# Multifunction RF Systems for Naval Platforms
## 5 MFRF System Resource Management
### Development and Evaluation of Resource Management Techniques  
Once a suitable modelling and simulation tool has been developed, it would be used to explore the capabilities and limitations of different RAM schemes for a MFRF system. Resource management techniques that have been found to be effective for RRM would be good candidates for initial investigation. If necessary, these RRM techniques may be modified to optimize them for the MFRF system application. Also, new approaches may additionally be developed and tested. The specific configuration and performance characteristics of the MFRF system hardware assets that are under RAM control are key factors in ultimately determining the extent to which resource management techniques can mitigate RF function performance degradation in challenging threat scenarios. Consequently, careful effort would be required in selecting a MFRF system architecture for this study which will be representative of the technology available within the timeline of interest. Based on the discussions in Section 3, a preliminary recommendation is that the modelled baseline MFRF system architecture include the following high-level features:  
* _Separated Rx and Tx arrays_: For the foreseeable future, this is the only configuration that ensures sufficient isolation between Rx and Tx channels to allow simultaneous transmission and reception at the same frequencies, which is a requirement when ES and EA functions are involved. * _Multiband_: Given the bandwidth limitations of a number of the required hardware components, it is prudent to assume a multiband system that covers the full operating frequency range up to 40 GHz with several bands. Examination of currently available technology described in Section 3 suggests that the performance characteristics of key components, namely HPAs, LNAs and ADCs, are good enough now or will be in the near future to support one such band that roughly covers from 4-10 GHz. This frequency range is significant, because it notionally encompasses all of the radar subfunctions (VS, HS and TI), as well as the X-band communication function, and an important part of the operating range for EA and ES functions. Thus, this band provides the greatest potential to yield a challenging overload situation for a RAM, and would consequently be the focus of the resource management study. * _Element-level digitization and subarray-level waveform generation_: The flexibility to arbitrarily partition Rx arrays and digitally form any given number of multiple simultaneous Rx beams from the same part of the AESA are key motivations to using element-level digitization in a MFRF system. Element-level digitization has already been implemented in some commercially available radars, and the continuing strong trend in ADC technology towards higher performance and lower cost suggests that this design feature will be increasingly utilized in the near future. On the other hand, the benefits of element-level waveform generation are not as significant. Utilization of subarray-level waveform generation sacrifices some flexibility in configuring the Tx array, as discussed in Section 3, and requires the insertion of passive phase shifters or TTD circuits in the Tx channels to perform beamforming, but these disadvantages are likely outweighed by the reduction in system cost and complexity achieved by implementing fewer DWGs. The modelling effort would include at least two scenarios-benign and challenging. These are described as follows. * _Benign scenario_: In this baseline scenario, there would be no threats to which the MFRF system would need to respond. Consequently, the only functions activated would be ES, VS/HS radar, and occasionally X-band communications. The RAM would be able to allocate sufficient resources to each of these functions to allow them to operate at full performance. * _Challenging scenario_: A number of threats would be inserted in this scenario to force the activation of EA and TI radar functions in addition to the functions operating in the benign scenario.