Multihop mobile wireless networks is a subject of intense research interest for next generation wireless systems. As we move towards fourth generation (4G) networks, high data-rates of the order of 100 Mbps can be achieved only over short distances. A multihop network has smaller transmission distance as compared to an equivalent single-hop network. This enables the radio terminals that are spatially well-separated from each other to reuse the same resources when the resulting interferences are not too severe. In this dissertation, the multihop network design is studied for two different kinds of systems: multihop ad hoc network and multihop hybrid cellular network. In the first part of the thesis work, a multihop ad hoc network is analyzed in detail and the system capacity is computed. However, the calculation of optimal resource allocation that would maximize the system capacity is found to be an NP-hard problem. Considering this complexity, a random data hopping technique has been proposed over a time-slot (TS) partitioned system in order to improve the system capacity of the network. It has been found that the granularity of the TS(s) can be increased by reducing the duration of each TS. Significantly, applying the random data hoping technique over the TS partitioned system results in an increase in the system capacity without any additional increase in the computational complexity. In the second part of the thesis work, a multihop hybrid cellular network is studied. It is known that optimal resource allocation in a multihop cellular network is again a NP-hard problem. A novel cluster-based design is proposed in this work for a 2-hop cellular network, whereby, two pairs communicate simultaneously in every hexagonal cell, at any time instant. Such a cluster-based 2-hop design provides an increase in the spatial resource reuse and hence results in a much higher system capacity as compared to three standard benchmark algorithms for 2-hop cellular networks.