anchor.diff:  See <<rsl_dlcx_ind_msg>>
   
   
  +[[rsl-dynamic-channels]]
  +=== Dynamic Channel Combinations
  +
  +In the classic data model established by ETSI/3GPP for A-bis, each
  +timeslot (channel) is configured using a static channel combination by
  +means of A-bis OML.  Particularly in presence of GPRS services, this
  +is very unflexible and leads to inefficient use of air interface
  +resources.
  +
  +As such, several methods have been implemented to overcome this
  +limitation.  The fundamental operation can be outlined like this:
  +
  +* Configuration of a particular _dynamic_ channel combination via OML
  +* activation of TCH works like on a classic TCH channel combination
  +* activation of PDCH requires some specific PDCH activation procedure
  +
  +There are two variants implemented in the OsmoBTS A-bis dialect:
  +
   [[ipa_style_pdch_mgmt]]
  -=== IPA Style PDCH Management
  -
  -When using an IPA style dynamic TCH/F+PDCH channel type on an
  -on-air timeslot, there are a couple of non-standard RSL messages used
  -in order to activate or deactivate this timeslot in PDCH mode.
  +==== IPA Style Dynamic Channels
  +
  +This method is used when OML uses 'NM_CHANC_IPAC_TCHFull_PDCH' (0x80)
  +as channel combination for the given time-slot.
  +
  +'IPA style' refers to 'ip.access' compatible PDCH activation and deactivation.
  +
  +When the IPA style dynamic channel combination _TCH/F or PDCH_
  +is set, the non-standard 'PDCH ACTIVATE' (<<pdch_act>>) and 'PDCH
  +DEACTIVATE' (<<pdch_deact>>) procedures are used for switching an idle
  +channel into PDCH mode and back into idle mode.
   
   When the channel is used as TCH/F, regular circuit-switched activation
   is performed, like on any traditional TCH/F.   However, the BSC must
  
positive.code: See <<rsl_pdch_act>>, <<rsl_pdch_act_ack>>, <<rsl_pdch_act_nack>>
  
  [[pdch_deact]]
  ==== PDCH Deactivate
  
  This procedure is used by the BSC to request the BTS to deactivate an
  active PDCH on any an IPA style dynamic TCH/F+PDCH channel.
  
negative.code: related procedures are used to enable the PDCH.
  
  [[pdch_act]]
  ===== PDCH Activate
  
  This procedure is used by the BSC to request the BTS to activate an
  IPA style dynamic TCH/F+PDCH channel in PDCH mode.
  