  5G network is envisioned to deploy a massive Internet-of-Things (IoTs) with
requirements of low-latency, low control overhead and low power. Current 4G
network is optimized for large bandwidth applications and inefficient to handle
short sporadic IoT messages. The challenge here spans multiple layer including
the radio access and the network layer. This paper focus on reusing CDMA access
for IoT devices considering event-driven and latency sensitive traffic profile.
We propose a PHY/MAC layer design for CDMA based communication for low power
IoT devices. We propose and evaluate coexisting operation of CDMA based IoT
network in presence of the exiting LTE network. Our proposed design will
integrate IoT traffic with legacy system by minimal modification at the edge
network, essentially eNodeB. We show that the underlay CDMA IoT network meets
IoT data traffic requirements with minimal degradation (3%) in the LTE
throughput. We also implement the proposed design using Software Defined Radios
and show the viability of the proposal under different network scenarios.
