This is an implementation of Packet Control Unit (PCU) according to TS 04.60

The PCU is part of BSS, so it connects directly to SGSN.

The performance tests are performed with following commit versions of osmo
components

libosmocore:    q136e73764e7f58e52ffb13d01304fef30eb7d291
osmo-bts:         99642656a067c2e16a1b2f1e5eb34529564c584d
libosmo-abis:    c1cf14cae8a4ff8d60976eb188344595755448d5
openbsc :         5b692d0a5c1c388916c21e623edde28505ec1b02

== Current limitations ==

 * No PFC support
 * No fixed allocation support
 * No extended dynamic allocation support
 * No unacknowledged mode operation
 * No PCCCH/PBCCH support
 * Only single slot assignment on uplink direction
 * No half-duplex class support (only semi-duplex)
 * No handover support
 * No measurement support
 * No TA loop
 * No power loop
 * No CS loop