WIST: Wi-SUN FAN Protocol Emulation Testbed

摘要

We present a novel emulation testbed design to test wireless protocols in an efficient, realistic, and reproducible manner, and use Wi-SUN Field Area Network (FAN) protocols to demonstrate its efficiency. The testbed provides emulated Layer 2 connectivity for a mesh of wireless nodes without needing to manipulate Layer 1 signals or inject radio frequency interference. An early version of the testbed that relied on a centralized server to forward packets introduced excessive differential delay that interfered with protocol operation. The improved version described in this paper achieves near-simultaneous delivery of a packet to the set of nodes within range of a sender. To provide an emulated delivery mechanism, the testbed uses multicast addressing in an unusual way. Each node is assigned a unique bit position within the multicast address space. Instead of sending outgoing packets to an emulation server, a node forms a multicast address with bits of the address set for all nodes within range, and multicasts the packet. Conceptually, each node is configured to accept a large set of multicast destination addresses that correspond to transmissions from neighbors in the emulated mesh topology. In practice, the testbed achieves packet recognition efficiently, without requiring a network interface to handle large numbers of multicast addresses. As a result, all neighbors of a node in the emulated mesh topology receive a copy of a packet at approximately the same time, like an actual wireless network. The paper also describes a software-defined programmable management system that uses scripted testbed commands to run sequences of tests.