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1. TOWARD TRANSPARENT COEXISTENCE FOR MULTIHOP
SECONDARY COGNITIVE RADIO NETWORKS
ABSTRACT
The dominate spectrum sharing paradigm of today is interference avoidance, where a
secondary network can use the spectrum only when such a use is not interfering with the primary
network. However, with the advances of physical-layer technologies, the mindset of this
paradigm is being challenged.This paper explores a new paradigm called “transparent
coexistence” for spectrum sharing between primary and secondary nodes in a multihop network
environment. Under this paradigm,the secondary network is allowed to use the same spectrum
simultaneously with the primary network as long as their activities are “transparent” (or
“invisible”) to the primary network. Such transparency is accomplished through a systematic
interference cancelation (IC) by the secondary nodes without any impact onthe primary network.
Although such a paradigm has been studied in the information theory (IT) and communications
(COMM) communities, it is not well understood in the wireless networking community,
particularly for multihop networks. This paper offers an in-depth study of this paradigm in a
multihop network environment and addresses issues such as scheduling (both in frequency
channels and time slots) and IC (to/from primary network and within the secondary network).
Through a rigorous modeling and formulation, problem formulation, solution development, and
simulation results, we show that transparent coexistence paradigm offers significant
improvement in terms of spectrum access and throughput performance as compared to the
current prevailing interference avoidance paradigm.