transmitted for the purpose of notifying (setting) control parameters (broadcast information (system information): System information) that are commonly used by terminal devices in a cell. The broadcast information that is not notified in the physical broadcast information channel is notified to the terminal device in the cell of the radio resource in which the broadcast information is transmitted in the physical downlink control channel, and the physical downlink shared channel in the notified radio resource. A layer 3 message (system information) for notifying broadcast information is transmitted.

  As broadcast information, a cell global identifier (CGI) indicating a cell-specific identifier, a tracking area identifier (TAI) for managing a standby area by paging, random access setting information (such as a transmission timing timer), Common radio resource setting information, neighboring cell information, uplink access restriction information, etc. in the cell are notified.

  The downlink reference signal is classified into a plurality of types according to its use. For example, cell-specific reference signals (RS) are pilot signals transmitted at a predetermined power for each cell, and are downlink reference signals that are periodically repeated in the frequency domain and the time domain based on a predetermined rule. It is. The terminal device measures the reception quality for each cell by receiving the cell-specific RS. The terminal apparatus also uses the downlink cell-specific RS as a reference signal for demodulating the physical downlink control channel or physical downlink shared channel transmitted simultaneously with the cell-specific RS. As a sequence used for the cell-specific RS, a sequence that can be identified for each cell is used.

  The downlink reference signal is also used for estimation of downlink propagation path fluctuations. A downlink reference signal used for estimation of propagation path fluctuation is referred to as a channel state information reference signal (CSI-RS). Also, the downlink reference signal set individually for the terminal device is called UE specific reference signals (URS) or Dedicated RS (DRS), and demodulates the physical downlink control channel or the physical downlink shared channel. This is referred to for the channel propagation compensation process.

  A physical downlink control channel (PDCCH) is transmitted by several OFDM symbols (for example, 1 to 4 OFDM symbols) from the head of each subframe. An enhanced physical downlink control channel (EPDCCH) is a physical downlink control channel arranged in an OFDM symbol in which the physical downlink shared channel PDSCH is arranged. The PDCCH or EPDCCH is used for the purpose of notifying the terminal device of radio resource allocation information according to the scheduling of the base station device and information for instructing an adjustment amount of increase / decrease of transmission power. Hereinafter, when simply referred to as a physical downlink control channel (PDCCH), it means both physical channels of PDCCH and EPDCCH unless otherwise specified.

  Before transmitting / receiving layer 3 messages (paging, handover command, etc.) that are downlink data and downlink control data, the terminal apparatus monitors (monitors) the physical downlink control channel addressed to itself and By receiving the physical downlink control channel, it is necessary to acquire radio resource allocation information called an uplink grant during transmission and a downlink grant (downlink assignment) during reception from the physical downlink control channel. In addition, the physical downlink control channel may be configured to be transmitted in the area of the resource block that is assigned individually (dedicated) from the base station apparatus to the terminal apparatus, in addition to being transmitted by the OFDM symbol described above. Is possible.

  The physical uplink control channel (PUCCH) is a reception confirmation response (ACK / NACK; Acknowledgement / Negative Acknowledgment) or downlink propagation path (channel state) information transmitted on the physical downlink shared channel. (CSI; Channel State Information), used for uplink radio resource allocation request (radio resource request, scheduling request (SR)).

  CSI includes CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), PTI (Precoding Type Indicator), and RI (Rank Indicator). Each indicator may be used under the name “Indication”.

  The Physical Downlink Shared Channel (PDSCH) is used to notify the terminal apparatus as broadcast data (system information) not notified by the paging or physical broadcast information channel as a layer 3 message in addition to the downlink data. Is done. The radio resource allocation information of the physical downlink shared channel is indicated by the physical downlink control channel. The physical downlink shared channel is transmitted after being arranged in an OFDM symbol other than the OFDM symbol through which the physical downlink control channel is transmitted. That is, the physical downlink shared channel and the physical downlink control channel are time division multiplexed within one subframe.

  A physical uplink shared channel (PUSCH) mainly transmits uplink data and uplink control data, and can also include control data such as downlink reception quality and ACK / NACK. In addition to uplink data, uplink control information is also used to notify the base station apparatus from the terminal apparatus as a layer 3 message. Similarly to the downlink, the radio resource allocation information of the physical uplink shared channel is indicated by the physical downlink control channel.

  The uplink reference signal (uplink reference signal; uplink pilot signal, also referred to as uplink pilot channel) is transmitted from the base station apparatus to the physical uplink control channel PUCCH and / or the physical uplink shared channel PUSCH. A demodulation reference signal (DMRS) used for demodulation and a sounding reference signal (SRS) used mainly by the base station apparatus to estimate an uplink channel state are included. It is. The sounding reference signal includes a periodic sounding reference signal (Periodic SRS) transmitted periodically and an aperiodic sounding reference signal (Aperiodic SRS) transmitted when instructed by the base station apparatus. .

  A physical random access channel (PRACH) is a channel used for reporting (setting) a preamble sequence and has a guard time. The preamble sequence is configured to notify information to the base station apparatus by a plurality of sequences. For example, when 64 types of sequences are prepared, 6-bit information can be indicated to the base station apparatus. The physical random access channel is used as an access means for the terminal device to the base station device.

  The terminal apparatus transmits transmission timing adjustment information (timing advance (for timing uplink ()) required for an uplink radio resource request when the physical uplink control channel is not set, or for matching the uplink transmission timing with the reception timing window of the base station apparatus. The physical random access channel is used for requesting the base station apparatus (also called Timing Advance; TA). Also, the base station apparatus can request the terminal apparatus to start a random access procedure using the physical downlink control channel.

  The layer 3 message is a message handled by a control plane (CP (Control-plane, C-Plane)) protocol exchanged between the terminal device and the RRC (Radio Resource Control) layer between the base station device and the RRC signaling or RRC. Can be used interchangeably with message. A protocol for handling user data with respect to the control plane is referred to as a user plane (UP (User-plane, U-Plane)). Since other physical channels are not related to each embodiment of the present invention, detailed description thereof is omitted.

[Wireless network]
The communicable range (communication area) of each frequency controlled by the base station apparatus is regarded as a cell. At this time, the communication area covered by the base station apparatus may have a different width and a different shape for each frequency. Moreover, the area to cover may differ for every frequency. A wireless network in which cells having different types of base station apparatuses and different cell radii are mixed in areas of the same frequency or different frequencies to form one communication system is referred to as a heterogeneous network.

  The terminal device operates by regarding the inside of the cell as a communication area. When a terminal device moves from one cell to another cell, it moves to another appropriate cell by a cell reselection procedure during non-wireless connection (during non-communication) and by a handover procedure during wireless connection (during communication). To do. An appropriate cell is a cell that is generally determined that access by a terminal device is not prohibited based on information specified by a base station device, and the downlink reception quality satisfies a predetermined condition. Indicates the cell to be used.

  Also, the terminal device and the base station device aggregate (aggregate) frequencies (component carriers or frequency bands) of a plurality of different frequency bands (frequency bands) by carrier aggregation into one frequency (frequency band). You may apply the technique handled like. Component carriers include uplink component carriers corresponding to the uplink and downlink component carriers corresponding to the downlink. In this specification, a frequency and a frequency band may be used synonymously.

  For example, when five component carriers having a frequency bandwidth of 20 MHz are aggregated by carrier aggregation, a terminal device capable of carrier aggregation regards these as a frequency bandwidth of 100 MHz and performs transmission / reception. The component carriers to be aggregated may be continuous frequencies, or may be frequencies at which all or part of them are discontinuous. For example, when the usable frequency band is 800 MHz band, 2 GHz band, and 3.5 GHz band, one component carrier is transmitted in the 800 MHz band, another component carrier is transmitted in the 2 GHz band, and another component carrier is transmitted in the 3.5 GHz band. It may be.

  It is also possible to aggregate a plurality of continuous or discontinuous component carriers in the same frequency band. The frequency bandwidth of each component carrier may be a frequency bandwidth (for example, 5 MHz or 10 MHz) narrower than the receivable frequency bandwidth (for example, 20 MHz) of the terminal device, and the aggregated frequency bandwidth may be different from each other. . The frequency bandwidth is preferably equal to one of the frequency bandwidths of the conventional cell in consideration of backward compatibility, but may be a frequency bandwidth different from that of the conventional cell.

  In addition, component carriers (carrier types) that are not backward compatible may be aggregated. Note that the number of uplink component carriers assigned (set or added) to the terminal device by the base station device is preferably equal to or less than the number of downlink component carriers.

  A cell composed of an uplink component carrier in which an uplink control channel is set for a radio resource request and a downlink component carrier that is cell-specifically connected to the uplink component carrier is a primary cell (PCell: Primary cell). ). Moreover, the cell comprised from component carriers other than a primary cell is called a secondary cell (SCell: Secondary cell). The terminal device performs reception of a paging message in the primary cell, detection of update of broadcast information, initial access procedure, setting of security information, and the like, but may not perform these in the secondary cell.

  The primary cell is not subject to activation and deactivation control (that is, it is always considered to be activated), but the secondary cell is in a state of activation and deactivation. These state changes are explicitly specified from the base station apparatus, and the state is changed based on a timer set in the terminal apparatus for each component carrier. The primary cell and the secondary cell are collectively referred to as a serving cell.

  Note that carrier aggregation is communication performed by a plurality of cells using a plurality of component carriers (frequency bands), and is also referred to as cell aggregation. The terminal device may be wirelessly connected to the base station device via a relay station device (or repeater) for each frequency. That is, the base station apparatus of each embodiment of the present invention can be replaced with a relay station apparatus.

  The base station apparatus manages a cell, which is an area in which the terminal apparatus can communicate with the base station apparatus, for each frequency. One base station apparatus may manage a plurality of cells. The cells are classified into a plurality of types according to the size (cell size) of the area communicable with the terminal device. For example, the cell is classified into a macro cell and a small cell. Further, small cells are classified into femtocells, picocells, and nanocells according to the size of the area. In addition, when a terminal device can communicate with a certain base station device, a cell set to be used for communication with the terminal device among the cells of the base station device is a serving cell. A cell that is not used for other communication is called a neighbor cell.

[Dual Connectivity]
The basic structure (architecture) of dual connectivity will be described with reference to FIGS. 5 and 6 show that the terminal device 1 is simultaneously connected to a plurality of base station devices 2 (indicated by the base station device 2-1 and the base station device 2-2 in the figure). The base station apparatus 2-1 is a base station apparatus that constitutes a macro cell, and the base station apparatus 2-2 is a base station apparatus that constitutes a small cell. As described above, the simultaneous connection of the terminal device 1 using cells belonging to the plurality of base station devices 2 is referred to as dual connectivity. Each base station apparatus 2 may be operated at the same frequency or may be operated at different frequencies.

  Note that carrier aggregation is different from dual connectivity in that a plurality of cells are managed by one base station apparatus 2 and the frequency of each cell is different. In other words, carrier aggregation is a technology that connects one terminal device 1 and one base station device 2 via a plurality of cells, whereas dual connectivity is a technology that connects one terminal device 1 and a plurality of terminals. This is a technology for connecting the base station apparatus 2 via a plurality of cells.

  The terminal device 1 and the base station device 2 can apply a technique applied to carrier aggregation to dual connectivity. For example, the terminal apparatus 1 and the base station apparatus 2 may provide techniques such as allocation of primary cells and secondary cells, activation / deactivation, and the like for cells connected by dual connectivity.

  5 and 6, the base station apparatus 2-1 or the base station apparatus 2-2 is connected to the MME 300 and the SGW 400 via a backbone line. The MME 300 is a higher-level control station apparatus corresponding to MME (Mobility Management Entity), and plays a role of setting mobility of the terminal apparatus 1 and authentication control (security control) and a route of user data to the base station apparatus 2. Have. The SGW 400 is a higher-level control station device corresponding to Serving Gateway (S-GW), and has a role of transmitting user data according to a user data path to the terminal device 1 set by the MME 300.

  5 and 6, the connection path between the base station apparatus 2-1 or the base station apparatus 2-2 and the SGW 400 is referred to as an SGW interface N10. Further, the connection path between the base station apparatus 2-1 or the base station apparatus 2-2 and the MME 300 is referred to as an MME interface N20. The connection path between the base station device 2-1 and the base station device 2-2 is referred to as a base station interface N30. The SGW interface N10 is also referred to as an S1-U interface in EUTRA. The MME interface N20 is also referred to as an S1-MME interface in EUTRA. The base station interface N30 is also referred to as an X2 interface in EUTRA.

  As an architecture for realizing dual connectivity, a configuration as shown in FIG. 5 can be adopted. In FIG. 5, the base station apparatus 2-1 and the MME 300 are connected by an MME interface N20. Moreover, the base station apparatus 2-1 and the SGW 400 are connected by an SGW interface N10. Further, the base station device 2-1 provides a communication path with the MME 300 and / or the SGW 400 to the base station device 2-2 via the base station interface N30. In other words, the base station device 2-2 is connected to the MME 300 and / or the SGW 400 via the base station device 2-1.

  Further, as another architecture for realizing dual connectivity, a configuration as shown in FIG. 6 can be adopted. In FIG. 6, the base station apparatus 2-1 and the MME 300 are connected by an MME interface N20. Moreover, the base station apparatus 2-1 and the SGW 400 are connected by an SGW interface N10. The base station apparatus 2-1 provides a communication path with the MME 300 to the base station apparatus 2-2 via the base station interface N30. In other words, the base station apparatus 2-2 is connected to the MME 300 via the base station apparatus 2-1. Moreover, the base station apparatus 2-2 is connected to the SGW 400 via the SGW interface N10.

  The base station device 2-2 and the MME 300 may be directly connected by the MME interface N20.

[Random access procedure]
A series of procedures relating to random access is referred to as a random access procedure. The random access procedure includes two procedures, a Contention based Random Access (contention based random access) procedure and a Non-contention based Random Access (non-contention based random access) procedure.

  Parameters required for the random access procedure (random access setting information) include preamble group information, message size information, random access response window size information, maximum preamble retransmission count information, contention resolution timer information, backoff information, etc. . These parameters are reported from the base station apparatus to the terminal apparatus using broadcast information or individual RRC messages before the terminal apparatus starts the random access procedure.

  The Contention based Random Access procedure is a random access procedure in which preamble sequences transmitted by different terminal devices may collide (contention), and initial access from a state in which the terminal device is not connected (communication) with the base station device. And for scheduling requests for requesting uplink transmission resources from a state in which the terminal apparatus is connected to the base station apparatus. The collision of preamble sequences means that a plurality of terminal apparatuses transmit the physical random access channel using the same preamble sequence using the same frequency / time resource. Note that a preamble sequence collision is also referred to as a random access collision.

  Non-contention based Random Access procedure is a random access procedure in which no collision occurs in preamble sequences transmitted by different terminal devices, and is started by an instruction from the base station device while the terminal device is connected to the base station device. The In the Non-contention based Random Access procedure, the start of the procedure is instructed by an RRC (Radio Resource Control: Layer 3) layer message and control data of the physical downlink control channel PDCCH.

  The preamble sequence (dedicated preamble) used in the Non-contention based Random Access procedure is individually notified from the base station apparatus to the terminal apparatus. The preamble sequence used in the Contention based Random Access procedure is selected and used by the terminal device at random during random access from the preamble sequences that are not used as individual preambles. In a certain cell, the base station apparatus determines the number of preamble sequences that can be used by the terminal device for the Contention based Random Access procedure and the Non-contention based Random Access procedure, and is notified to the terminal device as preamble group information.

  The Contention based Random Access procedure will be briefly described with reference to FIG. First, the terminal device 1 selects a preamble sequence (random access preamble) based on the downlink radio channel loss (path loss) and the size of the message 3 (message transmitted in step S3) (message size information). Then, the terminal device 1 transmits the selected preamble sequence to the base station device 2 using the physical random access channel radio resource set by the base station device 2 (step S1).

  The base station apparatus 2 that has received the random access preamble calculates a transmission timing shift amount between the terminal apparatus 1 and the base station apparatus 2 from the random access preamble, and transmits a response to the random access preamble (random access response) as a transmission timing. The transmission timing adjustment information for adjusting the deviation is transmitted to the terminal device 1 (step S2).

  The terminal device 1 confirms the contents of the random access response, and adjusts the uplink transmission timing using the corresponding transmission timing adjustment information when the preamble number corresponding to the transmitted random access preamble is included in the random access response. To do. The terminal device 1 that has received the transmission timing adjustment information sets the effective time of the transmission timing adjustment information that is commonly set for the terminal device 1 in the cell by the broadcast information (or set individually in the layer 3 message). The timing of the transmission timing timer (TA timer; TAT) shown is started.

  The terminal device 1 sets the cell (cell group) in the transmission timing adjustment state during the effective time (during time) of the transmission timing timer and the transmission timing non-adjustment state (transmission timing unadjusted state) outside the effective period (stopped) Manage link status.

  Also, the terminal device 1 transmits an upper layer message (upper layer message, RRC message) to the base station device 2 based on the scheduling information included in the random access response (step S3). At this time, the terminal device 1 starts measuring the timer (contention resolution timer) indicated by the contention resolution timer information. When the base station apparatus 2 receives the upper layer message transmitted in step S3, the base station apparatus 2 transmits a collision confirmation message (contention resolution) to the terminal apparatus 1 that transmitted the upper layer message. (Step S4), the procedure is completed.

  When the contention resolution timer expires without receiving the collision confirmation message, the terminal device 1 regards that the contention resolution has failed, increments the number of preamble retransmissions, and performs backoff based on backoff information After the elapse of time, the process returns to step S1.

  The non-contention based Random Access procedure will be briefly described with reference to FIG. First, the base station apparatus 2 notifies the terminal apparatus 1 of the dedicated preamble number and the physical random access channel number (random access channel number) to be used (random access preamble allocation) (step S11). The random access channel number is a number indicating a subframe that permits transmission of the physical random access channel using the dedicated preamble (number) notified from the base station apparatus 2 to the terminal apparatus 1. For example, one random access channel number indicates that a physical random access channel may be transmitted in all subframes, and another random access channel number transmits a physical random access channel every two subframes in the time direction. It is also good.

  Random access preamble allocation is notified from the base station apparatus 2 to the terminal apparatus 1 using the physical downlink control channel PDCCH or RRC message.

  The terminal device 1 wirelessly transmits a preamble sequence (dedicated preamble) corresponding to a designated (allocated) preamble number for a physical random access channel that is permitted to transmit the dedicated preamble indicated by the random access channel number. It transmits to the base station apparatus 2 using a resource (step S12). The base station apparatus 2 that has received the dedicated preamble calculates a transmission timing shift amount between the terminal apparatus 1 and the base station apparatus 2 from the dedicated preamble, and sets a transmission timing shift in a response to the dedicated preamble (random access response). The transmission timing adjustment information for adjustment is transmitted to the terminal device 1 (step S13), and the procedure is completed.

  However, when the value of the preamble number notified from the base station apparatus 2 indicates a specific value (for example, zero), the terminal apparatus 1 performs the Contention based Random Access procedure instead of the Non-contention based Random Access procedure. In this case, the terminal device 1 completes the random access procedure according to the procedure of steps S1 to S4 in FIG.

  Here, the random access response (step S2 in FIG. 7 and step S13 in FIG. 8) from the base station apparatus 2 is transmitted in the downlink of the primary cell. That is, regardless of whether the terminal device 1 transmits the physical random access channel in the primary cell or the physical random access channel is transmitted in the secondary cell, the terminal device 1 transmits the random access response in the primary cell. Try to receive.

  Specifically, the terminal device 1 detects transmission of a random access response in a section of a specified random access response window size (hereinafter referred to as (RA response window size), also simply referred to as window size) in the primary cell. The physical downlink control channel PDCCH corresponding to the random access response is monitored. The window size is started after, for example, three subframes from the subframe in which the physical random access channel is transmitted. The window size is determined based on the notified random access response window size information.

  In consideration of the above matters, appropriate embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the embodiment of the present invention, when it is determined that a specific description of known functions and configurations related to the embodiment of the present invention obscures the gist of the embodiment of the present invention. Detailed description thereof will be omitted.

<First Embodiment>
A first embodiment of the present invention will be described below.

  FIG. 1 is a block diagram showing an example of a terminal device 1 according to the first embodiment of the present invention. The terminal apparatus 1 includes a reception unit 101, a demodulation unit 102, a decoding unit 103, a measurement processing unit 104, a control unit 105, an uplink buffer control unit 106, an encoding unit 107, a modulation unit 108, a transmission unit 109, and uplink radio resources. The request control unit 110, the random access control unit 111, and the upper layer unit 112 are configured. The upper layer unit 112 is a block that realizes a specific function of an RRC (Radio Resource Control) layer that performs radio resource control as an upper layer of the terminal device 1.

  The uplink buffer control unit 106, the uplink radio resource request control unit 110, and the random access control unit 111 are blocks that realize specific functions of a MAC (Medium Access Control) layer that manages the data link layer. The “unit” in the figure is an element that realizes the function and each procedure of the terminal device 1 that is also expressed by terms such as section, circuit, component device, device, and unit.

  Note that the terminal device 1 is configured to receive a plurality of frequencies (frequency bands, frequency bandwidths) or simultaneous reception of cells by carrier aggregation and / or dual connectivity (reception unit 101, demodulation unit 102). , Decoding section 103) and a plurality of transmission system blocks (coding section 107, modulation section 108, transmission section 109) to support simultaneous transmission of a plurality of frequencies (frequency bands, frequency bandwidths) or cells. There may be. Further, the terminal device 1 may be configured to include a plurality of measurement processing units 104, control units 105, uplink buffer control units 106, uplink radio resource request control units 110, random access control units 111, and higher layer units 112. Good.

  Regarding reception, terminal device control information is input from the upper layer unit 112 to the control unit 105. The terminal device control information is information necessary for wireless communication control of the terminal device 1 configured by the reception control information and the transmission control information. The wireless connection resource setting and the cell-specific notification individually transmitted from the base station device 2 It is set by information or system parameters, and the upper layer unit 112 inputs it to the control unit 105 as necessary. The control unit 105 appropriately inputs reception control information, which is control information related to reception, to the reception unit 101, the demodulation unit 102, and the decoding unit 103.

  The reception control information includes information such as DRX control information, reception timing for each channel, multiplexing method, and radio resource arrangement information in addition to reception frequency band information. Further, the control unit 105 inputs measurement setting information necessary for control related to cell measurement to the measurement processing unit 104. The measurement setting information is information including measurement event information for determining a measurement event as to whether or not the measurement results of the serving cell and the peripheral cell measured by the terminal device 1 satisfy a designated measurement event. Moreover, the measurement setting information is information including neighboring cell information for determining whether or not the measurement result of the neighboring cell measured by the terminal device 1 satisfies the selection criteria regarding cell selection.

  The reception signal is received by the reception unit 101. The receiving unit 101 receives a signal in the frequency band specified by the reception control information. The received signal is input to the demodulation unit 102. Demodulation section 102 demodulates the received signal, inputs a signal to decoding section 103 to correctly decode downlink data and downlink control data, and inputs each decoded data to higher layer section 112. . Each data is also input to the measurement processing unit 104.

  Further, the measurement processing unit 104 measures the reception quality (SIR, SINR, RSRP, RSRQ, RSSI, path loss, etc.) of the downlink reference signal of the detected neighboring cell (component carrier), and generates a necessary measurement result. RSRP is a value indicating the magnitude of the received power of the downlink reference signal, and RSRQ is a value indicating the quality of the downlink reference signal.

  The measurement processing unit 104 uses the measurement result as cell quality information for determining success or failure of the measurement event based on the set measurement event information. Further, the measurement processing unit 104 uses the measurement result as quality information for selection criteria for cell selection or cell reselection based on the set neighboring cell information. In addition, the signal used for the measurement is not limited to the downlink reference signal, and another signal may be measured as long as it is a signal used for measuring cell quality such as CSI-RS.

  Also, regarding transmission, terminal device control information, which is a control parameter for controlling each block, is input from the upper layer unit 112 to the control unit 105, and transmission control information, which is control information regarding transmission, is transmitted to the uplink buffer control unit 106. Are appropriately input to the encoding unit 107, the modulation unit 108, and the transmission unit 109. The transmission control information includes information such as DTX control information, coding information, modulation information, transmission frequency band information, transmission timing for each channel, multiplexing method, and radio resource allocation information as uplink scheduling information of the transmission signal. ing.

  Random access setting information is input from the upper layer unit 112 to the random access control unit 111. The upper layer unit 112 may set a plurality of random access setting information respectively corresponding to a plurality of cells in the random access control unit 111. Further, the upper layer section 112 manages transmission timing adjustment information and a transmission timing timer used for adjustment of uplink transmission timing, and states of uplink transmission timing (transmission timing) for each cell (or for each cell group and each TA group). (Adjustment state or transmission timing non-adjustment state). The transmission timing adjustment information and the transmission timing timer are included in the transmission control information.

  When it is necessary to manage a plurality of uplink transmission timing states, the upper layer section 112 transmits transmission timing adjustment information corresponding to the uplink transmission timing of each of a plurality of cells (or cell groups, TA groups). to manage.

  The generated transmission data (uplink data and uplink control data) is input from the upper layer unit 112 to the uplink buffer control unit 106 at an arbitrary timing. At this time, the uplink buffer control unit 106 calculates the amount of input transmission data (uplink buffer amount). Further, the uplink buffer control unit 106 has a function of determining whether input transmission data is data belonging to the control plane or data belonging to the user plane.

  Resource request setting information is set in the uplink radio resource request control unit 110 by the higher layer unit 112. The resource request setting information is a part of the uplink control channel setting information. The resource request setting information includes at least maximum transmission counter setting information and radio resource request prohibition timer information. The upper layer unit 112 may set a plurality of resource request setting information respectively corresponding to a plurality of cells in the uplink radio resource request control unit 110. Further, when the transmission data is input to the uplink buffer control unit 106, the uplink buffer control unit 106 notifies the uplink radio resource request control unit 110 of the generation of the transmission data, thereby transmitting to the uplink buffer. Signals that data exists.

  The uplink radio resource request control unit 110 determines whether radio resources necessary for transmitting the input transmission data are allocated. The uplink radio resource request control unit 110 generates one of a physical uplink shared channel PUSCH, a radio resource request using a physical uplink control channel (SR-PUCCH), or a physical random access channel based on radio resource allocation. Select and request control processing for transmitting the selected channel to the encoding unit 107 and / or the random access control unit 111.

  That is, when radio resources have already been allocated and transmission data can be transmitted using the physical uplink shared channel PUSCH, the encoding unit 107 allocates radio resources that have been allocated in accordance with an instruction from the uplink radio resource request control unit 110. The transmission data corresponding to is acquired from the uplink buffer control unit 106, encoded, and output to the modulation unit 108. Alternatively, when radio resources are not allocated and when a radio resource request (SR-PUCCH) using a physical uplink control channel is possible, the encoding unit 107 performs SR- in accordance with an instruction from the uplink radio resource request control unit 110. Control data necessary for transmission of PUCCH is encoded and output to modulation section 108.

  Alternatively, when the radio resource is not allocated and the radio resource request (SR-PUCCH) by the physical uplink control channel is impossible, the encoding unit 107 performs the random access procedure for the random access control unit 111. Instruct to start. At this time, the encoding unit 107 generates a preamble sequence transmitted through the physical random access channel based on the random access setting information input from the random access control unit 111. The encoding unit 107 appropriately encodes each data according to the transmission control information and outputs the data to the modulation unit 108.

  Modulation section 108 appropriately performs modulation processing based on the channel structure for transmitting the output from coding section 107. The transmission unit 109 maps the output of the modulation unit 108 to the frequency domain, converts the frequency domain signal into a time domain signal, and performs power amplification on a carrier wave of a predetermined frequency. The transmission unit 109 also adjusts the uplink transmission timing according to the transmission timing adjustment information for each cell (also for each cell group and each TA group) input from the higher layer unit 112. The physical uplink shared channel in which the uplink control data is arranged can include, for example, a layer 3 message (radio resource control message; RRC message) in addition to the user data.

  In FIG. 1, other constituent elements of the terminal device 1 are omitted, but it is obvious that a plurality of blocks having other functions necessary to operate as the terminal device 1 are included as constituent elements.

  FIG. 2 is a block diagram showing an example of the base station apparatus 2 according to the first embodiment of the present invention. The base station apparatus includes a reception unit 201, a demodulation unit 202, a decoding unit 203, a control unit 204, a coding unit 205, a modulation unit 206, a transmission unit 207, an upper layer unit 208, and a network signal transmission / reception unit 209. The “unit” in the figure is an element that realizes the functions and procedures of the base station apparatus 2 that are also expressed by terms such as section, circuit, component device, device, and unit.

  Note that the base station apparatus 2 receives a plurality of frequencies (frequency band, frequency bandwidth) by carrier aggregation and / or dual connectivity in order to support a reception system block (reception unit 201, demodulation unit 202, decoding unit 203). ), And a plurality of transmission system blocks (encoding unit 205, modulation unit 206, transmission unit 207). Moreover, the structure provided with two or more control parts 204, the upper layer part 208, and the network signal transmission / reception part 209 may be sufficient.

  The upper layer unit 208 is a block that implements a specific function of an RRC (Radio Resource Control) layer that performs radio resource control as an upper layer of the base station apparatus 2.

  Upper layer section 208 inputs downlink data and downlink control data to encoding section 205. The encoding unit 205 encodes the input data and inputs it to the modulation unit 206. Modulation section 206 modulates the encoded signal. The signal output from the modulation unit 206 is input to the transmission unit 207. Transmitter 207 maps the input signal to the frequency domain, then converts the frequency domain signal to a time domain signal, transmits the amplified signal on a carrier having a predetermined frequency, and transmits the signal. The physical downlink shared channel in which downlink control data is arranged typically constitutes a layer 3 message (RRC message).

  The receiving unit 201 converts a signal received from the terminal device 1 into a baseband digital signal. When a plurality of cells having different transmission timings are set for the terminal device 1, the receiving unit 201 receives signals at different timings for each cell (also for each cell group and each TA group). The digital signal converted by the reception unit 201 is input to the demodulation unit 202 and demodulated. The signal demodulated by the demodulation unit 202 is then input to the decoding unit 203 and decoded, and the correctly decoded uplink control data and uplink data are output to the upper layer unit 208.

  Base station apparatus control information necessary for control of each block is information necessary for radio communication control of the base station apparatus 2 configured by reception control information and transmission control information, and is a higher-level network apparatus (MME (MME300)). And the gateway device (SGW 400), OAM, etc.) and system parameters, and the upper layer unit 208 inputs the control unit 204 as necessary.

  The control unit 204 transmits base station apparatus control information related to transmission to each block of the encoding unit 205, modulation unit 206, and transmission unit 207 as transmission control information, and base station apparatus control information related to reception to the reception control information. Are appropriately input to each block of the receiving unit 201, the demodulating unit 202, and the decoding unit 203. The RRC of the base station device 2 exists as a part of the higher layer unit 208.

  On the other hand, the network signal transmission / reception unit 209 transmits (transfers) or receives a control message or user data between the base station devices 2 or between the upper network devices (MME300, SGW400) and the base station device 2, or performs maintenance operation. Therefore, a message is transmitted and received between the element management device (Element Manager) that manages the base station device 2 and the base station device 2. In FIG. 2, the other constituent elements of the base station apparatus 2 are omitted, but it is obvious that the constituent elements include a plurality of blocks having other functions necessary to operate as the base station apparatus 2.

  A random access procedure method according to the first embodiment of the present invention will be described. The terminal device 1 is configured to be able to transmit a physical random access channel in a plurality of cells during communication with a plurality of base station devices 2 by dual connectivity. The dual connectivity may be realized by the connection method illustrated in FIG. 5 or FIG. 6, or may be realized by other connection methods.

  FIG. 3 is a diagram illustrating a random access procedure by the terminal device 1 according to the first embodiment of the present invention. The horizontal axis of the figure is the time axis, the lower part of the figure shows the control timing related to the random access procedure in the terminal apparatus 1, and the middle part of the figure shows the control timing related to the random access procedure in the base station apparatus 2-1. The upper part of the figure shows the control timing regarding the random access procedure in the base station apparatus 2-2. Moreover, the arrows in the figure indicate that there is information exchange among the terminal device 1, the base station device 2-1, and the base station device 2-2.

  The terminal device 1 is connected to a cell of a base station device 2-1 that manages a macro cell and a base station device 2-2 that manages a small cell. However, the terminal device 1 cannot adjust the uplink transmission timing for the base station device 2-2, and the uplink cell of the base station device 2-2 is in a transmission timing non-adjusted state.

  Further, it is assumed that the terminal device 1 is connected to a plurality of cells, and a random access procedure is possible for the plurality of cells. That is, the base station apparatus 2 notifies the terminal apparatus 1 of a plurality of random access setting information corresponding to a plurality of cells or cell groups.

  First, the transmission / reception control method of the base station apparatus 2 will be described with reference to FIG. In the present embodiment, as an example of a setting for appropriate random access processing, an example in which an offset value for adjusting the start time of random access response reception in the terminal device 1 is extended is shown, but this embodiment is applied. The random access process is not limited to the method illustrated in FIG.

  Prior to the start of the random access procedure, the base station apparatus 2-1 or the base station apparatus 2-2 starts the window size start time (T12 in FIG. 3) indicating the PDCCH reception section (detection section) corresponding to the random access response. ) Is notified to the terminal device 1 as additional (new) random access setting information. By using this parameter, the offset (T11-T12 interval in FIG. 3) can be set to be longer than the conventional one.

  The base station device 2-2 notifies the terminal device 1 of the start of the random access procedure for the cell of the base station device 2-2 (step S111). As the random access procedure, the Non Contention based Random Access procedure is desirable. That is, the base station apparatus 2-2 assigns an individual preamble to the terminal apparatus 1 in step S111. The base station apparatus 2-2 may notify the start of the random access procedure using the PDCCH, may be notified by the RRC message, or may be notified by the layer 2 message (control element in the MAC header). May be. In addition, the base station apparatus 2-2 may start a Contention based Random Access procedure as a random access procedure by not assigning an individual preamble to the terminal device 1 in step S111.

  In addition, the notification of the start of the random access procedure of step S111 may be notified from the base station apparatus 2-1 to the terminal apparatus 1.

  The terminal device 1 notified of the start of the random access procedure transmits a physical random access channel to the base station device 2-2 using the available radio resources (step S112). When the base station apparatus 2-2 that has received the physical random access channel receives the dedicated preamble allocated to the terminal apparatus 1, the base station apparatus 2-2 calculates transmission timing adjustment information of the terminal apparatus 1 based on the reception timing of the received dedicated preamble. . Then, the base station device 2-2 transmits at least the information of the individual preamble and the transmission timing adjustment information to the base station device 2-1 (step S113).

  Step S113 may be transmitted and received by a message between the base station devices 2. In addition, when the base station apparatus 2-1 receives the information on the individual preamble and the transmission timing adjustment information in a message between the base station apparatuses 2, a reception response message indicating that the information has been successfully received is transmitted to the base station. You may transmit with respect to the apparatus 2-2 (step S114).

  When the base station device 2-1 can transmit the random access response in accordance with the random access response reception timing (between T12 and T13) in the terminal device 1, the base station device 2-1 sends a random access response to the terminal device 1. Is transmitted (step S115). The base station apparatus 2-1 notifies at least the transmission timing adjustment information notified from the base station apparatus 2-2 as a random access response.

  Then, the base station apparatus 2-1 sends a random access response transmission completion message or a random access response transmission failure message to the base station apparatus 2-2 indicating whether or not a random access response has been transmitted to the terminal apparatus 1. Transmit (step S116).

  For example, the random access response transmission completion message may indicate that the random access response has been transmitted in the PDCCH reception period (detection period) corresponding to the random access response.

  Further, for example, the random access response transmission failure message may indicate that the random access response transmission has failed, and may include a reason for failure (Cause). For example, it may be notified that the transmission failed due to a delay of the backbone line, or the transmission failed due to a shortage of radio resources, as the reason for the failure. Further, when transmission is not in time due to the delay of the backbone line, information related to the delay (for example, the timing at which the information is actually received from the base station apparatus 2-2 in step S113 and the random access response transmission is required) (A difference with a proper reception timing) may be notified.

  Further, when the transmission is not in time due to the delay of the backbone line (delay of information reception from the base station apparatus 2-2 in step S113), the base station apparatus 2-1 converts the extended offset information into the delay of the backbone line. The terminal device 1 may be notified by resetting accordingly.

  In addition, when the base station apparatus 2-1 fails to transmit in time due to a delay in the backbone line (delay of information reception from the base station apparatus 2-2 in step S113), the base station apparatus 2-1 sends a random access response from the base station apparatus 2-2. You may make it notify the base station apparatus 2-2 of the setting information set to transmit.

  Also, the base station apparatus 2-1 or the base station apparatus 2-2 performs maintenance operation when transmission is not in time due to a delay of the backbone line (delay of information reception from the base station apparatus 2-2 in step S113). In addition, information regarding delay may be notified to an element management device (Element Manager) that manages the base station device 2.

  By configuring in this way, when the failure of the random access procedure occurs, the base station device 2 determines whether the cause is a problem between the base station devices 2 or between the terminal device 1 and the base station device 2. It becomes possible to isolate the problem, and the base station apparatus 2 can autonomously adjust (change) settings for appropriate random access processing (random access setting information). Alternatively, the operator can change (adjust) the setting to a more appropriate setting for operation. As a result, the terminal device 1 can appropriately perform the random access process according to the situation of the base station device 2. That is, in a communication system in which a delay may occur in the random access processing, the random access processing can be optimized and efficient communication can be performed.

  In addition, the base station device 2-1 may include information on time and order in the random access response transmission completion message and the random access response failure message. For example, the transmission time (time stamp) of the random access response transmission completion message or the random access response failure message may be included, or the message reception time of step S113 may be included. Alternatively, an identifier may be added to the message in step S113, and the identifier may be added to the random access response transmission completion message or the random access response failure message corresponding to the message in step S113. The identifier may be uniquely associated with the number of retransmissions of the random access preamble by the same terminal device, or may be uniquely associated with the transmission time of the message in step S113 by the base station device 2-2. It may be a random value or any other value.

  With this configuration, even when the backbone line delay is large, the base station device 2-2 can receive the random access response transmission completion message or the random access response failure received from the base station device 2-1. It becomes possible to identify which message in step S113 the message corresponds to. In addition, when the time information is included in the message, it is possible to estimate the delay amount of the backbone line.

  In addition, when the base station apparatus 2-2 receives a random access response transmission completion message from the base station apparatus 2-1 when the random access preamble is retransmitted from the terminal apparatus 1, the cause is 1 is recognized as a problem between the base station apparatus 2 and a random access response transmission failure message is received from the base station apparatus 2-1, the cause is recognized as a problem between the base station apparatuses 2. be able to.

<Second Embodiment>
A second embodiment of the present invention will be described below. In the present embodiment, an example in which the terminal device 1 notifies the base station device 2-2 of information regarding the reception timing of the random access preamble in the random access procedure is shown.

  Since the configurations of the terminal device 1 and the base station device 2 according to the second embodiment of the present invention are the same as those of the first embodiment, detailed description will not be repeated.

  FIG. 4 is a diagram illustrating a random access procedure by the terminal device 1 according to the second embodiment of the present invention. The horizontal axis of the figure is the time axis, the lower part of the figure shows the control timing related to the random access procedure in the terminal apparatus 1, and the middle part of the figure shows the control timing related to the random access procedure in the base station apparatus 2-1. The upper part of the figure shows the control timing regarding the random access procedure in the base station apparatus 2-2. Moreover, the arrows in the figure indicate that there is information exchange among the terminal device 1, the base station device 2-1, and the base station device 2-2.

  The terminal device 1 is connected to a cell of a base station device 2-1 that manages a macro cell and a base station device 2-2 that manages a small cell. However, the terminal device 1 cannot adjust the uplink transmission timing for the base station device 2-2, and the uplink cell of the base station device 2-2 is in a transmission timing non-adjusted state.

  Further, it is assumed that the terminal device 1 is connected to a plurality of cells, and a random access procedure is possible for the plurality of cells. That is, the base station apparatus 2 notifies the terminal apparatus 1 of a plurality of random access setting information corresponding to a plurality of cells or cell groups.

  First, the transmission / reception control method of the base station apparatus 2 will be described with reference to FIG. Similarly to the first embodiment, this embodiment shows an example of extending an offset value for adjusting the start time of random access response reception in the terminal device 1 as an example of a setting for appropriate random access processing. However, it is not limited to this.

  Prior to the start of the random access procedure, the base station apparatus 2-1 or the base station apparatus 2-2 starts the window size start time (T12 in FIG. 4) indicating the PDCCH reception section (detection section) corresponding to the random access response. ) Is notified to the terminal device 1 as additional (new) random access setting information. By using this parameter, the offset (T11-T12 interval in FIG. 4) can be set to be longer than the conventional one.

  The base station device 2-2 notifies the terminal device 1 of the start of the random access procedure for the cell of the base station device 2-2 (step S131). As the random access procedure, the Non Contention based Random Access procedure is desirable. That is, the base station apparatus 2-2 assigns an individual preamble to the terminal apparatus 1 in step S131. The base station apparatus 2-2 may notify the start of the random access procedure using the PDCCH, may be notified by the RRC message, or may be notified by the layer 2 message (control element in the MAC header). May be. In addition, the base station apparatus 2-2 may start a Contention based Random Access procedure as a random access procedure by not assigning an individual preamble to the terminal device 1 in step S131.

  In addition, the notification of the start of the random access procedure of step S131 may be notified from the base station apparatus 2-1 to the terminal apparatus 1.

  The terminal device 1 notified of the start of the random access procedure transmits a physical random access channel to the base station device 2-2 using the available radio resources (step S132). When the base station apparatus 2-2 that has received the physical random access channel receives the dedicated preamble allocated to the terminal apparatus 1, the base station apparatus 2-2 calculates transmission timing adjustment information of the terminal apparatus 1 based on the reception timing of the received dedicated preamble. . Then, the base station device 2-2 transmits at least the information of the individual preamble and the transmission timing adjustment information to the base station device 2-1 (step S133).

  Step S133 may be transmitted and received by a message between the base station devices 2. In addition, when the base station apparatus 2-1 receives the information on the individual preamble and the transmission timing adjustment information in a message between the base station apparatuses 2, a reception response message indicating that the information has been successfully received is transmitted to the base station. You may transmit with respect to the apparatus 2-2 (step S134).

  When the base station device 2-1 can transmit the random access response in accordance with the random access response reception timing (between T12 and T13) in the terminal device 1, the base station device 2-1 sends a random access response to the terminal device 1. Is transmitted (step S135). The base station apparatus 2-1 notifies at least the transmission timing adjustment information notified from the base station apparatus 2-2 as a random access response.

  After the random access procedure is normally completed, the base station device 2-2 receives information regarding the reception timing of the random access response from the terminal device 1 (step S136).

  For example, the information regarding the reception timing of the random access response may be time information from when the terminal device 1 transmits a random access preamble until the random access response is received, or may be random access within a random access response window. It may be response reception time information. The reception time information may be subframe information.

  In this way, the base station apparatus 2-2 obtains information on the reception timing of the random access response, thereby notifying the base station apparatus 2-1 to reset the extended offset information according to the delay of the backbone line. Or a random access response can be set to be transmitted from the base station device 2-2.

  Further, the base station apparatus 2-2 may notify the information related to the reception timing of the random access response to an element management apparatus (Element Manager) that manages the base station apparatus 2 for maintenance operation. .

  Next, a transmission / reception control method of the terminal device 1 will be described with reference to FIG.

  When the terminal device 1 is instructed by the base station device 2-2 to start a random access procedure, the terminal device 1 transmits the physical random access channel to the base station at a certain time (T11) when the radio resource for the physical random access channel can be used. It transmits with respect to the apparatus 2-2 (step S132). Also, the terminal device 1 starts the window size for monitoring the reception of the random access response until the time T12 when the extended offset indicated by the extended offset information is applied to the conventional offset (for example, 3 subframes) starting from the time T11. Delay. Then, the terminal device 1 starts monitoring the random access response using the time T12 as the start time of the window size indicating the section for monitoring the reception of the random access response.

  The terminal device 1 tries to receive a random access response from time T12 to time T13 indicating the end time of the window size. In other words, the terminal device 1 monitors the PDCCH corresponding to the random access response for a time corresponding to the length of the window size from the time T12, and receives the PDSCH including the random access response. When the terminal device 1 successfully receives the random access response from time T12 to time T13, the terminal device 1 considers that the random access procedure is successful. On the other hand, if the terminal device 1 does not receive the random access response from time T12 to time T13, it is assumed that reception of the random access response has failed, and the number of preamble retransmissions is incremented, and the base station device 2-2 On the other hand, a physical random access channel using the same dedicated preamble is transmitted.

  After the random access procedure is successful and the uplink resource in the cell of the base station device 2-2 is allocated, the terminal device 1 transmits information on the reception timing of the random access response in the random access procedure to the base station device 2-2. (Step S136).

  Here, the terminal device 1 may be set in advance as to whether or not to transmit information regarding the reception timing of the random access response to the base station device 2-2.

  With this configuration, the base station apparatus 2 can recognize the delay amount of the random access response in the random access procedure, and can perform settings for appropriate random access processing. As a result, the terminal device 1 can appropriately perform the random access process according to the situation of the base station device 2. That is, in a communication system in which a delay may occur in the random access processing, the random access processing can be optimized and efficient communication can be performed.

  In each of the above embodiments, an example of performing random access response reception at an appropriate timing by expanding the offset value of the random access response as a setting for appropriate random access processing has been shown. Absent. For example, as another example of receiving a random access response at an appropriate timing, a method of expanding the window size instead of the random access response offset value is shown below.

  Prior to the start of the random access procedure, the base station apparatus 2-1 adds (new) extended window size information for extending the window size indicating the PDCCH reception section (detection section) corresponding to the random access response. To the terminal device 1 as random access setting information. This parameter value is specified by a value in units of subframes, for example. Then, the base station apparatus 2-1 transmits a random access response to the terminal apparatus 1 in a reception section (extended reception section) to which the window size extended by the parameter value is applied.

  In this way, the terminal device 1 sends the random access response corresponding to the physical random access channel transmitted to the base station device 2-2 to the extended offset information or the extended window size information that is an additional parameter, or those If the transmission of the random access response is not in time due to the delay of the backbone line due to reception in the section indicated by the combination of the extended offset information and the window By adjusting the size information, failure of random access processing can be reduced, and random access processing between the terminal device 1 and the base station device 2 can be performed efficiently.

  In addition, the failure in random access processing is reduced by selecting the base station device 2 that transmits the random access response based on the transmission delay amount of the backbone between the base station device 2-1 and the base station device 2-2. And random access processing between the terminal device 1 and the base station device 2 can be appropriately performed.

Further, in the second embodiment, the terminal device 1 uses the cell configuration instructed (notified) in advance by the RRC message when starting the random access procedure from the base station device 2, thereby performing random access in the second embodiment. You may notify whether the information regarding the reception timing of a response is transmitted to the base station apparatus 2-2.
FIG.

  The embodiment described above is merely an example, and can be realized using various modifications and replacement examples. For example, this uplink transmission scheme can be applied to both communication systems of the FDD (frequency division duplex) scheme and the TDD (time division duplex) scheme. In addition, as the downlink measurement value, path loss or other measurement values (SIR, SINR, RSRP, RSRQ, RSSI, BLER) may be used instead, or a combination of these measurement values may be used. Is also possible. Further, the names of the parameters shown in the embodiments are called for convenience of explanation, and even if the parameter names actually applied and the parameter names of the embodiments of the present invention are different, the present invention It does not affect the gist of the invention claimed in the embodiment.

  The terminal device 1 is not only a portable or movable mobile station device, but also a stationary or non-movable electronic device installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment. It can also be applied to air-conditioning equipment, office equipment, vending machines, other life equipment, measuring equipment, in-vehicle devices, and the like.

  The terminal device is also referred to as a user terminal, a mobile station device, a communication terminal, a mobile device, a terminal, a UE (User Equipment), and an MS (Mobile Station). The base station apparatus is also referred to as a radio base station apparatus, a base station, a radio base station, a fixed station, an NB (Node-B), an eNB (evolved Node-B), a BTS (Base Transceiver Station), and a BS (Base Station). The

  Note that the base station apparatus 2 defined by 3GPP is referred to as a Node B (NodeB), and the base station apparatus 2 in EUTRA and Advanced EUTRA is referred to as an eNodeB (eNodeB). Note that the terminal device 1 in EUTRA and Advanced EUTRA defined by 3GPP is referred to as a UE (User Equipment).

  In addition, for convenience of explanation, the function of each part of the terminal device 1 and the base station device 2 or a part of these functions are realized by using the functional block diagram of the terminal device 1 and the base station device 2 of the embodiment. Although the method, method, means, or algorithm steps of have been described, they can be directly embodied in hardware, software modules executed by a processor, or a combination of the two. If implemented by software, the functions may be maintained or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media includes both communication media and computer recording media including media that facilitate carrying a computer program from one place to another.

  One or more instructions or codes are recorded on a computer-readable recording medium, and one or more instructions or codes recorded on the recording medium are read into a computer system and executed, thereby executing the terminal device 1 or the base. The station device 2 may be controlled. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The operations described in the embodiments of the present invention may be realized by a program. A program that operates in the terminal device 1 and the base station device 2 according to each embodiment of the present invention is a program that controls a CPU or the like (a computer is installed) so as to realize the functions of the above-described embodiments according to each embodiment of the present invention. Program to function). Information handled by these devices is temporarily stored in the RAM at the time of processing, then stored in various ROMs and HDDs, read out by the CPU, and corrected and written as necessary. In addition, by executing the program, not only the functions of the above-described embodiment are realized, but also by processing in cooperation with an operating system or other application programs based on the instructions of the program, The functions of the embodiments may be realized.

  The “computer-readable recording medium” refers to a semiconductor medium (for example, RAM, a non-volatile memory card), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, , A magnetic tape, a flexible disk, etc.) and a storage device such as a disk unit built in a computer system. Furthermore, the “computer-readable recording medium” means that a program is dynamically held for a short time, like a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In this case, it is intended to include those that hold a program for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client in that case.

  Further, the program may be for realizing a part of the above-described functions, and further, may be realized by combining the above-described functions with a program already recorded in a computer system. good.

  In addition, each functional block or various features of the terminal device 1 and the base station device 2 used in each of the above embodiments is a general-purpose processor, a digital signal processor designed to execute the functions described in this specification. (DSP), application specific or general purpose integrated circuit (ASIC), field programmable gate array signal (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or combinations thereof It can be implemented or implemented by something. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The general-purpose processor or each circuit described above may be configured by a digital circuit or an analog circuit.

  The processor may also be implemented as a combination of computing devices. For example, a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors connected to a DSP core, or a combination of other such configurations.

  The embodiments of the present invention have been described in detail based on specific examples. However, it is obvious that the gist and claims of each embodiment of the present invention are not limited to these specific examples. Design changes and the like within the scope not departing from the gist are also included. In other words, the description in the present specification is for illustrative purposes and does not limit the embodiments of the present invention.

  The present invention can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. It is. Moreover, it is an element described in said each embodiment, and the structure which substituted the element which has the same effect is also contained in the technical scope of this invention.

DESCRIPTION OF SYMBOLS 1 ... Terminal device 2, 2-1, 2-2 ... Base station apparatus 101, 201 ... Reception part 102, 202 ... Demodulation part 103, 203 ... Decoding part 104 ... Measurement processing part 105, 204 ... Control part 106 ... Uplink Buffer control unit 107, 205 ... Encoding unit 108, 206 ... Modulation unit 109, 207 ... Transmission unit 110 ... Uplink radio resource request control unit 111 ... Random access control unit 112, 208 ... Upper layer unit 209 ... Network signal transmission / reception unit 300 ... MME
400 ... SGW

Claims (10)

A terminal device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
A response to the physical random access channel transmitted to the first cell is received from the second cell, and information related to the time required to receive the response to the transmitted physical random access channel is transmitted to the base station apparatus. A terminal device for transmitting. A base station device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
Receiving transmission timing adjustment information based on a physical random access channel transmitted from the terminal device to the cell;
Informing the base station apparatus of the cell of information indicating whether or not the response of the physical random access channel has been transmitted to the terminal apparatus in a section for receiving the response of the random access channel set in the terminal apparatus in advance. A base station apparatus characterized by the above.   The base station apparatus according to claim 2, wherein the information indicating whether or not the transmission is possible includes an identifier indicating which transmission timing adjustment information corresponds to the information. A communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
The terminal device transmits a physical random access channel to the first cell, receives a response to the physical random access channel from the second cell, and requires transmission of the physical random access channel to receive the response. Transmitting information on the time to the base station apparatus of the first cell or the base station apparatus of the second cell,
The base station apparatus of the first cell transmits transmission timing adjustment information based on a physical random access channel transmitted from the terminal apparatus to the first cell to the base station apparatus of the second cell,
The base station apparatus of the second cell transmits the transmission timing adjustment information to the terminal apparatus in the second cell. A communication method for a terminal apparatus in a communication system in which a terminal apparatus and a plurality of base station apparatuses are connected using a plurality of cells,
A step of receiving a response to the physical random access channel transmitted to the first cell from the second cell, and information regarding a time required to receive the response to the transmitted physical random access channel to the base station apparatus And a step of transmitting to the communication method. A communication method of a base station device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
Receiving transmission timing adjustment information based on a physical random access channel transmitted from the terminal device to the cell;
And at least a step of notifying the base station apparatus of the cell of information indicating whether or not the response of the physical random access channel has been transmitted in a section for receiving the response of the random access channel set in advance in the terminal apparatus A communication method characterized by the above.   The communication method according to claim 6, wherein the information indicating whether or not the transmission is possible includes an identifier indicating which transmission timing adjustment information corresponds to the information. An integrated circuit mounted on a terminal device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
A function for receiving a response to the physical random access channel transmitted to the first cell from the second cell, and information regarding the time required to receive the response to the transmitted physical random access channel to the base station apparatus An integrated circuit characterized by causing the terminal device to exhibit a series of functions including a function of transmitting to the terminal device. An integrated circuit mounted on a base station device in a communication system in which a terminal device and a plurality of base station devices are connected using a plurality of cells,
A function of receiving transmission timing adjustment information based on a physical random access channel transmitted from the terminal device to the cell;
A function of notifying the base station device of the cell of information indicating whether or not the response of the physical random access channel has been transmitted in a section for receiving the response of the random access channel set in the terminal device in advance. An integrated circuit characterized by causing the base station apparatus to exhibit the above function. 10. The integrated circuit according to claim 9, wherein the information indicating whether or not the transmission is possible includes an identifier indicating which of the transmission timing adjustment information corresponds.