CN102404797B - The transmission of CFI information and acquisition methods and sending and receiving device in LTE system - Google Patents

Abstract

The present application provides a method for transmitting and acquiring CFI information in an LTE system, and a sending and receiving device in the LTE system. The method for transmitting CFI information includes: setting CFI information for subframes in the MIB period; carrying the CFI information in MIB information corresponding to the MIB period; and transmitting the MIB information through a PBCH channel. In this way, the CFI information can be carried in the MIB information and transmitted through the PBCH channel.

Description

Method for transmission and acquisition of CFI information in LTE system, and sending and receiving device

technical field

The present application relates to the technical field of wireless communication, and in particular to the Long Term Evolution (LTE) system.

Background technique

Four downlink physical control channels are defined in the Long Term Evolution (LTE, Long Term Evolution) system: Physical Broadcast Channel (PBCH, Physical Broadcast Channel), Physical Control Format Indicator Channel (PCFICH, Physical Control Format Indicator Channel), Physical Downlink Control Channel ( PDCCH, Physical Downlink ControlChannel) and physical HARQ indicator channel (PHICH, Physical HARQ IndicatorChannel).

The PBCH channel is used to transmit the physical broadcast channel of the Master Information Block (MIB). The MIB information transmitted in the PBCH channel includes: downlink bandwidth, PHICH configuration, system frame number (SFN), reserved bits, etc.

The PCFICH channel is used to carry a Control Format Indicator (CFI, Control Format Indicator). The CFI information is used to indicate the number of OFDM symbols occupied by control fields such as downlink control information (DCI).

The PHICH channel is used for uplink transmission of ACK/NACK feedback information of hybrid automatic repeat request.

The PDCCH channel is used to carry scheduling allocation and other control information, that is, the PDCCH channel is a channel for carrying downlink control information DCI.

In the existing LTE system design, as shown in FIG. 1 , the MIB information transmitted in the physical broadcast channel PBCH uses a fixed scheduling with a period of 40 ms and a retransmission mode within 40 ms. A 40ms MIB period includes four 10ms radio frames, and one radio frame includes 10 subframes, that is, a MIB period may include 40 subframes. In the LTE system, the control domain (including PCFICH channel, PHICH channel and PDCCH channel) and service domain (including physical downlink shared PDSCH channel) of a subframe are carried in the subframe in a resource sharing manner, and are sent every 1 ms. Wherein, the total number of OFDM (Orthogonal Frequency Division Multiplexing) symbols occupied by the control domain and the service domain in the normal mode is 14. The CFI information transmitted through the PCFICH channel indicates the number of OFDM symbols occupied by the control domain. When the control domain occupies less resources, more resources are allocated to the service domain, and vice versa. For a system with a number of RBs greater than 10, the value of the CFI is 1/2/3, which means that the number of OFDM symbols occupied by the control domain can be 1-3. For a system with a number of RBs less than 10, the value of CFI is 1/2/3/4, which means that the number of OFDM symbols occupied by the control domain can be 1-4. That is to say, in the prior art, CFI information is transmitted through the PCFICH channel for each subframe, so as to dynamically allocate resources between the control domain and the service domain.

However, since the CFI information needs to be transmitted in the PCFICH channel of each subframe, resources in the control domain are occupied. In particular, for M2M services with a small amount of data carried by the LTE system, such as electricity meter data reporting, etc., since the number of terminals running such services in the system may be very large, a large amount of control channel resources will be occupied, and it is very easy to cause PDCCH channel congestion. Condition. Therefore, it is necessary to increase the capacity of the PDCCH channel to alleviate the problem of limited capacity of the PDCCH channel encountered when the LTE system supports services with a large number of users and a small amount of data.

Contents of the invention

The purpose of this application is to provide a method for transmitting and acquiring CFI information in an LTE system, so as to avoid problems such as channel congestion caused by transmitting CFI information in each subframe.

According to one aspect of the present application, a method for transmitting CFI information in an LTE system is provided, including: setting CFI information for subframes in a MIB cycle; carrying the CFI information in the MIB information corresponding to the MIB cycle ; and transmit the MIB information through a PBCH channel. In this way, the CFI information can be carried in the MIB information and transmitted through the PBCH channel. The set CFI information can indicate the number of OFDM symbols occupied by the control field of the subframe in the MIB period.

According to an embodiment, the PCFICH channel used to transmit the CFI information in the subframe may be deleted. In this way, excessive occupancy of subframe control field resources caused by transmitting CFI information in each subframe is avoided.

According to an embodiment, the resources of the deleted PCFICH channel in the subframe may be used for the PDCCH channel of the subframe. In this way, the capacity of the PDCCH channel can be effectively increased, and the problem of limited PDCCH channel capacity encountered when the LTE system supports services with a large number of users and a small amount of data can be alleviated.

According to another embodiment, the same CFI information may be set for subframes in one MIB period.

According to another implementation manner, the CFI information may be carried in a reserved bit in the MIB information. Optionally, the CFI information is carried in an extension bit in the MIB information.

According to another aspect of the present application, a method for obtaining CFI information in an LTE system is provided, including: receiving MIB information carrying CFI information through a PBCH channel; obtaining the CFI information carried in the MIB information; and The CFI information is used to indicate the number of OFDM symbols occupied by the control field of the subframe in the MIB period corresponding to the MIB information.

According to an embodiment, the step of obtaining the CFI information carried in the MIB information may include: parsing the reserved bits in the MIB information, and obtaining the CFI information carried in the reserved bits of the MIB information.

According to an embodiment, the step of obtaining the CFI information carried in the MIB information may include: parsing the extension bits in the MIB information, and obtaining the CFI information carried in the MIB information extension bits.

According to another aspect of the present application, a sending device in an LTE system is provided, including: a setting module for setting CFI information for subframes in an MIB cycle; a processing module for carrying the CFI information on the In MIB information corresponding to the MIB period; and a sending module, transmitting the MIB information through a PBCH channel.

According to an embodiment, the processing module deletes the PCFICH channel used to transmit the CFI information in the subframe.

According to another implementation manner, the processing module uses the resources of the deleted PCFICH channel in the subframe for the PDCCH channel of the subframe.

According to another embodiment, the setting module sets the same CFI information for subframes in one MIB period.

According to another aspect of the present application, a receiving device in an LTE system is provided, including: a receiving module that receives MIB information carrying CFI information through a PBCH channel; and an obtaining module that obtains the CFI information carried in the MIB information .

According to an embodiment, the receiving device further includes a processing module, the processing module applies the CFI information obtained by the obtaining module to indicate the number of OFDM symbols occupied by the control field of the subframe in the MIB period corresponding to the MIB information.

Description of drawings

FIG. 1 shows the MIB cycle in the downlink of the LTE system.

Fig. 2 shows a flowchart of a method for transmitting CFI information in an LTE system according to the present application.

Fig. 3 shows a flowchart of a method for acquiring CFI information in an LTE system according to the present application.

Fig. 4 shows a block diagram of a sending device in an LTE system according to the present application.

Fig. 5 shows a block diagram of a receiving device in an LTE system according to the present application.

Detailed ways

The method for transmitting and acquiring CFI information in the LTE system disclosed in the present application will be described in detail below with reference to the accompanying drawings.

Fig. 2 shows a transmission method of CFI information in an LTE system according to the present application.

As shown, in step 210, CFI information is set for subframes in the MIB period. As mentioned above, one MIB period includes multiple subframes. According to an embodiment of the present application, CFI information can be set for subframes in one or more MIB periods. The set CFI information can indicate the number of OFDM symbols occupied by the control field of the subframe in one or more MIB periods.

In step 220, the set CFI information is carried in the MIB information corresponding to the MIB period.

In step 230, the MIB information is transmitted through a physical broadcast channel PBCH.

In this way, the CFI information can be set for the subframes in the MIB period, and the CFI information can be carried in the MIB information corresponding to the MIB period, and transmitted through the PBCH channel.

According to an implementation manner, the PCFICH channel used to transmit CFI information in the subframe may be deleted. Therefore, the control field of each subframe in the LTE system only includes the PHICH channel and the PDCCH channel. In this way, excessive occupancy of subframe control domain resources caused by transmitting CFI information through the PCFICH channel in each subframe is avoided.

In addition, when the LTE system supports services with a large amount of users and a small amount of data, it is usually necessary to use more resources for the PDCCH channel in the control domain to indicate user information. According to an embodiment of the present application, the resources of the deleted PCFICH channel in the subframe may be used for the PDCCH channel of the subframe. In this way, the resources occupied by the PDCCH channel can be effectively increased, and the problem of PDCCH congestion can be solved, especially the problem of limited PDCCH channel capacity encountered in large user volume and small data volume services under the LTE system.

According to one embodiment, the same CFI information is set for subframes in one MIB period. That is to say, for each subframe in the same MIB period, the number of OFDM symbols occupied by the control field is the same, and the CFI information carried in the MIB is applicable to all subframes in the MIB period. For example, one MIB period as shown in FIG. 1 includes 40 subframes. One piece of CFI information can be set for 40 subframes of this MIB period, and the value of CFI is 4, which indicates that the number of OFDM symbols occupied by the control field of 40 subframes in this MIB period is all 4.

As mentioned above, the MIB information includes: downlink bandwidth, PHICH configuration, system frame number (SFN), reserved bits, etc. According to an embodiment, the set CFI information can be carried in a reserved bit in the MIB information.

According to another embodiment, the set CFI information can be carried in the extension bit in the MIB information. That is, the existing MIB information is expanded, and the CFI information is added in addition to the existing MIB information. The expanded MIB information includes: downlink bandwidth, number of transmit antennas, PHICH configuration, system frame number (SFN), CFI information, reserved bits, etc.

The transmission method of the present application will be specifically described below by taking an LTE system supporting 6RB (resource block) as an example.

In the LTE system mode supporting 6RB, the maximum value of CFI is 4, that is, a maximum of 4 OFDM symbols can be used to carry control domain information. According to the LTE system resource setting principle, the 4 OFDM symbols in the LTE system with 6 RBs contain at most 66 REGs (ResourceElement Group).

In the prior art, the control domain includes PCFICH channel, PHICH channel and PDCCH channel. According to the physical channel mapping principle in the LTE system, the PCFICH channel needs to occupy 4 REGs, and the PHICH channel needs to occupy 3 REGs (assuming that the PHICH Group is configured as 1), so the number of RGEs that can provide PDCCH channels in this system is 59. According to the PDCCH mapping rule, the resource unit for bearing the PDCCH is a CCE, and each CCE is composed of 9 REGs. Therefore, in an LTE system including 6RB, there are at most 6 CCEs. According to the principle of carrying PDCCH, the common search space (Common search space) occupies at least 4 CCEs, so the resources of PDCCH in the specific mobile terminal search space (UE specific search space) used to carry PDSCH and PUSCH resource indication information are relatively limited. It is easy to cause PDCCH congestion, and this problem will be more prominent when the system supports a large number of users.

According to the present application, in the LTE system including 6RB, the PCFICH channel in each subframe is deleted, and the CFI information is carried in the MIB information transmitted through the physical broadcast channel PBCH. The resources occupied by the PCFICH channel are used for the PDCCH channel, so that the REG resources that can be used by the PDCCH channel are increased from 59 to 63, that is, the number of CCEs that can be used by the PDCCH is increased from 6 to 7, and the CCE resources are increased by about 16%. Therefore, this method can effectively alleviate the problem of limited PDCCH resources.

In addition, since the CFI information is carried in the MIB information, and the update period of the MIB information is 40ms, this means that the OFDM symbols occupied by the PDCCH can be updated at a speed of 40ms, so the resources occupied by the PDSCH area can be adjusted at least every 40ms , especially in a network with small data volume services as the main business, such an update speed can meet actual needs.

Fig. 3 shows a method for obtaining CFI information by a terminal device in an LTE system according to the present application. As shown in the figure, in step 301, MIB information carrying CFI information is received through a physical broadcast channel PBCH. In step 302, the CFI information carried in the MIB information is obtained. In step 303, the CFI information is applied to the subframe of the MIB period corresponding to the MIB information, that is, the CFI information is applied to indicate the number of OFDM symbols occupied by the control field of the subframe of the MIB period corresponding to the MIB information .

In this way, the CFI information can be obtained by receiving the MIB information, and the CFI information can be applied to all subframes in the MIB cycle, which avoids the need for the terminal device to parse and obtain the CFI information when receiving each subframe, and reduces the calculation amount of the terminal device , Save system resources.

According to an embodiment, step 320 further includes: parsing the reserved bits in the MIB information, and obtaining the CFI information carried in the reserved bits of the MIB information.

According to another embodiment, step 320 further includes: parsing the extension bits in the MIB information, and obtaining the CFI information carried in the MIB information extension bits.

Fig. 4 shows a block diagram of a sending device in an LTE system according to the present application. As shown in the figure, the sending device in the LTE system includes a setting module 410 , a processing module 420 and a sending module 430 . The configuration module 410 configures CFI information for subframes in the MIB period. The processing module 420 carries the CFI information in the MIB information corresponding to the MIB period. The sending module 430 transmits the MIB information through the PBCH channel.

According to an embodiment, the processing module 420 may delete the PCFICH channel used to transmit CFI information in the subframe. Optionally, the processing module 420 may use the resources of the deleted PCFICH channel in the subframe for the PDCCH channel of the subframe.

According to an embodiment, the setting module 410 can set the same CFI information for subframes in one MIB period.

Fig. 5 shows a block diagram of a receiving device in an LTE system according to the present application. As shown in the figure, the receiving device in the LTE system includes a receiving module 510 and an acquiring module 520 . The receiving module 510 receives the MIB information carrying the CFI information through the PBCH channel. The obtaining module 520 obtains the CFI information carried in the MIB information.

According to an embodiment, the receiving device 500 may further include a processing module 530 . The processing module 530 applies the CFI information obtained by the obtaining module to the number of OFDM symbols occupied by the control field of the subframe indicating the MIB period corresponding to the MIB information.

The exemplary embodiments of the present application are described above with reference to the accompanying drawings. It should be understood by those skilled in the art that the above-mentioned embodiments are only examples for the purpose of illustration, and are not used for limitation. Any modifications, equivalent replacements, etc. All should be included in the protection scope of this application.

Claims (4)

1. A transmission method of CFI information in an LTE system, comprising: Setting the same CFI information for subframes in a MIB period, the CFI information indicating the number of OFDM symbols occupied by the control field of the subframe in the MIB period corresponding to the MIB information; carrying the CFI information in a reserved bit or an extended bit in the MIB information corresponding to the MIB period; transmitting the MIB information through a PBCH channel; deleting the PCFICH channel used to transmit the CFI information in the subframe; and The resources of the deleted PCFICH channel in the subframe are used for the PDCCH channel of the subframe. 2. A method for obtaining CFI information in an LTE system, comprising: receiving MIB information carrying CFI information through the PBCH channel, the CFI information indicating the number of OFDM symbols occupied by the control domain of the subframe in the MIB period corresponding to the MIB information; and Analyzing the reserved bits or extended bits in the MIB information, and obtaining the CFI information carried in the reserved bits or extended bits of the MIB information; Delete the PCFICH channel used to transmit the CFI information in the subframe, and use the resources of the deleted PCFICH channel in the subframe for the PDCCH channel of the subframe. 3. A sending device in an LTE system, comprising: The setting module is configured to set the same CFI information for subframes in a MIB period, and the CFI information indicates the number of OFDM symbols occupied by the control field of the subframe in the MIB period corresponding to the MIB information; A processing module, carrying the CFI information in a reserved bit or an extended bit in the MIB information corresponding to the MIB period; and A sending module, transmitting the MIB information through a PBCH channel; Wherein, the processing module deletes the PCFICH channel used to transmit the CFI information in the subframe, and uses the resources of the deleted PCFICH channel in the subframe for the PDCCH channel of the subframe. 4. A receiving device in an LTE system, comprising: The receiving module receives the MIB information bearing the CFI information through the PBCH channel; An acquiring module, configured to acquire CFI information carried in the MIB information; and A processing module, the processing module applies the CFI information obtained by the obtaining module to indicate the number of OFDM symbols occupied by the control field of the subframe in the MIB cycle corresponding to the MIB information, and deletes the number of OFDM symbols used to transmit the The PCFICH channel of the CFI information, and use the resources of the deleted PCFICH channel in the subframe for the PDCCH channel of the subframe.