3GPP43.052GSM Cordless Telephony System (CTS), Phase 1Lower Layers of the CTS Radio Interface, Stage 2Release 16TS
A.1.1 Power measurement of BCCH carrier
CTS and GSM potentially share same frequency band. Thus signals emitted by a CTS-FP may impact the power measurement performed by the MS on GSM frequencies.
Signals emitted by a CTS-FP are:
· on the beacon frequency, maximum 6 bursts on 52 frames:
– the CTSBCH, permanently, 2 bursts every 52 frames;
– part of the CTSAGCH (non hopping), on demand, 4 bursts every 52 frames.
· on a defined set of frequencies, using Total Frequency Hopping procedure :
– the CTSPCH, on demand, 4 bursts every 52 frames;
– part of the CTSAGCH (hopping), on demand, 4 bursts every 52 frames;
– SACCH, FACCH, TCH/F, for each dedicated connection, total of 50 bursts every 52 frames.
The BCCH carrier power measured by the GSM-MS is according to GSM 05.08 and GSM 03.22 the average on 5 measurements, evenly spread in 5 s.
A.1.1.1 Power on CTS-FP beacon frequency seen by the GSM-MS in cell selection
Considering the logical channels mapping for a CTS-FP, the GSM-MS has a maximum probability of (6/416)n to see (n/5) bursts of the CTS-FP beacon in the 5 measurements, i.e. probability 0.014 to see 1/5 of the beacon power, 0.00020 to see 2/5 of the beacon power, …
A.1.1.2 Power on CTS-FP hopping frequencies seen by the GSM-MS in cell selection
On any other frequency, the CTS-FP has to perform Total Frequency Hopping. The power seen by the GSM-MS will depend on the number of frequencies used and the state of the FP (signalling, dedicated connection, …).
If there is one dedicated connection, one timeslot will be used, spread over the hopped frequencies. For example, when hopping on 8 frequencies, the impact on power is as low as for the beacon frequency.
A.1.2 Synchronisation of a GSM-MS
CTS and GSM share same burst format for frequency burst (FCH and CTSBCH-FB). Therefore a GSM-MS could perform misleading FCH detection. But the Synchronisation Bursts (SCH and CTSBCH-SB) have different training sequences. A GSM-MS will not be able to decode a CTSBCH-SB. In addition, multiframe scheme is different between BCCH and CTS beacon.