In a traditional electrical grid, distribution system is deployed to deliver electrical energy to medium voltage and Low Voltage (LV) consumers. To achieve full control on generation and consumption of electricity at distribution level, automation of the electrical infrastructure through an Information and Communication Technology (ICT) infrastructure is prime focus of prospective Smart Grid (SG). A communication system for highly pervasive nodes (such as smart meters, and distributed energy resources) in Neighbourhood Area Network (NAN) of SG becomes critical if virtual power plant is expected to manage grid resources at distribution level. This requires accurate link budget assessment for chosen wireless communication technology. Furthermore, the choice of wireless technology is also critical. To estimate the link budget in NAN implementing German Advanced Metering Infrastructure (AMI) system, a path loss model has been developed after comprehensive measurement campaigns conducted in the suburban area of Germany. The proposed model estimates link budget at 200 MHz, 434 MHz, 868 MHz and 2.4 GHz frequency bands for outdoor-to-outdoor and outdoor-to-indoor communication links. Furthermore, wireless communication technology for Sub-1 GHz (S1G), IEEE 802.11ah, has been evaluated in simulation for its feasibility in German AMI networks, where this AMI has also been assumed to be heterogeneous in terms of traffic demand and location of devices in the network. Two algorithms for network slicing have also been suggested for three-tier grouping of network devices in IEEE 802.11ah. Finally, the algorithms have been evaluated on the Restricted Access Window (RAW) grouping and page slicing approaches of IEEE 802.11ah in comparison with legacy access mechanism.