The method of Opportunistic Data Forwarding (ODF), supporting real time traffic in large scale wireless networks, is studied. The random uncertainties in wireless networking are exploited opportunistically to achieve reliable communications. The ODF is established as a peer-to-peer unicast wireless link module, over long distance, within the architecture framework of Embedded Wireless Interconnect (EWI). In order to provide real-time Quality of Service (QoS), the tradeoff between network energy consumption and end-to-end packet delay is investigated, where the complicated end-to-end optimization problem is statistically recast into an equivalent, but solvable, single hop resource allocation problem, under the long distance asymptotic condition.