Dynamic Spectrum Access Decisions. George F. Elmasry

Dynamic Spectrum Access Decisions - George F. Elmasry


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Schematic illustration of the 5G FD communications with different stages of noise cancellation.

      Let us consider the following aspects of SI cancellation with FD communications that makes DSM more efficient and possible with the higher frequency bands 5G is utilizing:

      1 Directionality. 5G beam forming relying on MIMO antenna technology means the signal is as narrow as possible where the spectrum is concentrated to the receiving node, with minimal spectrum leaks to other transmitting and receiving node pairs using the same frequency.

      2 5G MIMO antennas implement SI cancellation using multipath fading analysis stages that reach up to 20 dB gain at both the transmitting and receiving antenna. This is shown in Figure 6.9 as the MIMO antenna cancellation.

      3 After using a low noise amplifier, the receiver implements further analog noise cancellation of the RF signal.

      4 After the analog to digital converter, the 5G receiver further implements other digital signal noise cancellation techniques.

Schematic illustration of the 5G protocol stack.

      The reader is encouraged to explore antenna design literature for more details about how 5G MIMO antenna interference cancellation is achieved in the mm‐wave range, which is beyond the scope of this book. However, the next chapter introduces some MIMO techniques that can be considered for adapting 5G for military communications systems.

       energy conservation of end‐user devices

       leveraging the fact that 5G networks can be dense

       avoiding information redundancy

       optimizing resource utilization with heterogeneous networks overlay

       the consideration that end‐use devices can connect to each other with device‐to‐device (DTD) communications protocols.

      One of the core concepts in 5G is the use of a spectrum agent (SA) in order to offload some of the burdens of spectrum sensing and fusion away from the 5G end‐user devices. Notice that 5G can use both licensed and unlicensed spectrum, making it important to detect what frequency bands other communication systems operating in the same geographical location are using.

Schematic illustration of the compound overlay of 5G entities in a 5G deployment.

      1 Periodically detect spectrum utilization in the area and decide if an available licensed band can be used or if an unlicensed band must be used. This decision is based on the SA periodically detecting and analyzing spectrum utilization in the area. Here, the SA is acting as a spectrum fusion center, deciding spectrum availability and broadcasting it to the end users in the area.

      2 Not perform fusion and rely on the macrocell as the fusion center where all the SAs, femtocells and picocells send the macrocell their own spectrum sensing information and the macrocell performs the fusion and send the fusion results to the SAs, femtocells, and picocells.16

      In any case, the SA would respond to the spectrum access service request from the end user with a frequency band it can use regardless of whether that band is licensed or unlicensed, and regardless of whether the decision is made by the SA or the macrocell.

      Note that 5G standards give the service provider flexibility in how to implement spectrum sensing, how to fuse sensing data, and how to create decision. A different hybrid form of local, cooperative distributed, and centralized17 spectrum sensing technique can


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