Abstract: The present disclosure relates to Hybrid Automatic Repeat Request (HARQ) in wireless communication technologies, particularly HARQ for IEEE 802.11, i.e. HARQ for Wi-Fi. One example transmitting device is configured to encapsulate a data unit in a container unit, and encode the container unit into a codeword set of one or more codewords. One example receiving device is configured to receive, from a transmitting device, at least one codeword set of one or more codewords, decode the codewords of the codeword set to obtain a container unit, and decapsulate the container unit to obtain a data unit. A bit-size of the container unit is equal to a bit-size of the codeword set in the transmitting device and the receiving device.

Abstract: This application provides a communication method and apparatus, and relates to the communication field. The method includes: generating a physical layer protocol data unit PPDU, where the PPDU includes a first field indicating that the PPDU is an extremely high throughput sounding null data packet EHT sounding NDP transmitted based on orthogonal frequency division multiple access OFDMA, the PPDU further includes an extremely high throughput-long training field EHT-LTF and a packet extension PE field, and the PE field is adjacent to the EHT-LTF; and sending the PPDU. In this way, a Bfee may determine, based on the first field in the PPDU, that the PPDU is the EHT sounding NDP transmitted based on OFDMA, perform channel estimation by using the PPDU, and feed back channel state information to a Bfer, to implement functions such as beamforming and resource scheduling for OFDMA transmission, thereby improving channel quality and a throughput.

Abstract: A radio physical layer protocol data unit (PPDU) sending method includes: obtaining, a radio physical layer protocol data unit (PPDU), wherein the PPDU includes a high efficiency-signal field A (HE-SIG-A) and a high efficiency-signal field B (HE-SIG-B), the HE-SIG-A includes a field indicating a quantity of orthogonal frequency division multiplexing (OFDM) symbols in the HE-SIG-B, and wherein a value of the field indicates one of the following: that the quantity of OFDM symbols included in the HE-SIG-B is greater than or equal to 16, or the quantity of OFDM symbols included in the HE-SIG-B; and sending the PPDU.

Abstract: The present invention relates to a method for the manufacture of an improved ureaform fertilizer. The method consists in the condensation of urea and formaldehyde carried out in a controlled system having a pH between 3.5 and 4.2 wherein the overall concentration of the reagents is in the range of 20 to 40% by weight. The ratio between the reagents is between 1.2 to 1.5 moles of urea to 1 mole of formaldehyde and the temperature of the reaction is kept between 15.degree. C. to 40.degree. C. Examples of preferred controlled systems are H.sub.3 PO.sub.4 -KH.sub.2 PO.sub.4 and H.sub.3 PO.sub.4 -NH.sub.4 H.sub.2 PO.sub.4. The method can also be performed in a continuous manner giving rise to an overall quantitative yield, and being temperature self-regulating.The ureaform obtained by the method has an activity index of over 75 and excellent physical properties.