113 may be connected to the antenna 115. The transceiver 113 includes a transmitter Tx and a receiver Rx. Specifically, the one or more antennas 115 may receive the radio frequency signal. The receiver Rx of the transceiver 113 is configured to: receive the radio frequency signal from the antenna, convert the radio frequency signal into a digital baseband signal or a digital intermediate frequency signal, and provide the digital baseband signal or the digital intermediate frequency signal for the processor 111, so that the processor 111 further processes the digital baseband signal or the digital intermediate frequency signal, for example, performs demodulation processing and decoding processing. In addition, the transmitter Tx of the transceiver 113 is further configured to: receive a modulated digital baseband signal or digital intermediate frequency signal from the processor 111, convert the modulated digital baseband signal or digital intermediate frequency signal into a radio frequency signal, and send the radio frequency signal through the one or more antennas 115. Specifically, the receiver Rx may selectively perform one or more levels of frequency down-mixing processing and analog-to-digital conversion processing on the radio frequency signal to obtain the digital baseband signal or the digital intermediate frequency signal. A sequence of the frequency down-mixing processing and the analog-to-digital conversion processing is adjustable. The transmitter Tx may selectively perform one or more levels of frequency up-mixing processing and digital-to-analog conversion processing on the modulated digital baseband signal or digital intermediate frequency signal to obtain the radio frequency signal. A sequence of the frequency up-mixing processing and the digital-to-analog conversion processing is adjustable. The digital baseband signal and the digital intermediate frequency signal may be collectively referred to as digital signals.

The transceiver 113 may also be referred to as a transceiver unit, a transceiver, a transceiver apparatus, or the like. Optionally, a component in the transceiver unit for implementing a receiving function may be considered as a receiving unit. A component in the transceiver unit for implementing a sending function may be considered as a sending unit. That is, the transceiver unit includes the receiving unit and the sending unit. The receiving unit may also be referred to as a receiver, an input port, a receiving circuit, or the like. The sending unit may be referred to as a transmitter, a transmitter, a transmitting circuit, or the like.

FIG. 3 is a schematic diagram of a structure of a terminal device according to an embodiment of this application. Reference may be made to FIG. 3 for the structure of the terminal device.

The terminal device includes at least one processor 211, at least one transceiver 212, and at least one memory 213. The processor 211, the memory 213, and the transceiver 212 are connected to each other. Optionally, the terminal device may further include an output apparatus 214, an input apparatus 215, and one or more antennas 216. The antenna 216 is connected to the transceiver 212, and the output apparatus 214 and the input apparatus 215 are connected to the processor 211.

The transceiver 212, the memory 213, and the antenna 216 may implement similar functions with reference to the related description in FIG. 2.

The processor 211 may be a baseband processor or a CPU. The baseband processor and the CPU may be integrated or separated.

The processor 211 may be configured to implement various functions for the terminal device. For example, the processor is configured to process a communication protocol and communication data; or is configured to control the entire terminal device, execute a software program, and process data of the software program; or is configured to assist in completing a computing processing task, for example, graphics, image, or audio processing. Alternatively, the processor 211 is configured to implement one or more of the foregoing functions.

The output apparatus 214 communicates with the processor 211 to display information in a plurality of manners. For example, the output apparatus 214 may be a liquid crystal display (liquid crystal display, LCD), a light emitting diode (light emitting diode, LED) display device, a cathode ray tube (cathode ray tube, CRT) display device, a projector (projector), or the like. The input apparatus 215 communicates with the processor 211 to receive user input in a plurality of manners. For example, the input apparatus 215 may be a mouse, a keyboard, a touchscreen, a sensor, or the like.

A receive filter and a transmit filter of each of dual duplexers in a related technology each have a bandwidth of 30 MHz. However, a maximum downlink bandwidth that can be allocated in spectrum allocation of China broadcasting network (China broadcasting network, CBN) is 40 MHz. To provide a highest downlink peak rate for user equipment as far as possible, a bandwidth of a downlink band can be configured as large as possible. However, the dual duplexers used in the related technology can only support symmetrical uplink and downlink bandwidths up to 30 MHz, and a bandwidth configuration of an uplink band is consistent with that of a downlink band. Because an uplink signal sent by user equipment mainly includes signaling and a small amount of data, the sending usually can be completed without a large bandwidth. If an uplink bandwidth and a downlink bandwidth with a same bandwidth size are allocated, a waste of uplink spectrum resources may be caused, or a downlink spectrum is limited by the duplexer to allocate only a 30 MHz bandwidth at most at a time, and some downlink spectrum resources cannot be allocated, thereby reducing a utilization of spectrum resources. In addition, when an uplink bandwidth and a downlink bandwidth with a same bandwidth size are allocated and the bandwidth is relatively large, it is difficult to meet a requirement on protection of an out-of-band spurious index of a DTV.

In this embodiment of this application, it is proposed to consider asymmetric uplink and downlink bandwidths in spectrum allocation, and an uplink spectrum and a downlink spectrum are decoupled, for example, the bandwidth of the uplink band is allocated 30 MHz, and the bandwidth of the downlink band is allocated 40 MHz. Based on this allocation solution, an embodiment of this application provides a communication apparatus, which is used to support transceiving filtering when the uplink bandwidth and the downlink bandwidth are asymmetric.

An embodiment of this application provides a communication apparatus, and the communication apparatus may be applied to the transceiver 212 of the foregoing terminal device. FIG. 4 is a schematic diagram of a structure of a communication apparatus according to Embodiment 1 of this application. As shown in FIG. 4, the communication apparatus may include: a first duplexer 41, a second duplexer 42, and a first switch 43. A first output end 431 of the first switch 43 is connected to an input end of the first duplexer 41, and a second output end 432 of the first switch 43 is connected to an input end of the second duplexer 42. When the first switch 43 is switched to the first output end 431, a branch at which the first duplexer 41 is located is connected. When the first switch 43 is switched to the second output end 432, a branch at which the second duplexer 42 is located is connected. A transmit filter 411 of the first duplexer 41 corresponds to a first uplink band, a receive filter 412 of the first duplexer 41 corresponds to a first downlink band, and a bandwidth of the first downlink band is greater than that of the first uplink band. A transmit filter 421 of the second duplexer 42 corresponds to a second uplink band, a receive filter 422 of the second duplexer 42 corresponds to a second downlink band, and a bandwidth of the second downlink band is greater than that of the second uplink band.

Optionally, the first downlink band and the second downlink band have a same bandwidth. That the first downlink band and the second downlink band have a same bandwidth may be understood as that the first downlink band and the second downlink band have the same bandwidth, but frequency positions of the two bands are different. For example, the first downlink band is 758-803 MHz, and the second downlink band is 703-748 MHz. The two bands each have a bandwidth of 45 MHz, but the second downlink band is located in a low-frequency position, while the first downlink band is located in a high-frequency position. That the first downlink band and the second downlink band have a same bandwidth may alternatively be understood as that the first downlink band and the second downlink band have the same bandwidth and position. For example, the first downlink band and the second downlink band are 758-803 MHz and have a bandwidth of 45 MHz.

Preferably, the first uplink band may be 703-733 MHz with a bandwidth of 30 MHz, the second uplink band may be 718-748 MHz with a bandwidth of 30 MHz, and the first downlink band and the second downlink band may be 758-803 MHz with a bandwidth of 45 MHz.

In a possible implementation, the receive filter 412 of the first duplexer 41 and the receive filter 422 of the second duplexer 42 are full-bandwidth filters. The full bandwidth may be understood as the entire downlink bandwidth that matches a communication standard supported by a communication system.

The communication apparatus is provided with the two duplexers, the transmit filters of the two duplexers are arranged to correspond to two different uplink bands respectively, and the receive filters of the two duplexers are arranged to correspond to two downlink bands respectively. In the same duplexer, the downlink band corresponding to the receive filter is greater than the uplink band corresponding to the transmit filter. Therefore, no matter which branch at which one of the two duplexers is located is connected by the switch, transceiving filtering can be implemented when an uplink bandwidth a downlink bandwidth are asymmetric, such as uplink and downlink asymmetric bandwidths of a 700 MHz band (n28). In this way, when the communication apparatus according to this embodiment of the present invention is applied, the downlink bandwidth is not limited by a size of the uplink bandwidth. In a scenario in which the downlink bandwidth is greater than the uplink bandwidth, spectrum resources of the downlink bandwidth can be fully used, thereby improving a utilization of spectrum resources. In addition, in each of the dual duplexers according to this embodiment of the present invention, a larger downlink band can provide a higher downlink peak rate for user equipment, and a smaller uplink band can ensure that a requirement on protection of an out-of-band spurious index of a digital TV DTV can be met.

Based on the communication apparatus shown in FIG. 4, FIG. 5 is a schematic diagram of a structure of a communication apparatus according to Embodiment 2 of this application. As shown in FIG. 5, the communication apparatus may further include: a power amplifier (power amplifier, PA) 51, a second switch 52, and an antenna 53. An output end of the PA 51 is connected to an input end of the first switch 43. An output end of the first duplexer 41 is connected to a first input end 521 of the second switch 52, and an output end of the second duplexer 42 is connected to a second input end 522 of the second switch 52. An output end of the second switch 52 is connected to the antenna 53.

In the communication apparatus, the PA 51 amplifies power of a signal and then transmits the signal to the first duplexer 41 or the second duplexer 42, and then the signal is transmitted to the antenna 53 by cooperating with the second switch 52. When the first switch 43 is switched to the first output end 431 and the second switch 52 is switched to the first input end 521, the branch at which the first duplexer 41 is located is connected, or when the first switch 43 is switched to the second output end 432 and the second switch 52 is switched to the second input end 522, the branch at which the second duplexer 42 is located is connected.

Based on the communication apparatus shown in FIG. 4, FIG. 6 is a schematic diagram of a structure of a communication apparatus according to Embodiment 3 of this application. As shown in FIG. 6, the communication apparatus may further include: a first antenna 61 and a second antenna 62. An output end of the first duplexer 41 is connected to the first antenna 61, and an output end of the second duplexer 42 is connected to the second antenna 62.

In the communication apparatus, the first duplexer 41 and the first antenna 61 are located in a same branch to implement sending and reception of one signal, and the second duplexer 42 and the second antenna 62 are located in a same branch to implement sending and reception of another signal.

An embodiment of this application provides a communication method using the communication apparatus according to any one of the foregoing apparatus embodiments, where the communication method may be performed by a terminal device including the foregoing communication apparatus. FIG. 7 is a flowchart of a communication method according to an embodiment of this application. As shown in FIG. 7, the communication method in this embodiment may include:

Step 701: Receive Carrier Configuration Information.

The carrier configuration information includes a bandwidth and/or a frequency of a carrier configured for a terminal device; and when the carrier configuration information corresponds to a first uplink band, a first switch in the communication apparatus is switched to a first output end; or when the carrier configuration information corresponds to a second uplink band, a first switch in the communication apparatus is switched to a second output end.

An access network device configures the carrier for the terminal device, and then sends the carrier configuration information to the terminal device by using a downlink signal. As described above, receive filters in two duplexers in the communication apparatus correspond to a first downlink band and a second downlink band respectively, and the first downlink band and the second downlink band may have the same bandwidth and different positions, or may have the same bandwidth and position, or both have a full bandwidth. A downlink band corresponding to the receive filter is greater than an uplink band corresponding to a transmit filter in the same duplexer. Therefore, when determining a state of the first switch, the terminal device focuses on configuration information of an uplink carrier in the carrier configuration information.

In a possible implementation, when the carrier configuration information received by the terminal device is the bandwidth of the carrier, the terminal device focuses on which of the two duplexers has a transmit filter that supports a band which the bandwidth of the uplink carrier belongs to. For example, the bandwidth of the uplink carrier is 703-733 MHz. In this case, the bandwidth of the uplink carrier corresponds to the first uplink band, and the terminal device switches the first switch in the communication apparatus to the first output end. The bandwidth of the uplink carrier is 718-748 MHz. In this case, the bandwidth of the uplink carrier corresponds to the second uplink band, and the terminal device switches the first switch in the communication apparatus to the second output end.

In a possible implementation, when the carrier configuration information received by the terminal device is the frequency of the carrier, the terminal device focuses on which of the two duplexers has a transmit filter that supports a band which the frequency of the uplink carrier belongs to. For example, the frequency of the uplink carrier is 718 MHz. In this case, the frequency of the uplink carrier corresponds to the first uplink band, and the terminal device switches the first switch in the communication apparatus to the first output end. The frequency of the uplink carrier is 733 MHz. In this case, the frequency of the uplink carrier corresponds to the second uplink band, and the terminal device switches the first switch in the communication apparatus to the second output end.

In a possible implementation, when the carrier configuration information received by the terminal device is the bandwidth and the frequency of the carrier, the terminal device focuses on which of the two duplexers has a transmit filter that supports a band which the bandwidth and the frequency of the uplink carrier belong to. Reference may be made to the foregoing description. Details are not described again herein.

Preferably, when the terminal device configures the bands of the transmit filter and the receive filter in the duplexer, an uplink carrier of the uplink band corresponding to the transmit filter and a downlink carrier of the downlink band corresponding to the receive filter need to follow a constraint relationship. That is, a bandwidth of the uplink carrier is within a bandwidth of a downlink mapped carrier, and the bandwidth of the downlink mapped carrier is obtained based on the first downlink band or the second downlink band and a default transceiving frequency interval.

FIG. 8 shows an example of a schematic diagram of a carrier configuration. As shown in FIG. 8, assuming that the terminal device switches the first switch in the communication apparatus to the first output end, in this case, a maximum bandwidth of the uplink carrier that can be supported by the terminal device is 703-733 MHz, and a maximum bandwidth of the downlink carrier is 758-803 MHz.

When the bandwidth of the configured downlink carrier is 763-803 MHz (40 MHz in total), the bandwidth of the downlink mapped carrier is 708-748 MHz. Because the bandwidth of the uplink carrier needs to be within the bandwidth of the downlink mapped carrier, the terminal device configures the bandwidth of the uplink carrier to be 708-733 MHz (25 MHz in total).

When the bandwidth of the configured downlink carrier is 758-798 MHz (40 MHz in total), the bandwidth of the downlink mapped carrier is 703-743 MHz. Because the bandwidth of the uplink carrier needs to be within the bandwidth of the downlink mapped carrier, the terminal device configures the bandwidth of the uplink carrier to be 703-733 MHz (30 MHz in total).

FIG. 9 shows an example of a schematic diagram of another carrier configuration. As shown in FIG. 9, assuming that the terminal device switches the first switch in the communication apparatus to the second output end, in this case, a maximum bandwidth of the uplink carrier that can be supported by the terminal device is718-748 MHz, and a maximum bandwidth of the downlink carrier is 758-803 MHz.

When the bandwidth of the configured downlink carrier is 763-803 MHz (40 MHz in total), the bandwidth of the downlink mapped carrier 708-748 MHz. Because the bandwidth of the uplink carrier needs to be within the bandwidth of the downlink mapped carrier, the terminal device configures the bandwidth of the uplink carrier to be 718-748 MHz (30 MHz in total).

When the bandwidth of the configured downlink carrier is 758-798 MHz (40 MHz in total), the bandwidth of the downlink mapped carrier 703-743 MHz. Because the bandwidth of the uplink carrier needs to be within the bandwidth of the downlink mapped carrier, the terminal device configures the bandwidth of the uplink carrier to be 718-743 MHz (25 MHz in total).

Step 702: Receive Scheduling Information.

The scheduling information indicates an uplink resource, and when the first switch in the communication apparatus is switched to the first output end, a bandwidth of the uplink resource is less than that of the first uplink band, or when the first switch in the communication apparatus is switched to the second output end, a bandwidth of the uplink resource is less than that of the second uplink band. A maximum bandwidth of the uplink resource allocated by the access network device to the terminal device cannot be greater than a bandwidth of an uplink band corresponding to a transmit filter of a duplexer when a branch at which the duplexer is located is connected. To be specific, when a branch at which a first duplexer is located is connected, the bandwidth of the uplink resource is less than that of the first uplink band, or when a branch at which a second duplexer is located is connected, the bandwidth of the uplink resource is less than that of the second uplink band.

The terminal device can ensure uplink and downlink transmission performance by using the following two methods.

I. Uplink Transmission Performance is Ensured Preferably.

A first downlink band and a second downlink band have a same bandwidth. That a first downlink band and a second downlink band have a same bandwidth may be understood as that the first downlink band and the second downlink band have a same bandwidth and position. For example, the first downlink band and the second downlink band are 758-803 MHz. The first downlink band includes a plurality of sub-bands, and each of the plurality of sub-bands corresponds to at least one sensitivity index. The bandwidth and/or the frequency of the carrier configured by the access network device for the terminal device corresponds to one of the plurality of sub-bands. In this case, the terminal device determines a sensitivity index of the communication apparatus based on the at least one sensitivity index corresponding to the sub-band. Preferably, the bandwidth of the configured downlink carrier may be divided into a plurality of sub-bands, each of the sub-bands defines at least one sensitivity index, and the terminal device relaxes to some extent sensitivity indexes of those of the plurality of sub-bands close to the uplink carrier.

II. Downlink Transmission Performance is Ensured Preferably.

(1) The terminal device may limit a quantity of resource blocks (resource block, RB) for sending uplink data. If the terminal device may use up to 50 RBs to send uplink data, due to the limitation on the quantity of RBs, even if the terminal device is allocated 50 RBs, the quantity of RBs still needs to be reduced when uplink data is actually sent, for example, only up to 45 RBs can be used to send uplink data. Preferably, only when the terminal device switches the first switch to the second output end, the terminal device needs to limit the quantity of RBs for sending uplink data. The quantity of RBs is an example description, and the quantity of RBs and the reduction of the quantity of RBs are not limited in this embodiment of this application.