OPTIMIZING SYNC SWITCHING FOR 5G Perhaps one of the most criminally understated 5G deployment hurdles is optimizing sync switching. This results from the transition of Frequency Division Duplexing (FDD) spectral usage techniques, prevalent with LTE bands, to Time Division Duplexing (TDD), found in most primary 5G bands like C-band and 2.5 GHz. The consequences of poorly optimized sync switching can be enormous, causing reduced throughput (or none at all), interference with other bands, and even negatively affecting other mobile carriers sharing the same DAS.
TDD is an incredible boost for spectral efficiency, but the downside is the equipment requires a precise, synch- ronized switch between the network and user equipment to change between UL and DL. This synchronization is critical to avoid interference and ensure optimal performance. The consequences of poorly optimized sync switching can be enormous, causing reduced throughput (or none at all), interference with other bands, and even negatively affecting other mobile carriers sharing the same DAS. TDD is an ideal spectral usage technique and imp- ortant for the success of 5G because spectral efficiency is key to allowing more bandwidth for over-the-air backhaul instead of costly cable between the cell site and the indoor network.
bands in mind. As a result, the components used in prior systems may not be rated for the required frequencies. In some cases, these can be material or physical size issues. For example, the materials used in passive components have intrinsic electrical characteristics, such as dielectric constant and magnetic permeability, which affect their performance at different frequencies. Certain dielectric materials may have higher loss at high fre- quencies, leading to increased signal attenuation. The physical size and structure of passive components can also determine the range of frequencies they can effectively handle. Components designed for lower frequencies typically have larger dimensions, and as the frequency increases, these components may not be able to accommodate the corresponding wavelength, leading to poor performance or non-operation. This could necessitate a comprehensive overhaul of passive components in an existing network to ensure compatibility and performance. Before upgrading to 5G, integrators must verify that the passive components can meet the latest technology standards, as manufacturers continually update components to accommodate higher frequencies. Otherwise, they will need to be replaced during the network refresh.
It isn’t just a matter of adapting to new technologies, but also to people's behaviors. In the thick of the 4G/LTE wireless generation, festival attendees weren’t anticipating—and expecting–to livestream or instantly upload their experience. 5G deployments must also account for this with additional sectors to provide a better quality of service. For certain high-profile sports stadiums, sector counts are soaring from the 100s for LTE networks to 600s for 5G networks, highlighting the intensity of the scale of infrastructure expansion required to meet demand. Considering major in-building wireless deployments require roughly 15 or more RUs per sector, that’s a significant number of additional RUs, passive components, and feet of cable. The increase in (and downsizing of) sectors is also why LPRs are required to supplement HPRs and MPRs and provide additional capacity with a low enough power level to avoid interfering with other sectors. Passives May Be Outdated For Higher Frequencies Passive components—including splitters, couplers, and connectors—must also be upgraded to support the higher 5G frequencies. Many components in existing LTE deployments were not designed with 5G frequency
CABLING CHANGES: FROM COAX- DOMINANT TO FIBER-DOMINANT
The approach to cabling for 5G in-building deployments is also undergoing significant changes. For LTE networks, using coaxial cables was a primary option because cov- erage was prioritized over capacity. Lower frequencies like 600, 700, and 800 MHz can travel long distances over coaxial cable without attenuation and upfront install- ation is cheaper because more specialized labor is required to splice optical fiber.
Whereas FDD utilizes two separate streams for uplink (UL) and downlink (DL), TDD uses a single stream for both UL and DL, effectively cutting bandwidth in half.
RF Attenuation - Coaxial Cable vs. Optical Fiber (to 40GHz)
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FIGURE 2: RF Attenuation for optical fiber and coaxial cable. Source: Optical Zonu Corporation.
FIGURE 1: iBwave digital network plan for a baseball stadium. Source: Advanced RF Technologies, Inc. (ADRF).
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ICT TODAY
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