On Stable Throughput of Cognitive Radio Networks With Cooperating Secondary Users

Kulkarni, Kedar; Banerjee, Adrish

doi:10.1109/tcomm.2016.2597857

Cited by 5 publications

(12 citation statements)

References 34 publications

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Section: B Related Workmentioning

confidence: 99%

“…In [18], the SUs cooperate with the PU by assisting retransmissions of failed packets using distributed orthogonal space-time block code; however, knowledge of the PU packet is not exploited at the SU receiver to perform interference cancellation. Differently from [18], we assume no cooperation with the PU at the SU transmitter, but only interference cancellation at the SU receiver. Differently from these works, in this paper we consider multiple retransmissions (in contrast to [15], [16]), and we exploit the redundancy of the ARQ process (in contrast to [8], [18]).…”

Section: B Related Workmentioning

confidence: 99%

“…practical aspects related to imperfect sensing can be investigated using tools developed in [18], [20]. While non-causal knowledge of the PU packet is assumed in [17], in our work we model the dynamic acquisition of the PU packet at the SU receiver, which is of more practical interest.…”

Section: B Related Workmentioning

confidence: 99%

“…P s may be based on an interference temperature threshold experienced at the PU receiver [19], and can be estimated using techniques developed in [11]. We assume that the SU knows the signal characteristics of the PU and is accurately synchronized with the PU system, as commonly assumed in the literature [5], [8], [15], [16], [18].…”

Section: System Modelmentioning

confidence: 99%

“…where D is the horizon duration, the expectation is taken with respect to the sequence {a S,t , t≥0} generated by the access policy µ, and the decoding outcomes at SUrx and PUrx. This metric is equivalent to the "stable throughput," which guarantees stability in a systems where packets generated in upper layers are stored in queues before transmission [18]. Since ρ a S,t =ρ 0 +a S,t (ρ 1 −ρ 0 ), one can rewriteT…”

Section: Optimization Problemmentioning

confidence: 99%

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Optimal Spectrum Sharing With ARQ-Based Legacy Users Via Chain Decoding

Michelusi

2018

IEEE Trans. Wireless Commun.

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This paper investigates the design of access policies in spectrum sharing networks by exploiting the retransmission protocol of legacy primary users (PUs) to improve the spectral efficiency via opportunistic retransmissions at secondary users (SUs) and chain decoding. The optimal policy maximizing the SU throughput under an interference constraint to the PU and its performance are found in closed form.It is shown that the optimal policy randomizes among three modes: Idle, the SU remains idle over the retransmission window of the PU, to avoid causing interference; Interference cancellation, the SU transmits only after decoding the PU packet, to improve its own throughput via interference cancellation;Always transmit, the SU transmits over the retransmission window of the PU to maximize the future potential of interference cancellation via chain decoding. This structure is exploited to design a stochastic optimization algorithm to facilitate learning and adaptation when the model parameters are unknown or vary over time, based on ARQ feedback from the PU and CSI measurements at the SU receiver.It is shown numerically that, for a 10% interference constraint, the optimal access policy yields 15% improvement over a state-of-the-art scheme without SU retransmissions, and up to 2× gain over a scheme using a non-adaptive access policy instead of the optimal one. July 2, 2018 DRAFT arXiv:1801.07877v2 [cs.IT] 29 Jun 2018 2 legacy users (primary users, PUs) and opportunistic users (secondary users, SUs) capable of autonomous reconfiguration by learning and adapting to the communication environment [4]. A central question is: how can opportunistic users leverage side information about nearby legacy users (e.g., activity, channel conditions, protocols employed, packets exchanged [5]) to opportunistically access the spectrum and improve their own performance, with minimal or no degradation to existing legacy users [6]? In this paper, we address this question in the context of the retransmission protocol employed by PUs. We consider a wireless network composed of a pair of PUs and a pair of SUs. The PU employs Type-I HARQ [7] to improve reliability, which results in replicas of the PU packet (re)transmitted over subsequent slots, henceforth referred to as ARQ window. With the scheme developed in [8], the SU receiver attempts to decode the PU packet independently in each slot, and replicas of the PU packet are not exploited; thus, in the example of Fig. 1, no SU packets can be decoded with the scheme [8]. However, the SU may leverage these replicas to improve its own throughput via interference cancellation. In [9], we have investigated a scheme, termed backward interference cancellation (BIC), where the SU receiver decodes the PU packet and removes its interference to achieve interferencefree transmissions over the entire ARQ window of that PU packet. In the example of Fig. 1, this scheme allows the SU receiver to decode packet S4, after removing the interference of P2, decoded in slot 5, thus outperforming [8].In [10], we have...

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Section: B Related Workmentioning

confidence: 99%