This application provides a transmission method that improves performance of detecting a terminal device by a network device. The method includes may include determining, by a network device, frequency hopping sequences of N terminal devices grouped into a plurality of groups in each of L adjacent slots, where any two terminal devices in each group of terminal devices use a same frequency resource, any two groups of terminal devices in each slot use different frequency resources, and each group of terminal devices in each slot includes a maximum of K terminal devices, pilot signals used by each group of terminal devices are elements in a set that includes K different pilot signals, and pilot signals used by any two terminal devices in each group in each slot are different. The method may also include sending, by the network device, first indication information to a first terminal device in the N terminal devices, where the first indication information determines a frequency hopping sequence of the first terminal device and a pilot signal used by the first terminal device in each slot.