A communication method performed by a first communications device, the method comprising: • sending a first preamble to a second communications device, wherein the first preamble occupies a first time domain resource and a first frequency domain resource, and a first time unit corresponding to the first time domain resource is a time unit, which has an index number i in a system frame; • determining a scramble value of a first random access response, RAR, being a RAR corresponding to the first preamble, according to: RA − RNTI = 1 + i + S reference × N scs / N reference × ƒ _ id + F max × S reference SFN _ i d mod W max / N frame where RA - RNTI is the scramble value of the first RAR, i represents the index number of the first time unit corresponding to the first time domain resource of a current numerology, S reference represents a quantity of time units included in a system frame of a reference S numerology, N reference represents a subcarrier spacing value of the reference numerology, N scs represents a subcarrier spacing value of the current numerology, N frame represents a quantity of time units in a system frame of the current numerology, f _ id represents an index number of a candidate frequency domain resource corresponding to the first frequency domain resource, F max is a maximum quantity of candidate frequency domain resources that are in one of the time units and that are of the first preamble, SFN_id represents an index number of a first system frame in which the first time domain resource is located, and W max represents a maximum RAR time window length; • receiving, in a time window of the first RAR according to the scramble value of the first RAR, the first RAR from the second communications device, wherein a length of the time window of the first RAR is less than or equal to M time units, wherein a value of M is an integer multiple of 80. • sending a first preamble to a second communications device, wherein the first preamble occupies a first time domain resource and a first frequency domain resource, and a first time unit corresponding to the first time domain resource is a time unit, which has an index number i in a system frame; • determining a scramble value of a first random access response, RAR, being a RAR corresponding to the first preamble, according to: RA − RNTI = 1 + i + S reference × N scs / N reference × ƒ _ id + F max × S reference SFN _ i d mod W max / N frame where RA - RNTI is the scramble value of the first RAR, i represents the index number of the first time unit corresponding to the first time domain resource of a current numerology, S reference represents a quantity of time units included in a system frame of a reference S numerology, N reference represents a subcarrier spacing value of the reference numerology, N scs represents a subcarrier spacing value of the current numerology, N frame represents a quantity of time units in a system frame of the current numerology, f _ id represents an index number of a candidate frequency domain resource corresponding to the first frequency domain resource, F max is a maximum quantity of candidate frequency domain resources that are in one of the time units and that are of the first preamble, SFN_id represents an index number of a first system frame in which the first time domain resource is located, and W max represents a maximum RAR time window length; • receiving, in a time window of the first RAR according to the scramble value of the first RAR, the first RAR from the second communications device, wherein a length of the time window of the first RAR is less than or equal to M time units, wherein a value of M is an integer multiple of 80.