RU2425458C2 - Method of transmitting downlink control signal - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: method involves multiplexing the downlink control signal such that if there exists downlink data transmission to given user equipment (UE), localised allocation to a transmission of the downlink control signal including scheduling information on the uplink data transmission of the UE is applied, and distributed allocation to another transmission of the downlink control signal is also applied and the multiplexed downlink control signal is transmitted.

EFFECT: efficient use of localised and distributed allocations when transmitting an downlink control signal.

13 cl, 12 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a multi-carrier mobile communication system and, more particularly, to a downlink control signal structure, and also to a method for transmitting it. Although the present invention is suitable for widespread use, it is particularly suitable for transmitting a control signal necessary for more efficient data transmission in the downstream / upstream directions.

BACKGROUND OF THE INVENTION

In general, in a multi-carrier mobile communication system, a base station transmits downstream data packets to user equipment units (UEs) (user equipments - note. Translation.) Belonging to each of at least one or more cells.

There can be many pieces of user equipment within a cell. Each user equipment cannot know when the data packet will be received or what type of data packet will be received. Therefore, when the base station transmits a downstream data packet to a specific user equipment (hereinafter abbreviated as UE), such necessary information as an identifier (ID) of a user equipment (UE) for receiving a corresponding data packet, a time-frequency domain for transmitting a data packet, a data transport format including coding rate, modulation scheme, etc., information related to hybrid automatic request for retransmission of data (HARQ), etc., should be transmitted in the downstream direction enii for each transmission of the downlink data packet.

Conversely, in order to allow the user equipment (UE) to transmit such necessary information as the data packet in the upstream direction, the base station must transmit the identifier of the user equipment (UE) that is allowed to transmit the data packet, the time-frequency domain of the upstream direction for the user equipment ( UE) for the purpose of transmitting a data packet, a data transport format, including a coding rate, a modulation scheme, and the like, information related to a hybrid automatic request for data retransmission (HARQ), etc. in the downlink for each transmission of the uplink data packet.

In the case of transmitting an uplink data packet, the base station must transmit to the corresponding user equipment (UE) in the downstream channel information on acknowledgment / non-acknowledgment (ACK / NAK - acknowledgement / non-acknowledgement) for each data packet transmitted by this user equipment (UE). Moreover, the base station must transmit the transmission power control information to each user equipment (UE) in the downstream direction to maintain the transmit / receive power of the upstream direction of the corresponding user equipment (UE) at a proper level.

For convenience of explanation in the following description, all information transmitted at physical layers for transmitting and receiving data between a base station and a user equipment (UE) is referred to as “downstream control information”. And the signal carrying the specified information is called the “downstream control signal”.

In more detail, downstream control information can be categorized as follows:

1. Upstream / Downstream Planning Information:

(1) Category A information: user equipment (UE) identifier (ID) for transmitting / receiving data packets, time-frequency domain allocation information for transferring data packets, etc.

(2) Category B information: data transport format, for example, coding rate, modulation scheme, etc., information related to hybrid automatic data retransmission request (HARQ), etc.

2. Information not related to downstream data:

(1) Confirmation / Non-Confirmation Information (ACK / NAK), Power Management Information, etc.

For the system to operate efficiently, it is necessary to efficiently multiplex the downstream control signal to transfer the aforementioned control information with data packets and other downstream signals in downstream time-frequency resources.

To this end, the following describes the general method of transmitting a downward signal.

First of all, the transmission system of the downstream data packet can be mainly divided into categories with localized allocation and distributed allocation.

With localized allocation, data for one unit of user equipment (UE) is transmitted in a relatively limited frequency band through successive subcarriers. The base station scheduler selects a frequency band having a good frequency response for the radio channel for each user equipment unit (UE) based on the frequency response reported by the user equipment units (UEs) within the cell about the downlink radio channel, and then transmits the data. Therefore, the transmission efficiency of the cell can be improved. For reference, in localized allocation, the base station can, if necessary, transmit data to one unit of user equipment (UE) via subcarriers within at least two frequency-discrete bands.

With distributed allocation, data for one unit of user equipment (UE) is transmitted over a relatively wide frequency band within the system bandwidth by targeted allocation. Distributed allocation is suitable for the case where it is difficult for the base station planner to estimate the frequency response of the downlink radio channel for a user equipment (UE) or apply the frequency response to schedule a downlink data packet. Since one data packet is transmitted in a wide frequency band, gain due to frequency diversity is obtained. Therefore, the reception quality of the data packet can be improved.

In the following description, a downlink transmission system supports both localized allocation and distributed allocation for transmitting a downlink data packet. In addition, it is contemplated that data packets transmitted differently within the same transmission time interval may be jointly multiplexed.

For clarity of the following description, the basic unit of the time-frequency domain for transmitting a data packet is referred to as a “resource block” (hereinafter abbreviated RB - resource block). It is also assumed that a single resource block includes a plurality of subcarrier regions from end to end of a plurality of OFDM symbols (OFDM - Orthogonal Frequency Division Multiplexing - orthogonal frequency division multiplexing, note. Translation.).

Figure 1 presents a diagram of the structure for transmitting a downward signal by localized allocation.

1, if within the system bandwidth there are 288 subcarriers used for downlink transmission, and if one resource block (RB) includes 12 subcarriers over 6 OFDM symbols, then for every 6 OFDM symbols in the downstream direction, 24 resource blocks (RBs). In this case, provided that the resource block (RB) for localized allocation is usually called a localized virtual resource block (LVRB), such a localized virtual resource block (LVRB), as shown in FIG. 1, is formed with 12 consecutive subcarriers. From the example of FIG. 1, in which localized virtual resource blocks (LVRBs) are allocated to user equipment UE1, it follows that localized allocation can be performed by transmitting data through localized virtual resource blocks (LVRBs), one after another, for one user unit equipment (UE).

Moreover, from an example in which localized virtual resource blocks (LVRBs) are allocated to user equipment UE2, it follows that data is transmitted to one unit of user equipment through localized virtual resource blocks (LVRBs) spaced one from the other in the frequency domain. Therefore, the result is a distributed allocation effect for gaining due to frequency diversity.

On figa and on figv presents a diagram of the structure for transmitting downward signals by distributed allocation.

In contrast to FIG. 1, provided that the localized virtual resource block (LVRB) for distributed allocation is called a distributed virtual resource block (DVRB), this distributed virtual resource block (DVRB), as shown in FIG. 2A or FIG. 2B may be formed with subcarriers separated from one another by a frequency domain or a time-frequency domain. In this case, according to FIGS. 2A and 2B, even if the data totaling one resource block (RB) or a small number of resource blocks (RBs) is transmitted to one user equipment unit (UE), then they are transmitted with distribution over a wide frequency range through discrete subcarriers using distributed virtual resource blocks (DVRBs). In this way, distributed allocation can be made.

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

Despite the fact that the transmission scheme of the data packet in the transmission of the downward signal, as noted in the above description, explicitly includes localized allocation, distributed allocation and their combination, the transmission scheme of the above downward control signal with the downward data packet by localized and / or distributed allocation is not has been clearly specified or proposed. Therefore, it became necessary to discuss an effective method for transmitting a control signal containing scheduling information for transmitting downlink data in downlink control signals, a control signal containing scheduling information for transmitting downlink data, and the like. taking into account their characteristics.

TECHNICAL SOLUTION

Accordingly, the present invention is directed to a downlink control signal structure and a transmission method thereof that substantially eliminate one or more problems due to limitations and disadvantages of the prior art.

An object of the present invention is to provide a downlink control signal structure and a transmission method by which localized allocation and distributed allocation are effectively used in transmitting a downlink control signal.

Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice. The objectives and other advantages of the invention will be realized and achieved using the structure set forth in detail in the presented description and claims, as well as in the accompanying drawings.

To achieve these and other advantages, and in accordance with the purpose of the present invention, as presented in the examples of its implementation and widely described, a method for transmitting a downlink control signal including scheduling information for uplink data transmission and transmitted by a base station according to the present invention includes multiplexing operations downstream control signal, if downstream data is transmitted to a specified user equipment (UE), by applying the locale a dedicated allotment for transmitting the downlink control signal, including scheduling information for transmitting the uplink data of the user equipment (UE), and applying the distributed allotment to another transmission of the downlink control signal and transmitting the multiplexed downlink control signal.

Preferably, the downlink control signal is multiplexed and transmitted by using distributed allocation for at least one OFDM symbol from the available first OFDM symbol and using localized allocation for other OFDM symbols following one at least OFDM symbol.

More preferably, the downstream control signal allocated by the distributed allocation is isolated as distributed by a group unit from a predetermined number of consecutive subcarriers, adopted by the resource block (RB) used for transmitting uplink data, or a multiple thereof.

Preferably, the downlink control signal transmitted using localized allocation is carried by a partial area of a resource block (RB) carrying downstream data to a user equipment (UE).

More preferably, the number of at least one OFDM symbol used for distributed allocation and the number of OFDM symbols used for localized allocation are directed to all user equipment units (UEs) within the cell via a common downlink channel.

More preferably, if the downlink control signal transmitted with distributed allocation includes information on scheduling transmission of downlink data to a predetermined user equipment (UE), this downlink control signal includes an indicator indicating whether information on scheduling of transmission of downlink data for user equipment (UE) is carried. within a resource area carrying downstream data to a user equipment (UE).

Preferably, the uplink data scheduling information included in the downlink control signal indicates a group of resource blocks used for the uplink scheduled transmission.

Preferably, a subcarrier that fails to carry a downlink control signal and refers to subcarriers within at least one OFDM symbol set to enable transmission of a downlink control signal carries downstream data.

More preferably, the base station notifies the amount of time-frequency resource for transmitting the downlink control signal for at least one OFDM symbol set to enable transmission of the downlink control signal.

Moreover, the base station and all units of user equipment (UEs) located within the same cell and served by the indicated base station, know the information about the transmission scheme of the downward control signal, previously adopted in accordance with the volume of the time-frequency resource carrying the downward control signal.

In this case, the previously adopted scheme for transmitting a downward control signal in accordance with the amount of time-frequency resource carrying a downward control signal is used to transmit a downward control signal in the order of characters starting from the first available OFDM symbol.

More preferably, the base station notifies about the amount of time-frequency resource carrying a downward control signal for at least one OFDM symbol set to enable the transmission of a downward control signal, as well as about the amount of time-frequency resource not used as for transmission downstream control signal, and to transmit downstream data.

More preferably, the base station notifies about the amount of time-frequency resource carrying downstream data for at least one OFDM symbol set to enable the transmission of the downlink control signal.

Preferably, the number of upstream data packets that can be transmitted during the transmit time interval (TTI) and the number of downstream data packets that can be transmitted during the transmission time interval (TTI) are set to less than the maximum number of upstream data packets that can be transmitted during the transmission time interval (TTI), as well as the maximum number of downstream data packets that can be transmitted during the transmission time interval (TTI), respectively.

Preferably, the number of units of uplink transmission planning information that can be transmitted during a transmission time interval (TTI), the number of units of downlink data transmission planning information, and the total amount obtained by adding the previous amounts are set to less than the maximum number of information units scheduling that can be transmitted within a transmission time interval (TTI).

Preferably, information indicating which allocation, distributed or localized, is used by each user equipment (UE) to receive a downstream control signal is received earlier for a period of time longer than the transmission time interval (TTI), while the base station informs the information in advance intended for each user equipment (UE) corresponding to the user equipment (UE) by signaling on the radio resource control channel (RRC signals nation).

Preferably, the corresponding user equipment (UE) searches for a predetermined resource area having the quality of the downlink radio channel, which is reported to be good, through the quality information of the downlink control signal communicated to the base station by the corresponding user equipment (UE) for the downlink control signal transmitted by localized isolation.

Preferably, the base station reports in bit format information on a resource area carrying a downlink control signal using localized allocation to all units of user equipment (UEs) within the cell.

Preferably, the downstream control signal transmission format is preassigned to each user equipment (UE) for a period of time longer than 1 transmission time interval (1 TTI), and the base station previously informs the downstream control signal transmission format to each user equipment (UE) by signaling on radio resource control channel (RRC signaling).

It should be understood that both the previous general description and the following detailed description are exemplary and explanatory and are intended to further clarify the claimed invention.

USEFUL RESULTS

Accordingly, the present invention provides the following results or advantages.

First of all, the method for transmitting a downlink control signal in accordance with one embodiment of the present invention takes into account the advantages and disadvantages of localized allocation and distributed allocation, thereby contributing to both transmission efficiency at localized allocation and gaining due to frequency diversity in distributed allocation.

Secondly, in the structure of the downward control signal transmitted by localized allocation and distributed allocation, the transmission signal by the general distributed resource allocation is provided at the front end of one transmission time interval (TTI), and the transmission signal by localized allocation is provided at the rear end of the corresponding time interval Transmission (TTI). Therefore, the present invention can flexibly cope with the magnitude of the control signal.

Thirdly, an indicator for control information, taken into account during localized allocation, or something like that is included in the part by distributed allocation of resources, thereby the reception efficiency can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, included in the description for further understanding of the invention and constituting an integral part of this description, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

figure 1 shows a diagram of a structure for transmitting a downward signal by localized allocation;

on figa and figv shows a diagram of the structure for transmitting a downward signal by distributed allocation;

FIGS. 3A and 3B are structural diagrams for transmitting a downlink control signal for a first available OFDM symbol by distributed allocation in accordance with one embodiment of the present invention;

4 is a diagram of a structure for transmitting a downlink control signal by localized allocation after an OFDM symbol by distributed allocation in accordance with one embodiment of the present invention;

5 is a diagram of a structure for transmitting downlink data to a resource unit to which a control signal is not transmitted within an OFDM symbol for transmitting a downlink control signal in accordance with one embodiment of the present invention;

FIG. 6 shows a diagram of a general structure for transmitting a downlink channel control signal in connection with FIG. 4 and FIG. 5 according to one embodiment of the present invention;

Fig. 7 shows a diagram of a change in the volume of a time-frequency resource necessary for transmitting a scheduling signal in various formats for transmitting scheduling information;

FIGS. 8A and 8B schematically show examples of how user equipment units (UEs) having different scheduling information transmission formats assigned to them search for scheduling signals in accordance with one embodiment of the present invention; and

Fig. 9 schematically shows an example of how user equipment units (UEs) having assigned transmission formats search for scheduling signals if different scheduling information transmission formats differ in priority.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be described in detail, examples of which are illustrated in the accompanying drawings. In the following description, the scheduling signal is mainly used as a downlink control signal. However, it is obvious that the present invention can also be applied to other downstream control signals.

In the following description, details are included to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these details. For a better understanding of the invention, well-known structures and devices are omitted or presented in the form of block diagrams for the main functions of the respective structures and devices. Where possible, the same item numbers will be used in the drawings to refer to the same or similar parts.

A method of multiplexing a downlink control signal using appropriately both localized allocation and distributed allocation according to one embodiment of the present invention is explained as follows.

First of all, by tacit agreement with the aforementioned transmission of the downlink data packet, the downlink scheduling signal, which is a control signal carrying scheduling information on downstream data, can be transmitted by localized allocation or distributed allocation.

For example, when transmitting a data packet to a predetermined user equipment (UE), in the event that a downlink data packet is transmitted by localizing in a particular frequency band adopted as having a good downlink radio channel characteristics for the corresponding user equipment (UE), it is possible to improve reception efficiency the scheduling signal so that the scheduling signal for transmitting the downlink data packet is transmitted in the same frequency band (i.e., in that part of the band in which Reda downlink data packet).

Conversely, as in the case where a data packet is transmitted by distributed allocation to a user equipment (UE), the characteristics of the downlink of which is difficult to evaluate or which is difficult to reflect in the transmission of the downlink data packet, the scheduling signal is transmitted by distribution over a wide band. Therefore, when a scheduling signal is received, gain due to frequency diversity can be obtained. In addition, it may be necessary to transmit a scheduling signal corresponding to the aforementioned transmission of the downlink data packet by distributed allocation in accordance with the operational requirement of the other system, regardless of the method of transmitting the downlink data packet.

However, distributed allocation is generally suitable for transmitting a downlink scheduling signal containing uplink scheduling information. If the transmission of downlink data packets to a given user equipment (UE) is rare, and the transmission of upstream data packets by this user equipment (UE) is frequent, then the base station may have difficulty in estimating the characteristics of the downlink radio channel of the user equipment (UE). In the case where the base station transmits a downstream data packet to a given user equipment (UE) by localized allocation at a point in time when the specified user equipment (UE) should transmit an upstream data packet, the base station has the ability to know the characteristics of the downlink radio channel of the user equipment (UE). In this case, in order to obtain higher transmission efficiency, it is advantageous that the downlink scheduling signal for the upstream user equipment (UE) data is transmitted in the frequency band used to carry the downlink data packet.

In view of the advantages and disadvantages explained above, and in accordance with one embodiment of the present invention, both localized allocation and distributed allocation are supported when transmitting a downlink control signal containing scheduling information for transmitting an uplink / downlink data packet. However, if downlink data is transmitted to a specific user equipment (UE), localized allocation is used to transmit the downlink control signal including uplink data scheduling information for a specific user equipment (UE). Otherwise, the downstream control signal is multiplexed and transmitted by distributed allocation.

In particular, in accordance with one embodiment of the present invention, which discusses the transmission scheme of the downward control signal, if the main time interval for transmitting the scheduling signal and the data packet in the downstream direction to each user equipment (UE) is defined as TTI (transmit time interval - interval transmission time), for transmitting a downlink scheduling signal for at least one or more OFDM symbol intervals in a range from a first OFDM symbol within a transmission time interval and (TTI) or second OFDM-symbol in the case of the first OFDM-symbol for another purpose (hereinafter represented as "from the first available character"), to a predetermined OFDM-symbol distributed allocation is used. The downstream control signal is then transmitted by localized allocation from the OFDM symbol following the indicated OFDM symbol, if necessary.

In the embodiment of the present invention explained above, distributed allocation is usually used for transmitting the downlink control signal, and localized allocation is used for the specific case when the downlink data is transmitted to the corresponding user equipment (UE). As mentioned in the description earlier, this makes it possible to more flexibly multiplex the downlink control signal using the downlink control signal transmission scheme using the OFDM symbol block. Moreover, the presence or absence of a control signal multiplexed by localized allocation or the like can be represented using a control signal indicator multiplexed by distributed allocation provided in front of the transmission time interval (TTI). Therefore, the magnitude of the control signal multiplexed by distributed resource allocation can be reduced.

FIGS. 3A and 3B illustrate downlink control signal transmission schemes for a first available OFDM symbol by distributed allocation in accordance with one embodiment of the present invention.

As mentioned in the description above, when transmitting a downlink control signal by distributed allocation for an interval ranging from the first available OFDM symbol to a given symbol, several scheduling signals can be multiplexed by distributing and allocating to at least one or more OFDM symbols in within a single transmission time interval (TTI) to transmit scheduling information on multiple data packets transmitted in the upstream or downstream direction during the corresponding its transmission time interval (TTI).

In particular, scheduling signals including a control signal 1 and a control signal 2, as shown in FIG. 3A, can be appropriately distributed using a sub-carrier block. Alternatively, scheduling signals including a control signal 1 and a control signal 2, as shown in FIG. 3B, can be respectively distributed using a group block including several subcarriers sequentially located in the frequency domain. FIG. 3B shows that four subcarriers sequentially located in the frequency domain constitute one group.

In the case where the downward control signal, as shown in Fig. 3B, is distributed over the frequency domain using a group block of subcarriers, if the number of subcarriers within the group is set equal to the number of subcarriers allocated to one resource block (RB) for transferring a data packet (e.g., 12 subcarriers in the case of a localized virtual resource block (LVRB) shown in FIG. 1) or set to integer multiple when the scheduling signal occupies part of the zone of the resource block (RB) used to transmit the data packet to According to one preferred embodiment of the present invention, an advantage is that a smaller amount of real resource block (RB) may be equally suitable.

4 is a diagram of a downlink control signal transmission by localized allocation after an OFDM symbol by distributed allocation in accordance with one embodiment of the present invention.

In accordance with the above one embodiment of the present invention, OFDM symbols that are transmitted after another OFDM symbol (other OFDM symbols) used (s) to transmit a scheduling signal by distributed allocation among OFDM symbols within a transmission time interval (TTI) are transmitted by localized scheduling signal allocation. The transmission of the downlink control signal to a specific user equipment (UE) (for example, UE1 in FIG. 4) by localized allocation during such an arbitrary transmission time interval (TTI) is applicable only if a downward data packet is transmitted to the corresponding user equipment (UE) in transmission time interval (TTI) through a localized virtual resource block (LVRB). In this case, the scheduling signal, as shown in FIG. 4, can be transmitted using portions of the localized virtual resource block zones (LVRBs) carrying downlink data packets to the corresponding user equipment (UE).

In this case, the transmission of the scheduling signal by means of distributed allocation is usually applicable with the aim of transmitting scheduling information for the transmission of the downlink data packet using a localized virtual resource block (LVRB) or a distributed virtual resource block (DVRB). However, transmitting a scheduling signal by localized allocation is applicable to transmit scheduling information for transmitting a downlink data packet using only a localized virtual resource block (LVRB).

In addition, in the embodiment of the present invention shown in FIG. 4, information on how many OFDM symbols are used to transmit the scheduling signal by distributed allocation or how many OFDM symbols are used to transmit the scheduling signal by localized allocation can be reported in common downlink in each transmission time interval (TTI) periodically or as needed.

According to the above embodiment, the transmission scheduling information of the uplink data packet is mainly carried by the transmission control signal by distributed allocation. However, in the case of an attempt to transmit scheduling information for transmitting an uplink data packet to a random user equipment (UE) when transmitting a downlink data packet to the same user equipment (UE) within an arbitrary transmission time interval (TTI), scheduling information for the uplink data packet may be transferred by the zone a resource block (RB) for transferring a data packet to a user equipment (UE), while scheduling information transmitted to the user equipment (UE) is not edachi downlink data packet transmitted by the control transmission signal by localized allocation.

In the scheduling signal transmission schemes discussed above, the information that the scheduling signal transmitted through distributed allocation carries includes the category A information about scheduling transmission of downlink data packets mentioned above, at least in connection with the prior art. In addition, this information may include Category B information about scheduling, partially or fully added to Category A information for transmitting upstream data packets.

Moreover, a scheduling signal transmitted by localized allocation may include scheduling category B information, partially or fully added to category A.

In accordance with one preferred embodiment of the present invention, the scheduling information transmitted by localized allocation of a control signal may include an indicator indicating whether said scheduling information is scheduling transmission information of a downlink data packet or scheduling information of transmission of an uplink data packet.

In the case where the scheduling information of the scheduling signal transmitted by the distributed allocation is scheduling information of the transmission of the downlink data packet, the information may include an indicator indicating whether the scheduling information of data transmission in the upstream direction is transferred to the corresponding user equipment (UE) in within the zone of a resource block (RB) for transferring a downlink channel data packet to the corresponding user equipment (UE).

In this case, as can be seen from the structure of the downward control signal in accordance with one embodiment of the present invention shown in FIG. 4, the advantage is that the corresponding user equipment (UE) makes it easier to search for scheduling information by providing a previous OFDM symbol in accordance with distributed allocation, to inform about the presence or absence of information about the planning of the transmission of the upstream data packet to the corresponding user equipment UE) for the subsequent OFDM symbol interval in accordance with localized allocation. In addition, an advantage is also that the magnitude of the control signal transmitted by the distributed allocation of resources can be reduced.

In this case, scheduling category A information transmitted to an arbitrary user equipment (UE) may include bit information to indicate resource blocks (RBs) used in transmitting the downlink data packet to the corresponding user equipment (UE) or resource blocks (RBs) used to provide the user equipment (UE) capabilities to transmit an upstream data packet. Namely, when within the same transmission time interval (TTI) there are N resource blocks (RBs), each bit within the bit information of N-bits is mapped according to the established rule to the corresponding resource block (RB) existing in the specified transmission time interval (TTI). In this case, the bit may represent information on whether the corresponding resource block (RB) is allocated for the data.

In this case, when several resource blocks (RBs) exist in a single transmission time interval (TTI), too many bits may be needed to indicate whether the corresponding resource blocks (RBs) are used by bit information. Therefore, the cost of resources for planning information may be too large.

For such a case, in accordance with one embodiment of the present invention, resource blocks (RBs) within one transmission time interval (TTI) are grouped by a predetermined number, for example, M, in accordance with a rule, and then a planned group of resource blocks (RBs) reported as bit information in lieu of a scheduled resource block (RB). Therefore, the cost of resources for planning information can be reduced. In this case, the number 'M' is an integer equal to or greater than 2, and one group of resource blocks (RBs) may include various resource blocks (RBs) in the frequency or time domain.

In the diagram explained above, a user equipment (UE) basically attempts or attempts to decode scheduling information for all possible positions of the downlink control signal transmitted by localized allocation or distributed allocation to read the scheduling information transmitted to it. If there is scheduling information containing the identifier (ID) of the corresponding user equipment (UE), the specified user equipment (UE) determines that it is transmitted scheduling information and then receives a downstream data packet or transmits an upstream data packet in accordance with the information.

In this case, there may be a different number of time-frequency resource volumes that the user equipment (UE) should try to read. This can increase the load on user equipment (UE). Therefore, it is preferable that the downstream control signal that the corresponding user equipment (UE) is trying to read is limited, as will be explained later.

Moreover, in accordance with one embodiment of the present invention, in the case where the downlink control signal is not actually carried for the OFDM symbol (s) set to provide the transmission of the downward control signal, it is proposed that downstream data should be carried for the corresponding symbol (s). This is described as follows.

5 is a diagram of a downlink data transmission to a resource unit to which a control signal is not transmitted within an OFDM symbol for transmitting a downlink control signal in accordance with one embodiment of the present invention.

First of all, the number of upstream and downstream data packets scheduled within a single transmission time interval (TTI) may vary for each transmission time interval (TTI). Therefore, the block of control signals transmitted in the downstream direction during each transmission time interval (TTI) may vary. However, if a certain number of downstream OFDM symbols is always reserved for the transmission of the downlink scheduling signal and then only used, the time-frequency resource, with the exception of the frequency domain actually carrying the scheduling signal within the reserved OFDM symbol, is consumed in the transmission time interval (TTI ) to transmit, for example, a small number of scheduling signals.

Therefore, in the above one exemplary embodiment of the present invention, there is provided a method for transmitting a downlink data packet in a time-frequency domain that has hardly succeeded in transmitting a scheduling signal within at least one or more OFDM symbols set to provide scheduling signal transmission. And the corresponding structure of the downlink signal is shown in FIG. 5.

5, one transmission time interval (TTI) is formed by 6 OFDM symbols. In this case, the first of these 6 OFDM symbols is set for use in transmitting the downlink control signal from user equipment UE1 to user equipment UE3 by distributed allocation. However, FIG. 5 shows that the remaining areas, with the exception of the area that actually carries the scheduling signal with distributed allocation within the specified OFDM symbol, are allocated to transmit the downlink data packet to the user equipment UE1.

In this case, the amount of time-frequency resource that can be allocated for data transmission through one downstream resource block (RB) may be different in each transmission time interval (TTI) depending on whether a part of the resource block (RB) is used for transmit signal scheduling with distributed allocation. Namely, as can be seen from the example shown in FIG. 5, the user equipment UE1 cannot know exactly which area within the planned resource block (RB) is used to transfer data transmitted to the user equipment UE1 if it does not know that portions of the downlink resource block areas (RBs) allocated to the data packet transmitted to the user equipment UE1 are used for a scheduling signal transmitted to another user equipment (UE2 or UE3). Thus, the user equipment UE1 cannot correctly receive the data packet.

In accordance with one embodiment of the present invention, so that user equipment units (UEs) located within a cell know which areas within OFDM symbols are set to be used for transmitting a scheduling signal during an arbitrary transmission time interval (TTI) are actually used to transmit the scheduling signal, in each transmission time interval (TTI), the base station notifies the number of scheduling signals transmitted during the transmission time interval (TTI) to the user equipments within the cell.

In this case, you can pre-decide on the selection rule for the area for transmitting the scheduling signal in accordance with the number of scheduling signals actually transmitted during each transmission time interval (TTI). Therefore, all units of the user equipment (UE) located in the cell can know which areas of the downstream time-frequency resources are used by the scheduling signals transmitted to other units of the user equipment, as well as the scheduling signals transmitted by themselves, and which time-frequency region is actually used for transmission data in each downlink resource block (RB) by the number of scheduling signals notified by the base station.

In particular, according to one embodiment of the present invention, as the number of transmitted scheduling signals increases, OFDM symbols set for use in scheduling signal transmission are used sequentially. For example, assuming that OFDM symbols are set for use in transmitting scheduling signals by using the first OFDM symbol within a transmission time interval (TTI), after fully utilizing the time-frequency resources available for transmitting the scheduling signal in the first OFDM symbol, the subsequent OFDM symbol is used according to the established rule in accordance with the increase in the number of scheduling signals. Thus, an example implementation of the allocation of the OFDM symbol for sequential transmission of control signals is shown in Fig.6. Next will be given a detailed description of the structure.

Moreover, since the number of actually transmitted scheduling signals can vary in each transmission time interval (TTI), it is preferable that the number of scheduling signals transmitted during each transmission time interval (TTI) should be broadcast on the physical channel, and not on the signal transmission channel scheduling so that all pieces of user equipment (UEs) within the cell can receive the specified number of transmitted scheduling signals.

In addition, the scheduling signal must be transmitted with high power to ensure that it is received by a user equipment (UE) located at a great distance from the base station. In this case, even if the subcarrier cannot transfer the scheduling signal within OFDM symbols carrying the scheduling signal, the largest part of the maximum transmit power provided by the base station is consumed by scheduling signals. Therefore, subcarriers may exist that may not transmit anything.

Therefore, according to one embodiment of the present invention, the base station broadcasts information including the above region (or the number of scheduling signals) used to transmit the scheduling signal, and the subcarrier region (or the number of scheduling signals corresponding to the specified region), which may not carry that or within OFDM symbols capable of carrying a downstream control signal. In this case, the user equipment units (UEs) are able to recognize the part used to transmit data within the OFDM symbol carrying the scheduling signal.

In order to achieve the same results as in the above embodiment, in another method according to one embodiment of the present invention, information about the area actually used to transmit data during the transmission time interval (TTI) within OFDM symbols capable of carrying a scheduling signal, can be transmitted directly in broadcast mode instead of providing the above base station with the ability to transmit information about the area of the transfer of the planning signal or wide atelnuyu information about the area, carrier scheduling signal, and information about the area, not carrying any information.

Therefore, in the following description, information about an area (number) of scheduling signals means information about an area carrying a scheduling signal and information about an area carrying either nothing or information about an area used to transmit data.

Moreover, instead of providing the base station with the ability to broadcast information about the area of the scheduling signal to units of user equipment (UEs) within the cell, you can also transmit information about the area of scheduling signals carried within the scheduling signal of the downstream data packet carrying data in the downstream direction to each user equipment (UE).

Namely, user equipment units (UEs) receiving data in the downstream direction need to know how many time-frequency areas are actually used for transmission by a scheduling signal during a given transmission time interval (TTI), as well as how many time-frequency areas are really used for transmission through data. Therefore, the same goal can be achieved by the way in which information about the area of the scheduling signals is included in the information carried by the downlink scheduling signal to each user equipment (UE). In this case, information about the area of scheduling signals is subjected to channel coding together with other scheduling information. Therefore, the advantage is that you can get more coding gain. However, since the same information is transmitted to each of a plurality of user equipment units (UEs) during one transmission time interval (TTI), a subsequent increase in efficiency varies depending on the number of scheduling signals transmitted during one transmission time interval (TTI) and the channel scheme coding signal scheduling. When transmitting the scheduling signal area information together with the scheduling information, it is preferable that the scheduling signal area information is included in the above category A information.

In accordance with one embodiment of the present invention, to reduce the load on a user equipment (UE) when receiving a scheduling signal and efficiently utilizing a downlink time-frequency resource, the maximum number of downlink data packets scheduled within a transmission time interval (TTI), or the maximum number of uplink packets data may be limited to a value less than the actually transmitted maximum number.

In order to achieve the same results as in the above embodiment, in another method according to one embodiment of the present invention, it is possible to impose a limit on the amount of scheduling information transmitted within the transmission time interval (TTI) of downstream data packets or the amount of scheduling information transmitted within transmission time interval (TTI) of upstream data packets.

In addition, you can impose a limit on the total amount obtained by adding the amount of scheduling information transmitted within the transmission time interval (TTI) of the upstream data packets and the amount of scheduling information transmitted within the transmission time interval (TTI) of the downlink data packets. The above maximum value (s) may be sent to the user equipment (UE) from the base station via the upper layer RRC signaling.

In a method using both a scheduling signal with distributed allocation and a scheduling signal with localized allocation according to one embodiment of the present invention, a notification scheme of user equipment units (UEs) about the number of scheduling signals and a scheme for limiting the number of scheduling signals can be applied only to the scheduling signal with distributed allocation.

In this method, if the base station broadcasts a certain number of distributed allocation scheduling signals during each transmission time interval (TTI), each user equipment (UE) tries to receive time-frequency regions preset for transmitting distributed allocation scheduling signals in accordance with the specified number only. If at the same time there is scheduling information containing the identifier (ID) of the corresponding user equipment (UE), this user equipment (UE) follows the instructions of such scheduling information.

However, since localized allocation scheduling signals are transmitted in time-frequency regions within resource blocks (RBs) carrying downlink data packets, user equipment (UEs) essentially must attempt to receive over areas transmitting localized allocation scheduling signals and are available in all resource blocks (RBs). Moreover, if the user equipment (UE) needs to make attempts to receive scheduling signals with both localized and distributed allocation, the load acting on the corresponding user equipment (UE) increases. To reduce the load acting on a user equipment (UE) when receiving a scheduling signal, in one embodiment of the present invention, the following schemes are provided.

In the first scheme, for each user equipment (UE), it is decided whether to receive a scheduling signal with distributed allocation or a scheduling signal with localized allocation. Then, the corresponding information is reported by the base station to each user equipment (UE).

The advantage of transmitting the scheduling signal to a predetermined user equipment (UE) by distributed allocation or localized allocation depends on such infrequently changing factors as the speed of movement of the user equipment (UE), the operational characteristics of the user equipment (UE), and the like. Therefore, there is no need to transmit such information frequently. And information can be transmitted to each user equipment (UE) from the base station by upper layer signaling without using a separate physical layer signal. In this case, an arbitrary user equipment (UE) attempts to receive a scheduling signal transmitted to it either by distributed allocation, or by localized allocation assigned only to the corresponding user equipment (UE).

In the second scheme, for scheduling signals transmitted by localized allocation, the user equipment (UE) attempts to receive the scheduling signal with localized allocation in one resource block (RB) (or group of resource blocks (RBs)), which is reported as having the best channel quality, or in a specific number of areas of a resource block (RB) (or group of resource blocks (RBs)) in the order that is reported as having the best channel quality, taking into account information about the quality of the downlink radio channel reported b station only base card corresponding user equipment (UE).

In the general case, each user equipment (UE) within the cell periodically or if necessary informs the base station of the downlink radio channel quality information to assist the base station in planning downlink data packets. Therefore, when transmitting downstream data packets to a given user equipment (UE) within a cell, the base station operates by using the necessary resource block (RB) (or group of resource blocks (RBs)) having the best channel quality, or one of a specific number of resource blocks (RB ) (or one of a specific number of resource block groups (RBs)) selected based on the qualities of the downlink radio channel reported by the corresponding user equipment (UE). If the base station transmits a scheduling signal with localized allocation to the corresponding area of the resource block (RB) (or group of resource blocks (RBs)), the corresponding user equipment (UE) can receive the scheduling signal with localized allocation transmitted to it according to the scheme explained above.

In this case, information on the quality of the downlink radio channel to which each user equipment (UE) should access can be limited to recently reported information or defined as a specific amount of recently reported information or as information communicated over a specific period of time from the current time. For each of these cases, the base station must appropriately determine the resource block (RB) (or group of resource blocks (RBs)) that should be used to transmit the data packet over the downlink. Also, the base station can transmit to each user equipment (UE) by signaling the upper level the number of resource blocks (RBs) or groups of resource blocks (RBs), which should be provided for receiving a scheduling signal with localized allocation in the range of information about the quality of the radio channel or one information about quality of the radio channel to which the user equipment (UE) should access.

In the third scheme, the base station notifies the resource block (RB) or group of resource blocks (RBs) that carry the scheduling signal with localized allocation to all units of user equipment (UEs) within the cell for each transmission time interval (TTI) by bitmapping.

Namely, if the number N of resource blocks (RBs) (or groups of resource blocks (RBs)) exists within one downstream transmission time interval (TTI), each bit of N-bit bitmap information is mapped to each of the resource blocks ( RBs) (or each of the resource block groups (RBs)). Also, each bit is able to reflect information indicating whether the scheduling signal is carried with localized allocation by the corresponding resource block (RB) (or a group of resource blocks (RBs)). Therefore, the user equipment (UE) reads the bitmap information for each transmission time interval (TTI), and then it can try the header of the scheduling signal with localized allocation on resource blocks (RBs) (or groups of resource blocks (RBs)) that actually carry a scheduling signal with localized allocation, without attempting to receive a scheduling signal with localized allocation on all resource blocks (RBs) (or groups of resource blocks (RBs)).

In particular, in accordance with one embodiment of the present invention, bitmap information can be broadcast for each transmission time interval (TTI) by encoding it together with information about the number of scheduling signals with a distributed allocation method.

In the fourth scheme, the downlink scheduling signal for downstream data is transmitted only by distributed allocation. The downlink scheduling signal for upstream data is transmitted by distributed allocation if there is no data to be transmitted in the downstream direction. In this case, the downlink scheduling signal for data transmitted in the upstream direction is transmitted by localized allocation within the resource blocks (RBs) (or groups of resource blocks (RBs)) if there is data to be transmitted in the downstream direction.

At least one of the above schemes is simultaneously used in the system to reduce the load on user equipment (UE) when receiving a scheduling signal.

FIG. 6 schematically illustrates a general downlink control signal transmission structure in connection with FIG. 4 and FIG. 5 according to one embodiment of the present invention.

6, one transmission time interval (TTI) includes six OFDM symbols. A portion of the subcarriers of the first and fifth OFDM symbols carry downlink pilots. In the first OFDM symbol, the number of localized allocation scheduling signals transmitted for a transmission time interval (TTI) can be broadcast in a single subcarrier distribution. In addition, bitmap information for scheduling signals with localized allocation can also be broadcast in a single subcarrier distribution in addition to the number of scheduling signals with localized allocation.

Distributed allocation scheduling signals may be transmitted with subcarrier distribution starting from the first OFDM symbol. In the example shown in FIG. 6, the first OFDM symbol and part of the second OFDM symbol are used to transmit the distributed allocation scheduling signal. 6 also shows an example of how scheduling signals of downlink data packets for user equipment UE1 are transmitted by localized allocation through a portion of a resource block (RB) area carrying downlink data packets to user equipment UE1.

Meanwhile, in one embodiment of the present invention, there is provided a scheme for supporting the interchangeability of a transmission format of planning information, which is explained in the following description.

Figure 7 presents a diagram of the change in the volume of the time-frequency resource necessary for transmitting a scheduling signal in various formats for transmitting scheduling information.

7, uplink / downlink scheduling information transmitted downstream for each transmission time interval (TTI) to each user equipment (UE) is transmitted in a scheduling signal format by proper coding and modulation. For better understanding and convenience, the coding rate (r), modulation scheme, etc., applied to the scheduling information is referred to as the “scheduling information transmission format” or the “scheduling signal transmission format”.

In this case, the state of the radio channel of the corresponding units of user equipment (UEs) within the cell may differ from one another. In particular, the conditions of the radio channel can vary significantly depending on the removal of user equipment units (UEs) from the base station or the presence or absence of obstacles. Therefore, it is inefficient to apply the same transmission format when transmitting scheduling information for all pieces of user equipment (UEs) within a cell. Preferably, different transmission formats for user equipment units (UEs) are used, respectively, depending on the state of the radio channel. If the transmission format used for scheduling information changes, then the amount of time-frequency resource needed to transmit the corresponding scheduling signal can indeed be changed. 7 shows the necessary volumes of time-frequency resources corresponding to various formats for transmitting scheduling information.

Moreover, if the base station arbitrarily selects a transmission format applicable to the scheduling information transmitted to a given user equipment (UE) for each transmission time interval (TTI), the corresponding user equipment (UE) should attempt to receive the scheduling signal in all possible transmission formats for each transmission time interval (TTI).

Therefore, in one embodiment of the present invention, there is provided a scheme for selecting a time-frequency resource volume for a transmission format applicable to scheduling information transmitted only to a specific user equipment (UE) among one or more minimum time-frequency domain units. The concept of "minimum unit of the time-frequency domain" was first proposed in provisional patent application US 60/827852 for an invention entitled "The structure of the downward control signal in a communication system using multiple carriers", invented by the author of this application, filed by the applicant of this application, and which constitutes one of the justifications for claiming the priority of this application. The indicated concept of “the minimum unit of the time-frequency domain” is adopted by the 3GPP LTE system (Third Generation Partnership Project Long Term Evolution - long-term evolution of the Third Generation Partnership Project - note translation.) As the concept of “control channel element (CCE = Control Channel Element)”. This is explained in detail below using the 3GPP LTE system as an example.

In a 3GPP LTE system, a plurality of control channel elements (CCEs) can be transmitted through the first n OFDM symbols of a subframe. In this case, the control channel element (CCE) can be considered as a transmission unit of control information, as proposed in one embodiment of the present invention. A control channel element (CCE) can be placed in a time-frequency domain in series or distributed. Each control channel element (CCE) consists of a certain number of resource elements (RE). In this case, the PDCCH (physical downlink control channel), transmitted to an arbitrary user equipment (UE) for transmitting an arbitrary subframe, can be transmitted by combining with one element of the control channel (CCE) or multiple elements of the control channel (CCE). In this case, depending on the number of control channel elements (CCEs) needed to transmit the physical downlink control channel (PDCCH), the coding rate for the corresponding physical downlink control channel (PDCCH) is determined. For example, if the coding rate is 3/4 when a physical downlink control channel (PDCCH) having information of a certain amount is transmitted through one control channel element (CCE), then it can be adjusted so that the coding rate when transmitting a physical downlink control channel ( PDCCH), having the same amount of information through two elements of the control channel (CCE), is 3/8, the coding rate when transmitting a physical downlink control channel (PDCCH) having the same amount of information, after the four control channel elements (CCEs) is 3/16, or so that the coding rate for transmitting a physical downlink control channel (PDCCH) having the same amount of information through eight control channel elements (CCEs) is 3/32.

Control channel elements (CCEs) are allocated to a user equipment (UE), which must first confirm whether a physical downlink control channel (PDCCH) transmitted to it exists. For example, under the assumption that a physical downlink control channel (PDCCH) carrying the specified information can be transmitted at a coding rate of 3/4, 3/8, 3/16 or 3/32 through one control channel element (CCE), two channel elements control (CCE), four elements of the control channel (CCE) or eight elements of the control channel (CCE), and if the specified terminal is allocated to confirm the elements of the control channel (CCE), from the first to the sixteenth, the specified terminal must decode for each element ka Control ala (CCEs) in the case of the assumption in which a physical downlink control channel (PDCCH) transmitted at a coding rate of 3/4, 3/8, 3/16 or 3/32 for sixteen control channel elements (CCEs) for each subframe. Therefore, the terminal performs a maximum of 30 (= 16 + 8 + 4 + 2) decodings to check if there is a physical downlink control channel (PDCCH) transmitted to it. This is consistent with the assumption that the physical downlink control channel (PDCCH) is mapped to a control channel element (CCE) using a tree structure only through an adjacent control channel element (CCE). If the physical downlink control channel (PDCCH) mapping becomes freer, the number of decodings that the user equipment (UE) must perform may be incremented.

To reduce the operational load on the user equipment (UE) at reception and, more specifically, to facilitate the solution of such a problem as the power consumption of the battery of the user equipment (UE) by reducing the number of decodings required to receive a physical downlink control channel (PDCCH), like to the 3GPP LTE system, one embodiment of the present invention provides a scheme for designating a transmission format of scheduling information applicable to transmit a scheduling signal to each user Yelsk equipment (UE).

In this case, the scheduling information transmission format used to transmit the scheduling signal for each user equipment (UE) can only be specifically assigned to a specific format. Alternatively, you can use the method of assigning a coding rate range in which each user equipment (UE) will attempt to receive a physical downlink control channel (PDCCH), as well as assigning a size of a group of control channel elements (CCEs) or the like.

In particular, one embodiment of the present invention provides a method for determining a maximum coding rate in a transmission format of scheduling information for each user equipment (UE) or for determining the smallest size of a group of control channel elements (CCEs).

Thus, in the case where each user equipment (UE) is declared the maximum coding rate or the minimum size of the control channel element (CCE), although the allocation is performed so that the specific user equipment (UE) checks the first to sixteenth control channel element (CCE) in the example explained above, if it is declared that the maximum coding rate at which the corresponding user equipment (UE) tries to receive a physical downlink control channel (PDCCH) is 3/8, or that the minimum size of the control channel element (CCE) group is two control channel elements (CCE), the corresponding user equipment (UE) does not need to decode one control channel element (CCE) (i.e., the case when encoding rate is 3/4), and it only performs 14 (= 8 + 4 + 2) decodings.

Thus, compared to the method for declaring a minimum coding rate or a maximum group size, a method for determining a maximum coding rate or a minimum group size of control channel elements (CCEs) for each user equipment (UE) has the following advantages.

For example, in the case of a user equipment (UE) having a maximum coding rate assigned to be 3/8, as in the example explained above, when the next channel condition worsens if scheduling information is transmitted encoded at a low coding rate, for example 3/16, corresponding to planning information can also be found. However, in the case of a user equipment (UE) having a minimum coding rate set to 3/8, when the next channel state worsens, if scheduling information is transmitted encoded at a much lower coding rate, for example 3/16, it becomes difficult to detect the corresponding scheduling information . Namely, as in the present embodiment, the method of determining the maximum coding rate or the minimum size of a group of control channel elements (CCEs) applicable for transmitting scheduling information can cope with the case of a low coding rate due to subsequent degradation of the channel characteristics more efficiently, than a method for determining the minimum coding rate or the maximum size of a group of control channel elements (CCEs).

For the same purpose as in the above embodiment, in another embodiment of the present invention, it is proposed that the base station notifies each user equipment (UE) of a maximum coding rate (or the smallest size of a group of control channel elements (CCEs)) at which the corresponding user equipment (UE) will attempt to receive the physical downlink control channel (PDCCH).

In particular, as noted in the previous description of the above example, even if one user equipment (UE) is assigned to check the first to sixteenth elements of a control channel (CCE), if it is announced that the maximum coding rate at which the corresponding user equipment (UE) will be attempting to receive a physical downlink control channel (PDCCH) is 3/8 (or that the minimum size of a group of control channel elements (CCEs) is two control channel elements (CCEs)) and that the minimum coding rate is 3/16 (or that the maximum size of a group of control channel elements (CCEs) has four control channel elements (CCEs)), there is no need for user equipment (UE) to decode assuming one control channel element (CCE) (case when the coding rate is 3/4) and decoding under the assumption of eight elements of the control channel (CCE) (the case when the coding rate is 3/32), and it performs only a maximum of 12 (= 8 + 4) decodings.

For the same purpose as in the above embodiment, in another embodiment of the present invention, it is proposed that the base station notifies each user equipment (UE) of whether the corresponding user equipment (UE) is trying to receive a physical downlink control channel (PDCCH) at the maximum coding rate (or the smallest size of the group of control channel elements (CCEs)), at which the corresponding user equipment (UE) will try to receive fi downlink control channel (PDCCH), and for a given number of coding rates that are lower than the previous coding rate (or for a given number of group sizes greater than the smallest group size of control channel elements (CCEs)).

In particular, as was noted in the previous description of the above example, even if one user equipment (UE) is assigned to check the first to sixteenth elements of the control channel (CCE), if the two-stage encoding rates, including the maximum encoding rate of 3/8 and the encoding rate of more than 3 / 8, in which the corresponding user equipment (UE) will attempt to receive a physical downlink control channel (PDCCH) (or two-stage groups of control channel elements (CCEs)), will complement They are clearly declared to be validated by the corresponding user equipment (UE), the specified user equipment (UE) does not need to be decoded on the assumption of one control channel element (CCE) (the case when the coding rate is 3/4) and decoding on the assumption of eight control channel elements ( CCE) (the case when the encoding rate is 3/32), and it performs only a maximum of 12 (= 8 + 4) decodings.

Using the methods explained above, it is possible to reduce the number of trial decodings for the user equipment (UE) to receive a physical downlink control channel (PDCCH). Therefore, a problem such as user equipment (UE) battery power consumption and the like can be solved.

In the embodiments explained above, the format for transmitting scheduling information for each of the user equipment units (UEs) does not require frequent changes. Therefore, this information can be brought by the base station to each user equipment (UE) by signaling the upper level located above the physical layer. In addition, each of the user equipment units (UEs) may attempt to receive a scheduling signal based on the assumption of a transmission format assigned to the corresponding user equipment (UE) itself. At the same time, the user equipment (UE) searches for the time-frequency domain of the downstream direction, which carries the scheduling signal, for the indicated scheduling signal by the unit of the volume of the time-frequency resource defined for the transmission of the planning information to the user equipment (UE) itself.

According to a detailed embodiment of the present invention, the operation of a user equipment (UE) when receiving a scheduling signal can be further simplified by assigning the amount of time-frequency resource used to transmit scheduling information in various transmission formats to an integer multiple of the smallest amount of time-frequency resource used to transmit planning information.

In this case, the volume of the smallest time-frequency resource used in transmitting scheduling information may correspond to the control channel element (CCE) explained above. Namely, in the present embodiment, it is proposed to set the amount of the time-frequency resource used in scheduling information different in the transmission format for the control channel element (CCE) block. As mentioned in the previous description, the control channel element (CCE) may include a serial section in the time-frequency domain or it may have a shape distributed over the time-frequency domain.

FIGS. 8A and 8B schematically show examples of how user equipment units (UEs) having different scheduling information transmission formats assigned to them search for scheduling signals in accordance with one embodiment of the present invention.

In particular, FIGS. 8A and 8B show examples where two pieces of user equipment (UEs) that are assigned different scheduling information transmission formats search for scheduling signals using the schemes explained above in the case where scheduling signals are carried by subcarriers, adjacent to the frequency axis for arbitrary symbols, or in the case where scheduling signals are transmitted by a block of distributed subcarriers.

8A and 8B, the user equipment UE1 and the user equipment UE2 respectively receive the scheduling information transmission formats assigned to them, and then they respectively try to receive scheduling signals in possible time-frequency domains. In particular, the user equipment UE1 receives a single frequency domain indicated by one gap in FIG. 8A, and then it attempts to receive a scheduling signal. And the user equipment UE2 receives the unit frequency domain indicated by the two gaps in Fig. 8B, and then tries to receive the scheduling signal. In this case, the user equipment UE1 in the example shown in FIG. 8A can complete the search for the scheduling signal by reading the scheduling signal transmitted to it during the fourth search.

In the method in which the base station broadcasts the number of distributed allocation scheduling signals actually transmitted for each transmission time interval (TTI), in accordance with one embodiment of the present invention, the operation explained above can be supported by using the smallest amount of frequency a temporary resource used to transmit scheduling signals with distributed allocation as a unit volume instead of using the number of scheduling signals distributed distribution, and then by subsequent notification of the amount of time-frequency resources reaching specified unit volumes used to transmit planning signals with distributed allocation.

In another method, in accordance with one embodiment of the present invention, it is possible to reduce the load on a user equipment (UE) when receiving a scheduling signal by notifying the number of distributed allocation scheduling signals actually transmitted for each transmission time interval (TTI), which should be allocated for each scheduling signal having a different transmission format. In this case, priority is assigned before allocating the time-frequency domain for transmitting the scheduling signal to each format for transmitting scheduling information.

Fig. 9 schematically shows an example in which user equipment units (UEs) having transmission formats assigned to them search for scheduling signals if different scheduling information transmission formats have different priorities.

According to Fig. 9, there are two transmission formats: transmission format 1 and transmission format 2. Moreover, the scheduling signal in transmission format 1 takes precedence over another scheduling signal in transmission format 2 in the allocation of the time-frequency domain. In this case, as shown in the example of FIG. 9, three scheduling signals in transmission format 1 and two scheduling signals in format 2 are transmitted.

When periodically transmitting scheduling signals according to the rule of the example shown in Fig. 9, if the user equipment (UE) is aware of this rule in advance or if the base station notifies you of the number of scheduling signals transmitted in one transmission format, the corresponding user equipment (UE) recognizes which time-frequency domain carries the scheduling signal in the same transmission format assigned to it. Therefore, the corresponding user equipment (UE) may attempt to receive the scheduling signal only in the corresponding area.

INDUSTRIAL APPLICABILITY

Therefore, in accordance with one exemplary embodiment of the present invention, a downlink control signal transmission method helps to ensure both transmission efficiency by localized allocation and gain due to frequency diversity in distributed allocation by taking into account the advantages and disadvantages of localized allocation and distributed allocation.

Moreover, due to the transmission structure of the downward control signal using localized allocation and distributed allocation, a transmission signal is provided by a common distributed allocation to the front of a single transmission time interval (TTI), and a transmission signal is provided by localized allocation to the back of a corresponding transmission time interval ( TTI). Therefore, the present invention flexibly copes with the size of the control signal. In this case, the indicator of control information included in the distributed allocation or the like is included in the part by localized allocation, due to which the reception efficiency can be improved.

The present invention has been described and illustrated here with reference to preferred examples of its implementation. It will be apparent to those skilled in the art that various modifications and changes can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided that they fall within the scope of the appended claims and their equivalents.

Claims (13)

1. A method for transmitting a downlink control signal by a base station, comprising:
determining a transmission format for the downlink control signal including scheduling information for transmitting data in upstream or downstream directions; and
transmitting a downlink control signal to each user equipment in accordance with a transmission format of the downlink control signal,
wherein the transmission format of the downward control signal is set so that the downward control signal is transmitted by a block from an integer multiple of the smallest dimensional unit of the time-frequency domain used to transmit the downward control signal. 2. The method according to claim 1, in which the smallest unit of time-frequency domain used to transmit the downward control signal is sequentially located within the time-frequency domain. 3. The method according to claim 1, in which the smallest unit of time-frequency domain used to transmit the downward control signal is located distributed within the time-frequency domain. 4. The method according to claim 1, in which the smallest unit of time-frequency domain used to transmit the downward control signal is an element of the control channel containing a given number of resource elements. 5. The method according to claim 4, in which the transmission format of the downward control signal comprises transmission formats for the downward control signals, each of which determines that the downward control signal is transmitted by a block of one, two, four and eight elements of the control channel, respectively. 6. The method according to claim 1, wherein the scheduling information for transmitting data in upward or downward directions contains information about a bitmap in a block from a group of resource blocks, wherein the group of resource blocks contains a predetermined number of resource blocks. 7. The method according to claim 1, in which the transmission format of the downward control signal is determined in accordance with the status of the channel for each user equipment. 8. A method of receiving a downward control signal by user equipment, comprising:
receiving from the base station a downward control signal including scheduling information for transmitting data in upward or downward directions, wherein the downward control signal is transmitted by the base station in a block from an integer multiple of the smallest unit of time-frequency domain used to transmit the downward control signal; and
decoding the downstream control signal in the specified block. 9. The method of claim 8, in which the smallest unit of time-frequency domain used to transmit the downward control signal is sequentially located within the time-frequency domain. 10. The method of claim 8, in which the smallest unit of time-frequency domain used to transmit the downward control signal is located distributed within the time-frequency domain. 11. The method of claim 8, in which the smallest unit of time-frequency domain used to transmit the downward control signal is an element of the control channel containing a given number of resource elements. 12. The method according to claim 11, in which the user equipment decodes the downward control signal in a block of one, two, four or eight elements of the control channel. 13. The method of claim 8, wherein the scheduling information for transmitting data in upward or downward directions contains information about a bitmap in a block from a group of resource blocks, wherein the group of resource blocks contains a predetermined number of resource blocks.

Images