ch compliance is noted allows for different teams (and customers) to quickly familiarize themselves with the compliance matrix (Fig. 10-3). Unit testing can be implemented at this feature-by-feature level in a system test setup- even when some features are more easily tested in a unit test environment. These tests are mainly targeting CU and DU systems which is where the bulk of 3GPP defined features are hosted. In addition, system-level tests can be targeted to the traceability matrix to ensure that the complete system has been tested. Note that this system-level testing can be highly complex and require in-depth knowledge of 3GPP standards and complex (third-party test) environments. Assuming abovementioned example for PDCP-level feature testing, including pointed sce- narios for the following examples (and more!): ciphering and integrity using AES32, SNOW3G, and ZUC algorithm for user plane and control plane data header compression and decompression for user plane data using different Robust Header Compression profiles 3GPP NSA and SA deployment options in-sequence delivery of upper layer PDUs at reestablishment of lower layers duplicate elimination of lower layer service data unit (SDUs) at reestablishment of lower layers for radio bearers mapped on RLC AM PDCP-related functions for below NSA function secondary node addition secondary node change secondary node modification reconfiguration with sync and key change reconfiguration with sync but without key change 334 Open Radio Access Network (O-RAN) Systems Architecture and Design PSCell change during inter- and intra-DU bearer-type change from spilt to Sequence Number (SN) terminated Master Cell Group (MCG) bearer bearer-type change from SN terminated MCG bearer to split bearer UL and DL COUNT Thresh hold PDCP discard timer DL and UL data rate limiting for ENDC spilt bearers using flow control algorithms TS36.323 Technical Specification Group Radio Access Network Evolved Universal Terrestrial Radio Access (E-UTRA) Packet Data Convergence Protocol (PDCP) spec