Communication method and apparatus

1 . A method applied to a terminal device, the method comprising:

obtaining first information and second information, wherein the first information is used to determine a length of a first-type symbol component, the second information is used to determine at least one of a length of a second-type symbol component and a length of a third-type symbol component, and the length of the first-type symbol component is greater than the length of the third-type symbol component;

determining a plurality of signal blocks based on the first information and the second information, wherein each signal block of the plurality of signal blocks comprises a plurality of modulation symbols, wherein

a first signal block of the plurality of signal blocks comprises the first-type symbol component and the second-type symbol component, a second signal block of the plurality of signal blocks comprises modulation symbols that are the same as modulation symbols in the first-type symbol component and the second-type symbol component in the first signal block, a (k+1) th signal block comprises modulation symbols that are the same as modulation symbols in a second-type symbol component and the third-type symbol component in a k th signal block, k≥2, and k is an integer;

processing each of the plurality of signal blocks to obtain an orthogonal frequency division multiplexing (OFDM) symbol corresponding to the signal block; and

sending the OFDM symbol.

2 . The method according to claim 1 , wherein:

the first-type symbol component is first X modulation symbols in the first signal block, and the second signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the first-type symbol component in the first signal block and a last modulation symbol of the second signal block, wherein a value of m is determined based on a duration of a cyclic prefix, m>1, and X>1;

a second-type symbol component in a (k−1) th signal block is last Y modulation symbols in the (k−1) th signal block, and the k th signal block comprises m modulation symbols between an end modulation symbol of modulation symbols that are the same as the modulation symbols in the second-type symbol component in the (k−1) th signal block and a last modulation symbol of the k th signal block, wherein Y≥1; and

the third-type symbol component in the k th signal block is first Z modulation symbols in the k th signal block, Z<X, Z≥1, and the (k+1) th signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the third-type symbol component in the k th signal block and a last modulation symbol of the (k+1) th signal block.

3 . The method according to claim 2 , wherein:

the length of the third-type symbol component is a first preset value; and

the second information indicates a sum of the length of the second-type symbol component and a length of the cyclic prefix.

4 . The method according to claim 1 , wherein the first information indicates a difference between the length of the first-type symbol component and the length of the third-type symbol component.

5 . The method according to claim 1 , wherein determining the plurality of signal blocks based on the first information and the second information comprises:

determining a size of a transport block based on the first information and the second information; and

determining, based on the size of the transport block, a plurality of signal blocks corresponding to third information, wherein the third information is information that needs to be sent by the terminal device to a network device.

6 . The method according to claim 5 , wherein determining the size of the transport block based on the first information and the second information comprises:

determining, based on the length of the first-type symbol component, a quantity of modulation symbols comprised in the first-type symbol component;

determining, based on the length of the second-type symbol component, a quantity of modulation symbols comprised in the second-type symbol component; determining, based on the length of the third-type symbol component, a quantity of modulation symbols comprised in the third-type symbol component;

determining a first resource element quantity based on the quantity of modulation symbols comprised in the first-type symbol component, the quantity of modulation symbols comprised in the second-type symbol component, and the quantity of modulation symbols comprised in the third-type symbol component, wherein the first resource element quantity indicates a quantity of resource elements corresponding to a same modulation symbol between different signal blocks in one slot; and

determining the size of the transport block based on a second resource element quantity and the first resource element quantity, wherein the second resource element quantity is a quantity of resource elements used to transmit the third information in one slot.

7 . The method according to claim 6 , wherein determining the size of the transport block based on the second resource element quantity and the first resource element quantity comprises:

determining the size of the transport block based on a difference between the second resource element quantity and the first resource element quantity; or

determining the size of the transport block based on a difference between the second resource element quantity and a first quantized value, wherein the first quantized value is obtained after the first resource element quantity is quantized at a preset spacing.

8 . A method applied to a network device, the method comprising:

sending first information and second information to a terminal device, wherein the first information is used to determine a length of a first-type symbol component, the second information is used to determine at least one of a length of a second-type symbol component and a length of a third-type symbol component, and the length of the first-type symbol component is greater than the length of the third-type symbol component;

receiving a plurality of orthogonal frequency division multiplexing (OFDM) symbols from the terminal device, wherein the plurality of OFDM symbols are in a one-to-one correspondence with a plurality of signal blocks, each signal block comprises a plurality of modulation symbols, a first signal block comprises the first-type symbol component and the second-type symbol component, a second signal block comprises modulation symbols that are the same as modulation symbols in the first-type symbol component and the second-type symbol component in the first signal block, a (k+1) th signal block comprises modulation symbols that are the same as modulation symbols in a second-type symbol component and the third-type symbol component in a k th signal block, k≥2, and k is an integer;

determining a receive window corresponding to each of the plurality of OFDM symbols; and

obtaining a demodulation signal of each OFDM symbol based on the receive window corresponding to each OFDM symbol.

9 . The method according to claim 8 , wherein:

the first-type symbol component is first X modulation symbols in the first signal block, and the second signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the first-type symbol component in the first signal block and a last modulation symbol of the second signal block, wherein a value of m is determined based on a duration of a cyclic prefix, m>1, and X>1;

a second-type symbol component in a (k−1) th signal block is last Y modulation symbols in the (k−1) th signal block, and the k th signal block comprises m modulation symbols between an end modulation symbol of modulation symbols that are the same as the modulation symbols in the second-type symbol component in the (k−1) th signal block and a last modulation symbol of the k th signal block, wherein Y≥1; and

the third-type symbol component in the k th signal block is first Z modulation symbols in the k th signal block, Z<X, Z≥1, and the (k+1) th signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the third-type symbol component in the k th signal block and a last modulation symbol of the (k+1) th signal block.

10 . The method according to claim 9 , wherein determining the receive window corresponding to each of the plurality of OFDM symbols comprises:

determining, based on the length of the first-type symbol component, a receive window corresponding to a first OFDM symbol in the plurality of OFDM symbols, wherein a start point of the receive window corresponding to the first OFDM symbol is associated with the length of the first-type symbol component; and

determining, based on the duration of the cyclic prefix, a receive window corresponding to a k th OFDM symbol, wherein

a spacing between an end point of the receive window corresponding to the first OFDM symbol and a start point of a receive window corresponding to a second OFDM symbol is T 1 sampling points, a spacing between an end point of the receive window corresponding to the k th OFDM symbol and a start point of a receive window corresponding to a (k+1) th OFDM symbol is T 2 sampling points, T 1 <T 2 , and T 1 and T 2 are positive integers.

11 . The method according to claim 10 , wherein determining, based on the length of the first-type symbol component, the receive window corresponding to the first OFDM symbol in the plurality of OFDM symbols comprises:

determining at least one candidate receive window based on the length of the first-type symbol component; and

determining, based on a preset parameter, the receive window corresponding to the first OFDM symbol from the at least one candidate receive window, wherein

a spacing between any two adjacent start points in start points of the at least one candidate receive window is ΔT sampling points, and ΔT is a preset value and is a positive integer.

12 . The method according to claim 8 , further comprising:

determining, based on the demodulation signal of each OFDM symbol, a received signal of a signal block corresponding to each OFDM symbol;

demapping, based on the first information and the second information, the received signal of the signal block corresponding to the OFDM symbol; and

obtaining received bit information based on a demapping result.

13 . The method according to claim 8 , further comprising:

determining a size of a transport block based on the first information and the second information; and

decoding received bit information based on the size of the transport block to obtain third information, wherein the third information is information that needs to be sent by the terminal device to the network device.

14 . An apparatus for a terminal device or a chip in a terminal device, the apparatus comprising a processor and a memory with instructions stored thereon, wherein the instructions, when executed by the processor, enable the apparatus to:

obtain first information and second information, wherein the first information is used to determine a length of a first-type symbol component, the second information is used to determine at least one of a length of a second-type symbol component and a length of a third-type symbol component, and the length of the first-type symbol component is greater than the length of the third-type symbol component;

determine a plurality of signal blocks based on the first information and the second information, wherein each signal block of the plurality of signal blocks comprises a plurality of modulation symbols, a first signal block comprises the first-type symbol component and the second-type symbol component, a second signal block comprises modulation symbols that are the same as modulation symbols in the first-type symbol component and the second-type symbol component in the first signal block, a (k+1) th signal block comprises modulation symbols that are the same as modulation symbols in a second-type symbol component and the third-type symbol component in a k th signal block, k≥2, and k is an integer;

process each of the plurality of signal blocks to obtain an orthogonal frequency division multiplexing (OFDM) symbol corresponding to the signal block; and

send the OFDM symbol.

15 . The apparatus according to claim 14 , wherein:

the first-type symbol component is first X modulation symbols in the first signal block, and the second signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the first-type symbol component in the first signal block and a last modulation symbol of the second signal block, wherein a value of m is determined based on a duration of a cyclic prefix, m>1, and X>1;

a second-type symbol component in a (k−1) th signal block is last Y modulation symbols in the (k−1) th signal block, and the k th signal block comprises m modulation symbols between an end modulation symbol of modulation symbols that are the same as the modulation symbols in the second-type symbol component in the (k−1) th signal block and a last modulation symbol of the k th signal block, wherein Y≥1; and

the third-type symbol component in the k th signal block is first Z modulation symbols in the k th signal block, Z<X, Z≥1, and the (k+1) th signal block comprises m−1 modulation symbols between a start modulation symbol of modulation symbols that are the same as the modulation symbols in the third-type symbol component in the k th signal block and a last modulation symbol of the (k+1) th signal block.

16 . The apparatus according to claim 15 , wherein:

the length of the third-type symbol component is a first preset value; and

the second information indicates a sum of the length of the second-type symbol component and a length of the cyclic prefix.

17 . The apparatus according to claim 14 , wherein the first information indicates a difference between the length of the first-type symbol component and the length of the third-type symbol component.

18 . The apparatus according to claim 14 , wherein the instructions, when executed by the processor, further enable the apparatus to, while determining the plurality of signal blocks based on the first information and the second information:

determine a size of a transport block based on the first information and the second information; and

determine, based on the size of the transport block, a plurality of signal blocks corresponding to third information, wherein the third information is information that needs to be sent by the terminal device to a network device.

19 . The apparatus according to claim 18 , wherein the instructions, when executed by the processor, further enable the apparatus to:

while determining the size of the transport block based on the first information and the second information:

determine, based on the length of the first-type symbol component, a quantity of modulation symbols comprised in the first-type symbol component,

determine, based on the length of the second-type symbol component, a quantity of modulation symbols comprised in the second-type symbol component, and

determine, based on the length of the third-type symbol component, a quantity of modulation symbols comprised in the third-type symbol component;

determine a first resource element quantity based on the quantity of modulation symbols comprised in the first-type symbol component, the quantity of modulation symbols comprised in the second-type symbol component, and the quantity of modulation symbols comprised in the third-type symbol component, wherein the first resource element quantity indicates a quantity of resource elements corresponding to a same modulation symbol between different signal blocks in one slot; and

determine the size of the transport block based on a second resource element quantity and the first resource element quantity, wherein the second resource element quantity is a quantity of resource elements used to transmit the third information in one slot.

20 . The apparatus according to claim 19 , wherein the instructions, when executed by the processor, further enable the apparatus to, while determining the size of the transport block based on the second resource element quantity and the first resource element quantity: determine the size of the transport block based on a difference between the second resource element quantity and the first resource element quantity; or determine the size of the transport block based on a difference between the second resource element quantity and a first quantized value, wherein the first quantized value is obtained after the first resource element quantity is quantized at a preset spacing.