An Underwater Cooperative Spectrum Sharing Protocol for a Centralized Underwater Cognitive Acoustic Network

Abstract

To efficiently utilize nonexclusive underwater acoustic frequencies, we propose an Underwater Cooperative Spectrum Sharing (UCSS) protocol for a centralized underwater cognitive acoustic network that mainly consists of two parts. In the first part, to check the random occurrence of interferers periodically, the time domain is divided into frames that consist of a sensing and a non-sensing sub-frame. Then, we set the ratio of the two sub-frames to enhance the sensing rate via simulations. As a result, there exists the upper limit of the ratio, which can be used for determining the proportion of the sensing time within a frame. The second part is to design two heuristic resource allocation (RA) algorithms. One is a multiround RA (MRRA), where a central entity allocates a data channel (i.e., resource) to a CU each round so that multiple rounds are executed until no CUs need to be allocated or there is a lack of data channels. The other is a single-round RA (SRRA), where a CU is allocated to as many data channels as its QoS within a round. We also specify four rules to determine the allocation order of the CUs: random, fixed, high-QoS-based, and low-channel allocation-rate-based. In this study, we investigate the best RA allocation order pair supporting the highest channel allocation rate and fairness index via extensive simulations. It is shown that the MRRA outperformed the SRRA, regardless of allocation orders at any conditions, and the random and low-channel allocation-rate-based allocation orders with MRRA supported the best performance. In particular, even without the optimization process, the MRRA guarantees more than 95% fairness.

Direct-Conversion Spectrum Sensor Impaired by Symmetric α-Stable and α-Sub-Gaussian Noises

“…The main objective of [8] is to improve the accuracy of spectrum sensing by improving the use of the underwater frequency spectrum through a model based on energy detection with two thresholds and hard decision fusion, preventing attacks from malicious users. In [31], a protocol for cooperative underwater spectrum sharing for a centralized UCAN is proposed, consisting of two parts. The first one checks the random occurrence of interference periodically, by dividing the time domain into frames consisting of sensing and non-sensing subframes.…”

A Channel Allocation Method Considering the Asymmetry of Available Channels for Centralized Underwater Cognitive Acoustic Networks

“…The development of UCAN technologies is challenging because of the following differences from CRNs, as specified in [ 14 ]: While there are well-known channel models in CRNs, predicting the channel model in UCANs is difficult due to the presence of unpredictable multi-paths and diverse noises; CRNs have a channel plan that defines the center frequency, channel index, and bandwidth, while in UCANs, the acoustic frequency band is an open spectrum where overlapping use of frequencies is inevitable; In CRNs, primary and secondary users are clearly differentiated by the license policy, while in UCANs, there are unpredictable and uncontrollable interferers due to the lack of a standardized channel plan; In CRNs, any signal can be decoded due to the standardized signaling format, while in UCANs, most signals from neighboring interferers are uninterpretable. …”

“…In the literature, the majority of works focus on proposing efficient resource allocation methods that assign a CU to network resources (e.g., acoustic frequency, data rate, and transmission power). In [ 14 ], previous UCAN studies are categorized into three groups: single resource allocation, joint resource allocation, and other than resource allocation. We have included additional existing works and have summarized their characteristics in Table 1 .…”

“…In particular, Ref. [ 14 ] defined the concept of interferers (i.e., NCUs) and fragmented time domain units, and derived important considerations of spectrum sharing for centralized UCANs. These considerations can be used to develop other protocols, such as spectrum mobility or channel access.…”

“…Unlike prior optimization-based approaches, Ref. [ 14 ] also proposed a heuristic spectrum sharing protocol, which consists of how to set the allocation order of CUs and the way in which to assign channels to them. Simulation results showed that the combination of a low channel allocation rate (CAR)-based allocation priority and multi-round resource allocation (MRRA) outperformed other pairs in terms of CAR and fairness.…”