Over the past year wireless operators around the world have focused on the deployment of broad 5G coverage. As we are just now beginning to see true 5G devices enter the consumer market, these recent upgrades will support new spectrum options and greater spectral efficiency provided by the 5G standard. The near-term objective is simple: make sure network capacity keeps up with consumer demand.
As we look beyond near-term consumer demand, the 5G standard includes a series of Key Performance Indicators (KPIs) to address a series of use cases beyond today's wireless networks capability. Consider remote driving or e-health use cases where not only bandwidth but also ultra-high reliability communications are required. And possibly the use case supporting rapid forms of transit such as high speed trains travelling up to 300+ miles per hour. Finally, consider the use case of remote driving cars where one millisecond of latency is critical to avoid a disastrous accident.
Each of the use cases noted and many more can be summarized into three categories: Ultra-reliable and low-latency communications (URLLC), Enhanced mobile broadband (eMBB) and Massive machine type communications (mMTC). To achieve the full potential of one or more categories operators will need to acquire new spectrum and deploy fiber-based radio access network (RAN). Existing spectrum deployed today by operators can support 4G subscriber’s user experience; however, to address many of the 5G KPIs operators will need to look at new spectrum options such as higher frequency spectrum typically referred to as millimeter wave (mmWave). The mmWave part of the spectrum has large (measured in hundreds of Megahertz (MHz)) available spectral bands to achieve user experience capacity demands. However, mmWave spectrum is more impacted by environmental factors such as rain and snow. In order to overcome those challenges operators must densify their wireless network deploying small cell radios along roadways rather than traditional towers which today have an Inter Site Distance (ISD) in urban areas on the order of 1,500 feet. The next section will describe a series of architectures that provide the necessary capacity and performance requirements to meet the 5G KPIs. Each of the sections will provide an overview of the architecture, describe some of the salient features of the architecture and provide some guidance on when an architecture should be considered.