d LTE-A The common names 4G LTE and LTE-A are overarching terms that cover a range of techniques, services, and features rather than any single technology. Not every feature will be deployed every- where, and that leads to variations in any real-world deployments and different requirements for each case. For example, small cells may be deployed to improve system throughput, increase cell density, and provide more user bandwidth at lower cost. Typically, they will only be deployed in appropriate loc- ations, such as densely trafficked urban downtown areas. Whatever the feature or technology being adopted, without providing the type of synchronization required to support it, the desired objectives will not be achieved. Table 10-11 summarizes the synchronization needs for several applications and use cases and indic- ates the impact of not meeting those requirements. Table 10-11 Synchronization Compliance for LTE Applications Application Need for Compliance Impact of Noncompliance Call initiation Call interference and dropped calls LTE-FDD Timeslot alignment Packet loss/collisions and spectral inefficiency LTE-A Proper time alignment of video signal de- Video broadcast interruption MBSFN coding from multiple BTS LTE-A Coordination of signals to/from multiple Poor signal quality at edge of cells, poor loca- MIMO/CoMP base stations tion-based service accuracy LTE-A eICIC Interference coordination Spectral inefficiency and service degradation For the basic LTE and LTE-A radio services, the frequency synchronization requirements remain the same as for the earlier generations of radio, namely 50 ppb at the air interface and 16 ppb at the BS or eNB interface. In addition to the frequency requirement, some other services have phase re- quirements because the operator applies specific technologies and techniques in the radio. Table 10-12 - summarizes the frequency and phase requirements for LTE. Table 10-12 Summary of Time Synchronization Requirements for LTE Radio Services Application Frequency Phase Accuracy Reference Acc