A Novel Theoretical Framework for Integrated Sensing and Communication Systems in Nigerian Smart City Infrastructure

Integrated sensing and communication systems enable dual-function waveforms that simultaneously perform wireless sensing functions such as radar detection and environmental mapping while delivering data communications services, sharing spectral and hardware resources to dramatically improve efficiency in spectrum-congested smart city environments. The theoretical framework for ISAC system design under the urban electromagnetic environment conditions of Nigerian smart city deployments has not been previously developed. This doctoral study develops a novel theoretical framework for ISAC systems targeting Nigerian smart city infrastructure applications, with specific focus on the dual-function requirements of urban traffic monitoring and vehicular communications in Abuja's smart city pilot zones. An original signal design framework is derived that jointly optimizes the communication mutual information and radar sensing Fisher information for dual-function ISAC waveforms under transmit power and spectral mask constraints applicable to the NCC frequency allocations relevant to smart city deployments. The fundamental trade-off boundary between communication rate and sensing accuracy achievable by ISAC waveforms under the derived constraints is characterized analytically, constituting an original contribution to the ISAC theoretical literature. A precoding design algorithm achieving operation on the communication-sensing Pareto frontier is derived and its convergence under realistic urban channel conditions is proved. Hardware-in-the-loop validation using a software-defined radio testbed in a controlled urban environment demonstrates sensing range accuracy within 3.2 meters and communication throughput within 8% of the theoretical benchmark. The doctoral framework provides the first ISAC system theoretical foundation grounded in Nigerian regulatory and urban environment constraints. Keywords: integrated sensing and communication, ISAC, smart city, radar communication, Abuja.