Cognitive Networks Achieve Throughput Scaling of a Homogeneous Network

Abstract

We study two distinct, but overlapping, networks that operate at the same time, space, and frequency. The first network consists of n randomly distributed primary users, which form either an ad hoc network, or an infrastructuresupported ad hoc network with l additional base stations. The second network consists of m randomly distributed, ad hoc secondary users or cognitive users. The primary users have priority access to the spectrum and do not need to change their communication protocol in the presence of secondary users. The secondary users, however, need to adjust their protocol based on knowledge about the locations of the primary nodes to bring little loss to the primary network's throughput. By introducing preservation regions around primary receivers and avoidance regions around primary base stations, we propose two modified multihop routing protocols for the cognitive users. Base on percolation theory, we show that when the secondary network is denser than the primary network, both networks can simultaneously achieve the same throughput scaling law as a stand-alone network. Furthermore, the primary network throughput is subject to only a vanishingly fractional loss. Specifically, for the ad hoc and the infrastructure-supported primary models, the primary network achieves sum throughputs of order n 1/2 and max{n 1/2 , l}, respectively. For both primary network models, for any δ > 0, the secondary network can achieve sum throughput of order m 1/2−δ with an arbitrarily small fraction of outage. Thus, almost all secondary source-destination pairs can communicate at a rate of order m −1/2−δ .

Cognitive radio ad hoc networks for smart grid communications: A disaster management approach

“…In [18], it is shown that under certain assumptions, which are valid in our proposed network model, both secondary and primary networks achieve the same throughput scaling as when the other network is absent. These assumptions include:…”

Achievable transmission capacity of cognitive radio networks with cooperative relaying

“…The capacity of general ad hoc networks has been extensively studied in literature [29,30]. The scaling laws of the throughput and/or delay of coexisting primary and secondary ad hoc networks under various protocol settings have been investigated in [29,[31][32][33]. These works consider fundamentally different problems than our study, which focuses on the achievable transmission capacity (link layer) of cognitive radio networks with cooperative relaying.…”

“…Since the capacity of the secondary user decreases with the increase of the power ratio, we can obtain the following maximum transmission capacity C * AF of the cooperative cognitive network by substituting γ l ps into Equation 32.…”

On the Connectivity and Multihop Delay of Ad Hoc Cognitive Radio Networks

“…The capacity scaling law of CR networks has been analyzed in [4,5,6]. In [4], the authors also derive the capacity-delay tradeoff for a specific routing and scheduling algorithm which is shown to achieve the optimal one for homogeneous networks.…”

“…We use the infinite connected component consisting of communication links 5 in G H (λ S , λ P T , t 0 ) during some primary slot t 0 to construct a path L C from µ to ν such that the multihop delay along this path is independent of the distance d(µ, ν) (see Fig. 4 …”