I shall share what I found on HANDOVER ACCESS. HO Access Burst is basically a burst of bits – the 41 sync bits. There is a long guard period followed by 8 tail bits. This is followed by 26 encrypted data bits followed by 4 tail bits. Bits 88 – 156 are long guard bit period – to avoid any collision with other such access bursts.
The access burst is sent in 4 consecutive time slots if the systems are TDMA synchronized. Else the MS keeps on sending this burst unless the BSS replies with a PHYSICAL INFORMATION message containing the TIMING ADV information or Timer T3124 expires (HANDOVER FAILED).
Reference – Gsm – Architecture, Protocols and Services – Jörg Eberspächer, Hans-Joerg Vögel, Christian Bettstetter, Christian Hartmann | Page 152
Sorry to dig out this thread after so long. However the info may be useful to somebody else.