5B.6 Beacon characteristics of physical channels

25.2213GPPPhysical channels and mapping of transport channels onto physical channels (TDD)Release 17TS

For the purpose of measurements, common physical channels that are allocated to particular locations (time slot, code) shall have particular physical characteristics, called beacon characteristics. Physical channels with beacon characteristics are called beacon channels. The locations of the beacon channels are called beacon locations. The ensemble of beacon channels shall provide the beacon function, i.e. a reference power level at the beacon locations, regularly existing in each radio frame. Thus, beacon channels must be present in each radio frame, the only exception is when idle periods are used to support time difference measurements for location services [9]. Then it may be possible that the beacon channels occur in the same frame and time slot as the idle periods. In this case, the beacon channels will not be transmitted in that particular frame and time slot.

5B.6.1 Location of beacon channels

The beacon locations are determined by the SCH and depend on the SCH allocation case, see subclause 5B.4.4:

Case 1) The beacon function shall be provided by the physical channels that are allocated to channelisation code and to TS#k, k=0,…,14.

Case 2) The beacon function shall be provided by the physical channels that are allocated to channelisation code and to TS#k and TS#k+8, k=0,…,6.

Note that by this definition the P-CCPCH always has beacon characteristics.

5B.6.2 Physical characteristics of beacon channels

The beacon channels shall have the following physical characteristics. They:

– are transmitted with reference power;

– are transmitted without beamforming;

– use burst type 1 or burst type 4 when MBSFN is applied to beacon channels;

– use midamble m⁽¹⁾ and m⁽²⁾ exclusively in this time slot; and

– midambles m⁽⁹⁾ and m⁽¹⁰⁾ are always left unused in this time slot, if 16 midambles are allowed in that cell.

Note that in the time slot where the P-CCPCH is transmitted only the midambles m⁽¹⁾ to m⁽⁸⁾ shall be used, see 5B.7.1. Thus, midambles m⁽⁹⁾ and m⁽¹⁰⁾ are always left unused in this time slot.

Note that when MBSFN is applied to beacon channels there is a single midamble and hence midamble m⁽¹⁾ is exclusively used in the timeslot.

The reference power corresponds to the sum of the power allocated to both midambles m⁽¹⁾ and m⁽²⁾. Two possibilities exist:

– If SCTD antenna diversity is not applied to beacon channels all the reference power of any beacon channel is allocated to m⁽¹⁾.

– If SCTD antenna diversity is applied to beacon channels, for any beacon channel midambles m⁽¹⁾ and m⁽²⁾ are each allocated half of the reference power.