Internet Standards/CD2.mdf/ccitt/1992/q/q1063.asc

Text File | 1991-12-30 | 10KB | 246 lines

Recommendation Q.1063




              DIGITAL PLMN CHANNEL STRUCTURES AND ACCESS CAPABILITIES
                    AT THE RADIO INTERFACE (Um REFERENCE POINT)




1     General


      This Recommendation defines a limited set of channel types, access capabilities and channel
configurations with respect to the Um reference point (i.e. the radio interface,  see
Recommendation Q.1062).


2     Definitions


      A channel represents a specific portion of the information carrying capability of an interface.

2.1   Channels are classified by types according to common characteristics. Channel types appearing
at the radio interface are identified in sections 3 and 4.

2.2   The complete interface between a Base Station (BS) and its associated Mobile Stations (MS) is
defined by the interface structure at a given  point  in  time.  This  interface  may
change over time.

2.3   An MS channel configuration is defined by the interface structure that the MS actually uses to
transmit or receive information with respect to the BS at a given point in time. This
interface structure may change over time.

2.4   An access capability defines possible access arrangements with respect to the number and type
of channels that can be  supported  by  an  equipment.  In  this  way  an  MS  access
capability is the set of possible channel configurations supported by the equipment. Similarly,
the BS access capability may be considered to be a super-set with respect to the MS.

      The access capability is thus a fixed attribute of an equipment.


3     Functional channel types


      In this Recommendation the functional channel types are defined relative to the radio interface. This channels are used to carry information streams defined at the Sm reference
point, and which are to be specified in a separate Recommendation.

3.1   wTraffic channelw

      The Traffic Channel (TCH) is intended to carry a wide variety of user information streams. A
distinguishing  characteristic  is  that  this  channel  does  not  carry  signalling
information for call control, MS management or RF transmission management. This signalling
information is carried by other types of channels, e.g. control channels.

3.2   wControl channelw

      The Control Channel (CCH) consists of the Associated Control Channel (ACCH), Dedicated Control
Channel (DCCH), Common Control Channel (CCCH), Broadcast Control Channel  (BCCH)  and
User Packet Channel (UPCH). These channels  carry  signalling  information  for  call
control, MS management, RF transmission management, and other functions.





4     Channel usage for user information


4.1   wTCHw

      Traffic channels are physical gross rate channels, accompanied with timing.

      Traffic channels are intended to carry a wide variety of user information streams.

      The provision of these information streams is to be defined in a separate Recommendation.

      TCHSs may be used to provide access to a variety of communications modes within the PLMN and
the networks it provides access to. Examples of these are:

      i)  circuit switched communications; and

      ii)  packet switched communications, supporting packet mode terminals.

      In case i), the PLMN can provide either a transparent connection, or a connection specifically
suited to a particular service, such as telephony.

      In case ii), the traffic channel carries protocols at layers 2 and 3 according to Recommendation X.25, or other packet-mode standardized protocols.


5     Channel usage for control


5.1   Control channels are used to provide active Mobile Stations and Base Stations a means of
signalling communication across the radio interface.

5.2   A Mobile Station channel configuration contains one or more control channels. These control
channels change depending on the  required  channel  configuration.  RF  transmission
management signalling functions ensure the continuity of communication when a change in
the control channel type occurs.

      Control channels are classified by control channel types, which have common characteristics.

      Control channels are primarily intended to carry signalling information for call control,
mobility management and RF transmission management.

5.3   In addition to signalling information, control channels may also carry user packet data (e.g.
for Short Message Service).

5.4   wControl channelsw

5.4.1     wBroadcast control channelw

      The BCCH provides the broadcast capability for a variety of information streams from Base
Stations to Mobile Stations, including information necessary for the MS  to  register
in the system (e.g. synchronization data or CCCH coordinates).

      The notion of a BCCH is defined for applications where the CCCH is insufficient in capacity in
light of signalling traffic, or where only unidirectional communication to an  MS  is
required.

5.4.2     wCommon control channelw

      A CCCH is a point-to-multipoint, bidirectional control channel. A CCCH is primarily intended to
support  signalling  information  for  call  control,  mobility  management  and   RF
transmission management.

      A CCCH uses a layered protocol to be defined in a separate Recommendation. In particular the
CCCH is a common resource available to more than one MS within a specific  geographic
area. In this way the CCCH is managed and allocated based on specific  random  access
techniques.

5.4.3     wUser packet channelw

      A UPCH is a point-to-multipoint, bidirectional control channel. A UPCH is primarily intended to
support user packet data.

      A UPCH uses a layered protocol to be defined in a separate Recommendation. In particular, the
UPCH is a common resource available to more than one MS within a specific  geographic
area. In this way the UPCH is managed and allocated based on specific  random  access
techniques.

5.4.4     wAssociated control channelw

      An ACCH is a point-to-point, bidirectional control channel that supports both signalling and
user packet data. The ACCH is always associated with the TCH, and provides  for  call
control mobility management and RF transmission management signalling. The ACCH uses a
layered protocol to be defined in a separate Recommendation.

5.4.5     wDedicated control channelw

      A DCCH is a point-to-point, bidirectional control channel that supports both signalling and
user packet data. The DCCH is not associated with an TCH. The  DCCH  uses  a  layered
protocol to be defined in a separate Recommendation.

5.4.6     wSets of functional channelsw

5.4.6.1   wCommon access channelsw

      The functional channels defined in  5.4.1, 5.4.2 and 5.4.3 are classified as Common Access
Channels (CAC).

5.4.6.2   wUser specific channelsw

      The functional channels described in  5.4.4  and 5.4.5 are classified as user specific
channels.

6     Base station access capability

      The base station access capability provides the means to describe the actual BS access
arrangement (i.e. the type and functional groups of channels supported by the BS).

6.1   The BS access capability is a combination of functional channels defined in  5.4. Each group
operates independently.

6.2   For example a BS access capability may consist of the following combination:

      One BCCH; n1 (CCCH), n2 (UPCH), n3 (DCCH) and n4 (TCH + ACCH).

      Specific access capabilities are an area for further study.

7     Mobile station access capability

      The mobile station access capability provides the means to describe the actual MS access
arrangement (i.e. the type and functional groups of channels supported by the MS).

7.1   The MS access capability is defined by a combination of functional channels defined in  5.4.

7.2   The access capability defined for a mobile station at a minimum consists of a BCCH and/or a
CCCH. In addition a MS access capability may include a UPCH and/or a  DCCH  and/or  a

TCH + ACCH.




8     Channel configurations

8.1   At any point in time an MS accesses a unique physical set of channels that are available on its
radio interface. Examples of the channel  configuration  are  identified  below.  The
actual combination is dependent on the physical BS configuration.

8.2   Possible channel configurations accessible by an MS at any one point in time are as follows:

      i)       BCCH

      ii)      CCCH

      iii)     UPCH

      iv)      DCCH

      v)       TCH + ACCH

      Configuration i) is defined for the state in which a unique physical channel is not allocated
to an MS and a unidirectional communication is provided (i.e., upon power-on or after
extended interruption of the physical connection due to poor propagation conditions).

      Configuration ii) is defined for the state in which a unique physical channel is not allocated
to an MS, the MS is not idle and a bidirectional communication is required.

      Configuration iii) is defined for the state in which a unique physical channel is not allocated
to an MS but the MS may support user packet data on the common physical channels.

      Configuration iv) is defined for the state in which a unique physical channel is allocated to
an MS and a dedicated control channel is provided.

      Configuration v) is defined for the state in which a unique physical channel is allocated to an
MS and a traffic channel and an associated control channel are provided.




                                  FIGURE 1/Q.1063

                                   Channel types