signal quality measurements in osmo-trx

Hi.

I'm working on http://projects.osmocom.org/issues/1616 and wonder about $subj.

In case of sysmobts, osmo-pcu obtain this data directly from DSP: * RSSI (dBm) * burst timing (in quarter of bits) * link quality (in dB) * BER

The first and last value seems to be easy from what I see in src/osmo-bts-trx/scheduler_trx.c What about burst timing (necessary to compute TA in the absence of PTCCH) and link quality (measure of C / I where C is carrier and I is interference power) - how can I compute those or some estimator to those values?