JP2014236366A - 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 efficient random access procedures in a plurality of cells.SOLUTION: A terminal device that connects with a base station device by using a first cell and a second cell performs a random access procedures using a physical random access channel to each of the first cell and the second cell, receives a response to the physical random access channel transmitted to the second cell in the second cell, and transmits information on detection of the response to the first cell.

Description

  Embodiments described herein relate generally to a terminal device, a base station device, a communication system, a communication method, and an integrated circuit technology that realize an efficient random access procedure.

  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.

R2-130644, NTT DOCOMO, INC. , 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 in another example of Non-Patent Document 2, when a terminal apparatus transmits a physical random access channel to uplinks of a plurality of cells, random transmission is performed in the cell of the base station apparatus that has received the physical random access channel. The method for detecting the access response does not need to consider the influence of the backbone delay between the base station apparatuses, but has another problem that the random access procedure of the terminal apparatus has to be greatly changed.

  In particular, when different base station devices are connected by dual connectivity, one base station device cannot know the end of the random access procedure of the other base station device, so the start of data transfer between the base station devices There arises a problem that the timing is unknown and a problem that an appropriate transmission / reception cannot be set for the terminal device. Further, although the end of the random access procedure can be exchanged between the base station apparatuses, another problem that unnecessary signaling occurs between the base station apparatuses occurs.

  In view of the above problems, an object of an embodiment of the present invention is to provide a technology related to a terminal device, a base station device, a communication system, a communication method, and an integrated circuit that realizes an efficient random access procedure. .

  In order to achieve the above object, the following measures were taken. That is, the terminal device in the embodiment of the present invention is a terminal device that communicates with the base station device, and is connected to the base station device using the first cell and the second cell, A random access procedure using a physical random access channel is executed for each of the second cells, and a response of the physical random access channel transmitted to the second cell is received by the second cell. Information on detection is transmitted to the first cell.

  Moreover, the base station apparatus in embodiment of this invention is a base station apparatus which communicates with a terminal device, It connects with a terminal device using a 1st cell and a 2nd cell, A terminal device in a 2nd cell A response corresponding to the physical random access channel transmitted by is transmitted in the second cell, and information on detection of the response is received from the terminal device in the first cell.

  Moreover, the communication system in the embodiment of the present invention is a communication system in which a terminal device and a plurality of base station devices are connected. In the terminal device, a base station device using a first cell and a second cell The response of the physical random access channel transmitted to the second cell is received by the second cell, and information related to detection of the response corresponding to the physical random access channel is transmitted to the first cell. The base station apparatus receives information related to detection of a response transmitted from the terminal apparatus in the first cell.

  Moreover, the communication method of the terminal device in embodiment of this invention WHEREIN: The terminal device connects with a base station apparatus using a 1st cell and a 2nd cell, A 1st cell and a 2nd cell Executing a random access procedure using a physical random access channel for each, receiving a response of the physical random access channel transmitted to the second cell in the second cell, and detecting a response Transmitting the information on the first cell to the first cell.

  In addition, in the communication method of the base station apparatus according to the embodiment of the present invention, the base station apparatus uses the first cell and the second cell to connect to the terminal apparatus, and the second cell transmits by the terminal apparatus. Transmitting a response corresponding to the received physical random access channel in the second cell, and receiving information on detection of the response from the terminal device.

  The integrated circuit of the terminal device in the embodiment of the present invention includes a function of connecting to the base station device using the first cell and the second cell in the terminal device, and the first cell and the second cell. A function of executing a random access procedure using a physical random access channel for each, a function of receiving a response of the physical random access channel transmitted to the second cell by the second cell, and detection of a response The terminal device is caused to exhibit a series of functions including a function of transmitting information on the first cell to the first cell.

  Moreover, the integrated circuit of the base station apparatus in the embodiment of the present invention has a function of connecting to the terminal apparatus using the first cell and the second cell in the base station apparatus, and transmission by the terminal apparatus in the second cell. The base station apparatus has a series of functions including a function of transmitting a response corresponding to the received physical random access channel in the second cell and a function of receiving information on response detection from the terminal apparatus in the first cell. It is characterized by being demonstrated.

  In this specification, each embodiment is disclosed in terms of a technology related to a terminal device, a base station device, a communication system, a communication method, and an integrated circuit that realizes an efficient random access procedure, but is applicable to each embodiment. Such a communication method 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 embodiment of the present invention, it is possible to provide a technology related to a terminal device, a base station device, a communication system, a measurement method, and an integrated circuit that improve communication quality by efficiently performing a random access procedure.

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 a sequence chart figure which shows an example of the random access procedure which concerns on embodiment of this invention. It is a figure for demonstrating the format of the transmission data which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the detail of the format of the transmission data which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the detail of the format of the transmission data which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the detail of the format of another transmission data which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the detail of the format of the transmission data which concerns on 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 written as 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. 9 and 10 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 device 1 and the base station device 2 may apply techniques such as primary cell and secondary cell allocation, activation / deactivation, and the like to cells connected by dual connectivity.

  9 and 10, the base station device 2-1 or the base station device 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.

  9 and 10, 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. 9 can be adopted. In FIG. 9, 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. 10 can be adopted. In FIG. 10, 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. 11 and step S13 in FIG. 12) 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 (RA response window size (hereinafter 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. The upper layer unit 112 manages transmission timing adjustment information and a transmission timing timer used to adjust uplink transmission timing, and performs uplink transmission for each cell (or for each cell group (a cell group is also referred to as a TA group)). The timing state (transmission timing adjustment state or transmission timing non-adjustment state) is managed. 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 base station apparatus sets an identifier for each cell group or TA group, and the upper layer section 112 manages the cell group or TA group using the identifier.

  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 receives one or more of a physical uplink shared channel PUSCH, a radio resource request by 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 apparatuses 2 or between the upper network apparatus (MME300, SGW400) and the base station apparatus 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 each of a plurality of cells used for communication 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. 9 or FIG. 10, or may be realized by other connection methods.

  FIG. 3 is a sequence chart showing a random access procedure according to the first embodiment of the present invention. A base station device 2-1 in the figure is a base station device 2 that manages a macro cell, and a base station device 2-2 is a base station device 2 that manages a small cell. The terminal device 1 uses a random access procedure in order to newly start connection with the cell of the base station device 2-2 from the state of being connected to the cell of the base station device 2-1.

  That is, as an initial state of FIG. 3, the terminal device 1 has not been able to adjust the uplink transmission timing for the base station device 2-2, and the transmission timing is not adjusted for the uplink cell of the base station device 2-2. State. Further, the base station apparatus 2-1 notifies (transmits) the random access setting information in the cell of the base station apparatus 2-2 to the terminal apparatus 1, and the terminal apparatus 1 receives the received base station apparatus 2-2. This is a state in which random access setting information in the cell is held and set.

  The base station apparatus 2-2 notifies the terminal apparatus 1 of information indicating a random access preamble (random access preamble allocation) in order to start a random access procedure for the cell of the base station apparatus 2-2 (step S101). ). That is, the base station apparatus 2-2 assigns an individual preamble to the terminal apparatus 1 as a random access preamble necessary for the Non Contention based Random Access procedure.

  The base station apparatus 2-2 may allocate the random access preamble using the PDCCH, may use the RRC message, or may be multiplexed with the layer 2 message (MAC layer SDU (service data unit)). Control element). Note that the base station device 2-2 may cause the terminal device 1 to start the Contention based Random Access procedure by not assigning an individual preamble to the terminal device 1 in step S101.

  The notification of random access preamble allocation in step S101 may be notified from the base station device 2-1 to the terminal device 1.

  The terminal device 1 notified of the random access preamble assignment transmits a physical random access channel to the base station device 2-2 using the available radio resources (step S102). 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 a reception response (random access response) of the physical random access channel to the terminal device 1 (step S103). The base station apparatus 2-2 notifies the terminal apparatus 1 of at least transmission timing adjustment information as a random access response.

  The base station apparatus 2-2 can transmit the responses of the plurality of terminal apparatuses 1 in one random access response. The random access response is notified by the PDSCH indicated by the PDCCH for RACH response. When the received PDSCH includes information equal to the preamble number of the dedicated preamble transmitted by the terminal device 1, the terminal device 1 determines that the random access response has been normally detected (received) (determination, detection, recognition). The received transmission timing adjustment information is applied to the uplink transmission of the cell of the base station device 2-2.

  Specifically, the terminal device 1 decodes the PDSCH indicated by the PDCCH for RACH response, and the own device transmits the decoded data (MAC PDU (protocol data unit)) to the header part (MAC subheader). When the preamble information is included, the random access response of the message part (MAC payload) corresponding to the position (order) of the MAC subheader including the preamble information is acquired as data addressed to the own apparatus.

  The terminal device 1 that has received the random access response addressed to the own device notifies the base station device 2-1 that the random access procedure has succeeded (completed), and therefore information indicating the completion of the random access procedure (random access) Complete) is transmitted to the base station apparatus 2-1 (step S104).

  The base station device 2-1 that has been notified of the information indicating completion of the random access procedure starts data transfer to the base station device 2-2 (step S105). Alternatively, the base station device 2-1 notifies the base station device 2-1 of transmission / reception control information for the cell of the base station device 2-2. Alternatively, the base station device 2-1 notifies the base station device 2-1 of the completion of the data path change for the cell of the base station device 2-2.

  In addition, the message regarding the activation with respect to the cell of the base station apparatus 2-2 may be notified to the terminal device 1 from the base station apparatus 2-1 before step S101. Moreover, the message regarding the activation with respect to the cell of the base station apparatus 2-2 may be notified to the terminal device 1 from the base station apparatus 2-1 between step S101 and step S102.

  Subsequently, information indicating completion of the random access procedure (random access completion) will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a diagram for explaining a format (data structure) of transmission data including information indicating completion of the random access procedure according to the first embodiment of the present invention. In FIG. 4, transmission data is arranged in order from the left end. The terminal device 1 generates information indicating completion of the random access procedure in the MAC layer, and arranges the information according to the data structure shown in FIG.

  The MAC PDU in FIG. 4 is classified into two areas: a MAC header and a MAC payload. Here, the MAC header indicates information for identifying each part (data structure) included in the MAC payload, which is arranged in the head area of the MAC PDU. The MAC header is composed of one or a plurality of MAC PDU subheaders (also referred to as MAC subheaders). Each MAC PDU subheader corresponds to one MAC SDU (described later), one MAC control element, or padding. The MAC payload is configured by any one of a MAC control element, MAC SDU and Padding, or a combination thereof.

  Further, the MAC control element in FIG. 4 is used to report to the base station device 2 a control command for controlling each function of the terminal device 1 in the MAC layer or a measured value measured in the terminal device 1. It is done. The MAC control element is arranged before the MAC SDU. For example, a BSR (Buffer Status Report) indicating the uplink buffer amount is notified from the terminal device 1 as the MAC control element. The value reported as BSR is information obtained by quantizing the state of the untransmitted uplink data buffer of the terminal device 1 and is transmitted from the terminal device 1 to the base station device 2. The format used for notifying the BSR is determined by the LCH ID (LCID).

  Further, the MAC SDU in FIG. 4 means a service data unit in the MAC layer, and is a bit string composed of aligned bytes (multiple of 8 bits).

  Further, “Padding” in FIG. 4 is a bit string that is added to the end of the MAC PDU when necessary, and is used to adjust the length of the MAC PDU.

  FIG. 5A is a diagram showing an identifier number related to completion of the random access procedure as information indicating completion of the random access procedure. The terminal device 1 includes a bit string of 1 octet (1 oct = 8 bits) shown in FIG. 5A in the MAC subheader. The “R” field in the figure indicates a reserve bit and is set to 0 (zero). The “E” field in the figure is a 1-bit flag indicating whether or not the MAC subheader field is the end. When 1 is set, it indicates that another MAC subheader exists next. When 0 (zero) is set, it indicates the end of the MAC subheader, and indicates that any of the MAC control element, MAC SDU, or padding is present.

  The “LCH ID (LCID)” field in the figure indicates 5-bit index information, and each index information value (index value) corresponds to the contents of the MAC payload. That is, the number of MAC subheaders included in the MAC header is equal to the total number of MAC control elements, MAC SDUs, and padding included in the MAC payload. In the present embodiment, in particular, an index value corresponding to a MAC control element indicating completion of a random access procedure is set in the LCH ID field. For example, when including the MAC control element indicating the completion of the random access procedure, the terminal device 1 sets a binary bit string (for example, “11000”) in the LCH ID field of the corresponding MAC subheader.

  FIG. 5B shows an example in which a TA group identifier for which the random access procedure is completed is included as a MAC control element indicating completion of the random access procedure. The “TAG ID” field in the figure is a bit string indicating a TA group identifier (cell group identifier), and is set to “01”, for example. The “R” field in the figure indicates a reserve bit and is set to 0 (zero). In the figure, 2 bits are assigned to the “TAG ID” field, but a number of bits other than 2 bits may be assigned.

  FIG. 5C shows an example in which an identifier (Random Access Preamble ID: RAPID) of a random access preamble used in the random access procedure is included as a MAC control element indicating completion of the random access procedure. The “RAPID” field in the figure is a bit string indicating a random access preamble number (individual preamble) notified from the base station apparatus 2 and is set to “000001”, for example. The “R” field in the figure indicates a reserve bit and is set to 0 (zero). In the figure, 6 bits are assigned to the “RAPID” field, but a number of bits other than 6 bits may be assigned.

  When the terminal device 1 successfully completes the random access procedure for the base station device 2-2 and there is a PUSCH transmission opportunity for the base station device 2-1, the MAC subheader of FIG. Is set in the MAC header, and the MAC information element of FIG. 5B or 5C is set in the MAC payload, and a MAC PDU including at least these is generated. The generated MAC PDU is also referred to as RACH message 3 (Msg3). Then, the terminal device 1 encodes this MAC PDU (RACH message 3) and transmits it to the base station device 2-1.

  With this configuration, the terminal device 1 and the base station device 2 can perform a random access procedure corresponding to a plurality of cells or cell groups. That is, when receiving a random access response from one base station apparatus 2, the terminal apparatus 1 can notify the other base station apparatus 2 of the completion of the random access procedure.

  Since the terminal device 1 according to the present embodiment can notify the success of the random access procedure without causing an exchange between the base station devices 2, it is possible to implement an efficient random access procedure. That is, the terminal device 1 implements an efficient random access procedure by reducing the time until it is determined that the random access procedure is completed in a network in which a delay occurs in a line between a plurality of cells. It becomes possible. Moreover, since the base station apparatus 2 of this embodiment is notified of the success of the random access procedure from the terminal apparatus 1, it is possible to reduce signaling between the base station apparatuses 2.

  According to the first embodiment, since the terminal device 1 can perform a random access procedure including an appropriate random access termination procedure, the random access procedure is made efficient. Further, since the base station apparatus 2 can cause the terminal apparatus 1 to execute an efficient random access procedure including an appropriate random access termination procedure, the base station apparatus 2 shortens the random access procedure of the terminal apparatus 1, and Signaling between the base station devices 2 can be reduced.

  The terminal device 1 determines whether or not to notify the base station device 2-1 of information indicating completion of random access from the base station device 2-1 or the base station device 2-2, or information indicating completion of random access. You may be made to be notified to which base station apparatus 2 it transmits.

  Thereby, based on whether there is a line delay between the base station apparatuses 2 (between cells), information indicating the completion of random access is transmitted to the specific base station only when the terminal apparatus 1 needs to be notified of completion of random access. Since notification to the device 2 is possible, an efficient random access procedure can be realized.

<Second Embodiment>
A second embodiment of the present invention will be described below.

  Next, a second embodiment of the present invention will be described. In the first embodiment, an example of newly defining a MAC control element indicating completion of a random access procedure is shown. However, in this embodiment, completion of a random access procedure is indicated using an existing MAC control element or PUCCH. A method will be described. Since the configuration of the terminal device 1 and the base station device 2 and the method of the random access procedure of the second embodiment may be the same as those of the first embodiment, description thereof will be omitted.

  Information (random access completion) indicating completion of the random access procedure in the second embodiment of the present invention will be described.

  For example, the terminal apparatus 1 may transmit an E-PHR MAC control element (Extended Power Headroom MAC Control Element) as the MAC control element to the base station apparatus 2-1 as information indicating completion of the random access procedure. . The E-PHR MAC control element obtains information (power headroom information) on the difference between the maximum transmission power of the terminal device 1 and the estimated transmission power of the current terminal device 1 in the primary cell, or the primary cell and the secondary cell. It is a MAC control element used for notifying to. FIG. 6 shows a detailed example of the E-PHR MAC control element.

  The “Ci (i = 1 to 7)” field in the figure is a bit string indicating which secondary cell power headroom information is included in the MAC control element among a plurality of secondary cells. The “P” field is 1-bit information indicating whether power back-off is applied. The “V” field is 1-bit information indicating whether the power headroom information is based on actual transmission power. The “PH” field is 6-bit information indicating power headroom information in the terminal device 1. The “Pcmax, c” field indicates the power level used for calculating the corresponding power headroom information.

  The terminal device 1 can indicate the completion of the random access of the cell by notifying the base station device 2-1 of the E-PHR MAC control element including the information of the cell (secondary cell) that has completed the random access procedure. . Specifically, the terminal device 1 sets the bit of the “Ci” field corresponding to the secondary cell that has started the random access procedure to “1”, and further corresponding “P”, “V”, “PH”. , “Pcmax, c” is set to an appropriate value in each field and transmitted to the base station apparatus 2-1.

  Alternatively, the terminal device 1 uses the 1 bit or 2 bits of the reserved bits of the power headroom information corresponding to the cell (secondary cell) that has completed the random access procedure included in the E-PHR MAC control element. You may make it show completion to the base station apparatus 2-1. That is, in FIG. 6, the terminal device 1 may set the “R” field in the octet corresponding to “R / R / Pcmax, c” corresponding to the cell that has completed the random access procedure to 1.

  By receiving the E-PHR MAC control element from the terminal device 1, the base station device 2-1 can generate a random response to the base station device 2-2 of the terminal device 1 without causing an exchange between the base station devices 2. Recognize that the access procedure was successful.

  For example, the terminal device 1 may transmit the BSR related to the base station device 2-2 as information indicating completion of the random access procedure to the base station device 2-1 as the MAC control element. FIG. 7 shows a detailed example of the BSR MAC control element.

  FIG. 7A shows Short BSR, and FIG. 7B shows Long BSR. The “LCG ID” field is a logical channel group identifier corresponding to the uplink buffer amount to be reported. The “Buffer Size (Buffer Size #n: n = 0 to 3)” field is 6-bit information indicating the uplink buffer amount.

  The base station device 2-1 receives the BSR MAC control element related to the base station device 2-2 from the terminal device 1, so that the base station device 2 of the terminal device 1 does not generate an exchange between the base station devices 2. -2 can be recognized as a successful random access procedure. In addition, the terminal device 1 may transmit the BSR MAC control element regarding the base station device 2-1.

  For example, the base station apparatus 2-1 may determine that the random access procedure has been completed by receiving the physical uplink control channel PUCCH from the terminal apparatus 1. For example, the base station apparatus 2-1 may determine that the random access procedure has been completed by receiving a measurement report message from the terminal apparatus 1.

  Thus, when the random access procedure for the base station device 2-2 is completed successfully and there is a transmission opportunity for the base station device 2-1, the terminal device 1 implicitly completes the random access procedure. Generating a MAC PDU, a PUCCH, or a measurement report message including a MAC information element indicated or explicitly, and transmitting it to the base station apparatus 2-1, thereby generating an exchange between the base station apparatuses 2 It can be recognized that the random access procedure for the base station device 2-2 of the terminal device 1 is successful.

  With this configuration, the terminal device 1 and the base station device 2 can perform a random access procedure corresponding to a plurality of cells or cell groups. That is, when receiving a random access response from one base station apparatus 2, the terminal apparatus 1 can notify the other base station apparatus 2 of the completion of the random access procedure.

  Since the terminal device 1 according to the present embodiment can notify the success of the random access procedure without causing an exchange between the base station devices 2, it is possible to implement an efficient random access procedure. That is, the terminal device 1 implements an efficient random access procedure by reducing the time until it is determined that the random access procedure is completed in a network in which a delay occurs in a line between a plurality of cells. It becomes possible. Moreover, since the base station apparatus 2 of this embodiment is notified of the success of the random access procedure from the terminal apparatus 1, it is possible to reduce signaling between the base station apparatuses 2.

  According to the second embodiment, since the terminal device 1 can perform a random access procedure including an appropriate random access termination procedure, the random access procedure is made efficient. Further, since the base station apparatus 2 can cause the terminal apparatus 1 to execute an efficient random access procedure including an appropriate random access termination procedure, the base station apparatus 2 shortens the random access procedure of the terminal apparatus 1, and Signaling between the base station devices 2 can be reduced.

  Whether or not the terminal device 1 notifies the base station device 2-1 of information indicating completion of random access from the base station device 2-1 or the base station device 2-2 by using an existing MAC control element or PUCCH. Alternatively, the base station apparatus 2 may be notified of information indicating completion of random access.

  Thereby, based on whether there is a line delay between the base station apparatuses 2 (between cells), information indicating the completion of random access is transmitted to the specific base station only when the terminal apparatus 1 needs to be notified of completion of random access. Since notification to the device 2 is possible, an efficient random access procedure can be realized.

<Third Embodiment>
A third embodiment of the present invention will be described below.

  In the embodiment described above, only the success of the random access procedure is notified to the base station apparatus 2-1. Therefore, in the third embodiment, a method of transmitting information to the base station apparatus 2-1 by adding information indicating success / failure of the random access procedure for the base station apparatus 2-2 will be described.

  An example in which information indicating success or failure of the random access procedure is added to the MAC control element will be described with reference to FIG.

  FIGS. 8A and 8B show examples in which additional bit information indicating success or failure of the random access procedure is included in FIGS. 5A and 5B, respectively. The meanings of the “TAG ID” field, the “R” field, and the “TAG ID” field in the figure are the same as those in FIG. 5A or 5B.

  The “S” field in the figure indicates a success / failure bit of the random access procedure. When 0 (zero) is set, the random access procedure is successful. When 1 is set, the random access procedure is failed. The meaning of the bits may be reversed, that is, when 0 (zero) is set, the random access procedure may fail, and when 1 is set, the random access procedure may be successful.

  Further, the “S” field may be extended to 2 bits (or more) to indicate the meaning of being executed in the cell of the base station apparatus 2 having the random access procedure. By notifying the information that the random access procedure is being executed, the base station device 2 can avoid instructing the random access procedure in the terminal device 1 in parallel.

  Information indicating the success or failure of the random access procedure can also be notified using a reserve bit of an existing MAC control element. For example, the success or failure of the random access procedure may be notified using 1 bit of the reserved bit (“R” field) of the cell in which the random access procedure of the E-PHR MAC control element described in FIG. 6 is performed. Similarly, information indicating the success or failure of the random access procedure can be included in the BSR MAC control element described with reference to FIG.

  Further, the terminal device 1 notifies the failure of the random access procedure by setting a unique binary bit string (for example, “10111”) for indicating that the random access procedure has failed in the “LCH ID” field. It may be configured as follows. Further, the terminal device 1 is configured to notify the failure of the random access procedure by setting a unique binary bit string (for example, “000000”) indicating that the random access procedure has failed in the “RAPID” field. May be.

  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, 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 (11)

A terminal device that communicates with a base station device,
Connecting to the base station apparatus using the first cell and the second cell, and performing a random access procedure using a physical random access channel for each of the first cell and the second cell;
A response of the physical random access channel transmitted to the second cell is received by the second cell;
A terminal device that transmits information on detection of the response to the first cell.   The terminal apparatus according to claim 1, wherein information indicating that the response is detected is multiplexed with transmission data for the first cell and transmitted to the first cell.   The information indicating that the random access procedure failed because the response could not be detected is multiplexed with the transmission data for the first cell and transmitted to the first cell. The terminal device described.   The terminal apparatus according to claim 1, wherein the information includes at least a transmission timing group identifier of the second cell. A base station device that communicates with a terminal device,
Connect to the terminal device using the first cell and the second cell,
A response corresponding to the physical random access channel transmitted by the terminal device in the second cell is transmitted in the second cell;
The base station apparatus which receives the information regarding the detection of the response from the terminal apparatus in the first cell.   The base station apparatus according to claim 5, wherein success or failure of a random access procedure of the terminal apparatus in the second cell is determined based on the response. A communication system in which a terminal device and a plurality of base station devices are connected,
The terminal device
The first cell and the second cell are used to connect to the base station apparatus, the physical random access channel response transmitted to the second cell is received by the second cell, and the physical random Sending information about detection of the response corresponding to the access channel to the first cell;
The base station device
A communication system, wherein information related to detection of the response transmitted from the terminal device is received in the first cell. A communication method of a terminal device that communicates with a base station device,
A step of connecting to the base station apparatus using the first cell and the second cell, and a random access procedure using a physical random access channel for each of the first cell and the second cell are executed. And steps to
Receiving the response of the physical random access channel transmitted to the second cell at the second cell;
Transmitting at least information on detection of the response to the first cell. A communication method of a base station device that communicates with a terminal device,
Connecting to the terminal device using a first cell and a second cell;
Transmitting a response corresponding to the physical random access channel transmitted by the terminal device in the second cell in the second cell;
Receiving at least information on detection of the response from the terminal device in the first cell. An integrated circuit of a terminal device that communicates with a base station device,
A function of connecting to the base station apparatus using the first cell and the second cell, and a random access procedure using a physical random access channel for each of the first cell and the second cell is executed. Function and
A function of receiving, in the second cell, a response of the physical random access channel transmitted to the second cell;
An integrated circuit characterized by causing the terminal device to exhibit a series of functions including a function of transmitting information relating to detection of the response to the first cell. An integrated circuit of a base station device that communicates with a terminal device,
A function of connecting to a terminal device using the first cell and the second cell;
A function of transmitting, in the second cell, a response corresponding to the physical random access channel transmitted by the terminal device in the second cell;
An integrated circuit characterized by causing the base station apparatus to exhibit a series of functions including a function of receiving information on detection of the response from the terminal apparatus in the first cell.