## 1 Introduction  
Mobile Ad Hoc Networks (MANETs) have evolved from a specialized area of study into a ubiquitous element of modern wireless communications, playing a crucial role in the development of smart cities. Initially engineered for tactical military communications, their adaptability and resilience have expanded their applications to include disaster recovery, remote sensing, and complex multi-layered Internet of Things (IoT) ecosystems--key components of urban infrastructure. As the urban environment becomes increasingly connected, Vehicular Ad Hoc Networks (VANETs) emerge as a critical subset of MANETs, specially designed for the fast-moving nature of vehicular networks [1; 2; 3]. VANETs enable vehicles to communicate with each other and with roadside infrastructure, facilitating not only improved traffic management but also enhancing safety and supporting a range of services from navigation to automated driving in smart cities [4; 5; 6]. The impending arrival of Sixth Generation (6G) wireless technologies is poised to revolutionize the context of both MANETs and VANETs, particularly in urban settings. Unlike its predecessors, 6G represents a fundamental shift in wireless communication capabilities rather than a mere incremental upgrade. This upcoming technological leap is expected to dramatically reshape the extent and complexity of these network types within city environments. It promises ultra-low latency levels, down to the sub-millisecond range, unprecedented data rates reaching terabits per second, and near-perfect reliability [7; 8]. These features are expected to support futuristic applications crucial for smart cities, such as real-time augmented and virtual reality, machine-to-machine communications, ultra-reliable low-latency services, and the tactile Internet, which have extreme demands on network performance. Moreover, resource allocation, a challenge already significant in 5G, continues to be a key issue in 6G networks. Recent studies have leveraged Particle Swarm Optimization (PSO) to address non-convex optimization problems in resource allocation, demonstrating that PSO can outperform traditional algorithms like Genetic Algorithms in achieving convergence and cost minimization [9]. Advancements in MIMO technology, such as circularly polarized (CP) high-isolation MIMO antennas, have been demonstrated to improve S-parameters, mutual coupling, and channel capacity, making them well-suited for WLAN applications in the 5 GHz spectrum, which aligns with the goals of future VANETs and MANETs [10]. However, the transition to 6G introduces significant challenges, particularly for the inherently complex and dynamic networks like MANETs and VANETs in urban settings [11; 12; 13]. Traditional routing protocols, such as Dynamic Source Routing (DSR), are proving inadequate in this context. Designed in an era where network demands were less stringent, these protocols often rely on simplistic metrics like hop count for route selection, which is insufficient in the multi-dimensional Quality of Service (QoS) requirements of 6G, where latency, bandwidth, reliability, and energy efficiency are critical factors that must be simultaneously optimized [14; 15; 16; 17]. To address these challenges, we introduce MMS-DSR (Multi-Metric Scoring Dynamic Source Routing), a novel modification and enhancement of the traditional DSR protocol, specifically designed for the complex requirements of 6G-enabled MANETs and optimized for the high-velocity, highly mobile environments of VANETs in smart cities. MMS-DSR incorporates several innovative features, including the utilization of Massive MIMO technologies and the IEEE 802.11 ax standard [18]. Massive MIMO, with its capacity to manage multiple transmit and receive antennas, offers significant improvements in data rates and link reliability. The IEEE 802.11 ax standard, conversely, provides advancements in network efficiency and capacity, particularly in environments with a high density of connected devices.