You can change time between repetition for chan_req according to ccch_conf, tx_integer. see 3GPP 4.08
but there’s a limitation which should be (if i’m not wrong) with cch_conf (non_combined) and tx_integer =32.
That way time between rach repetition is:
1 RACCH slot = 4,62 ms
Tx_Integer = T = 32 RACCH slots = 0,147 sec
S = 217 RACCH slots = 1,002 sec for non_combiend bcch+ tx_integer=32
Consequently time between repeated Chan_req if no IA is received is between:
1,002 sec (= S * 4,62) up to 1,144 sec (S + T – 1 = 248 * 4,62)
but it can still be too short.