Handover Access

you can have a look to 3gpp.org.

i can have a look later, but i’m afraid i’m going to forget 🙂

I found the “Handover Access” format finally. it contains 1 octet usefull data like “Rach” message. both of them will be sent on “Access Burst” so sometimes BTS detects “Handover Access” Burst as “Rach” wrongly and BSC assigns SDCCH to this request (SDCCH GHOST) that waste the SDCCH resource.

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.

Hi,
what’s the cause of Handover failure-unspecified? Radio? MSC?
BR,
Dell

hi,

HO ACCESS is rarely sent on SACCH. If cell is synchronized (intra-BTS HO), then HO ACCESS is sent on FACCH exclusively, 4 times.

In case on non-sycn cells :

3GPP 44.018

3.4.4.2.2 Non synchronized cell case

After having switched to the assigned channels, the mobile station starts repeating the HANDOVER ACCESS message in successive layer 1 frames on the main DCCH ( = FACCH) and optionally on the SACCH. This message is sent in an access burst. Its content is reduced to the handover reference information element. The mobile station starts timer T3124 at the start point of the timeslot in which the HANDOVER ACCESS message is sent the first time on the main DCCH.