ed Reliability 6.6.4.4 Frequency and Time Synchronization 6.6.4.5 Energy Efficiency 6.6.5 Higher Layers 6.6.5.1 xHaul Network Topology 6.6.5.2 Transport Protocols 6.6.5.3 Protocol Stacks for User Traffic 6.6.5.4 Technology Comparison 6.6.6 Conclusions References NG-RAN Deployment Considerations 379 Andreas Neubacher and Vishwanath Ramamurthi Introduction Key Ideas Deployment Objectives and Challenges 7.3.1 Where to Provide Coverage 7.3.2 Network Capacity and Compute Resource Planning 7.3.2.1 Air Interface Capacity 7.3.2.2 Compute Resources for Edge Computing Services 7.3.2.3 Reliability Considerations 7.3.3 Service Fulfillment Criteria Deployment Considerations 7.4.1 Deployment Cost 7.4.2 Spectrum and Radio Propagation Considerations 7.4.3 5G Frequency Ranges 7.4.4 Transport Considerations 7.4.5 Baseband Pooling 7.4.6 Choice of a NG-RAN Split Architecture 7.4.6.1 Sub-6 GHz Case 394 7.4.6.2 High-Band (mmWave) Case Conclusions 395 References 395 Index 397 Preface This is a different kind of book about 5G. Most books on this subject (5G in particular, or wireless technologies in general) focus on the physical layer. While the physical layer (together with the access stratum protocol stack) is extremely important and is arguably the key aspect of any wireless technology responsible for most of its performance characteristics, curiously enough it is not necessarily the most important factor when determining how successful a certain wireless technology would be in the market. The second largest category of books on wireless technologies typically focus on the core network, as it is often the core network features and design that determine the kind of ser- vices that a given technology would provide to operators and users. Without questioning the importance of the core network, we note that when it comes to the deployment of a new wireless technology by an operator, the core network is perhaps the most critical com- ponent as failures in the core may (and often do) affect the whole network and all the users. Nevertheles