A New Capacity Result for the Z-Gaussian Cognitive Interference Channel

This work proposes a novel outer bound for the Gaussian cognitive interference channel in strong interference at the primary receiver based on the capacity of a multi-antenna broadcast channel with degraded message set. It then shows that for the Z-channel, i.e., when the secondary receiver experiences no interference and the primary receiver experiences strong interference, the proposed outer bound not only is the tightest among known bounds but is actually achievable for sufficiently strong interference. The latter is a novel capacity result that from numerical evaluations appears to be generalizable to a larger (i.e., non-Z) class of Gaussian channels

On the Capacity of the Two-user Gaussian Causal Cognitive Interference Channel

This paper considers the two-user Gaussian Causal Cognitive Interference Channel (GCCIC), which consists of two source-destination pairs that share the same channel and where one full-duplex cognitive source can causally learn the message of the primary source through a noisy link. The GCCIC is an interference channel with unilateral source cooperation that better models practical cognitive radio networks than the commonly used model which assumes that one source has perfect non-causal knowledge of the other source's message. First the sum-capacity of the symmetric GCCIC is determined to within a constant gap. Then, the insights gained from the derivation of the symmetric sum-capacity are extended to characterize the whole capacity region to within a constant gap for more general cases. In particular, the capacity is determined (a) to within 2 bits for the fully connected GCCIC when, roughly speaking, the interference is not weak at both receivers, (b) to within 2 bits for the Z-channel, i.e., when there is no interference from the primary user, and (c) to within 2 bits for the S-channel, i.e., when there is no interference from the secondary user. The parameter regimes where the GCCIC is equivalent, in terms of generalized degrees-of-freedom, to the noncooperative interference channel (i.e., unilateral causal cooperation is not useful), to the non-causal cognitive interference channel (i.e., causal cooperation attains the ultimate limit of cognitive radio technology), and to bilateral source cooperation are identified. These comparisons shed lights into the parameter regimes and network topologies that in practice might provide an unbounded throughput gain compared to currently available (non cognitive) technologies.Comment: Under second round review in IEEE Transactions in Information Theory - Submitted September 201

Transmit Precoding for Interference Exploitation in the Underlay Cognitive Radio Z-channel

This paper introduces novel transmit beamforming approaches for the cognitive radio (CR) Z-channel. The proposed transmission schemes exploit non-causal information about the interference at the SBS to re-design the CR beamforming optimization problem. This is done with the objective to improve the quality of service (QoS) of secondary users by taking advantage of constructive interference in the secondary link. The beamformers are designed to minimize the worst secondary user's symbol error probability (SEP) under constraints on the instantaneous total transmit power, and the power of the instantaneous interference in the primary link. The problem is formulated as a bivariate probabilistic constrained programming (BPCP) problem. We show that the BPCP problem can be transformed for practical SEPs into a convex optimization problem that can be solved, e.g., by the barrier method. A computationally efficient tight approximate approach is also developed to compute the near-optimal solutions. Simulation results and analysis show that the average computational complexity per downlink frame of the proposed approximate problem is comparable to that of the conventional CR downlink beamforming problem. In addition, both the proposed methods offer significant performance improvements as compared to the conventional CR downlink beamforming, while guaranteeing the QoS of primary users on an instantaneous basis, in contrast to the average QoS guarantees of conventional beamformers

Da’wah approach to the strawberry generation: A study on Yuk Ngaji TV channel

The strawberry generation, Generation Z, has much potential but a fragile mentality like a strawberry, even though Indonesia will get a demographic bonus at a productive age. This is the responsibility of da'wah because it is part of the object of da'wah. YukNgaji TV is a channel that seeks to overcome the problems of millennial teenagers. The research aims to examine the da'wah approach of the YukNgaji TV channel for the strawberry generation using a content analysis approach, where data is collected using documentation and observation techniques. The findings were that the preacher of the channel was chosen from Generation Z (still young), an influencer with advanced knowledge. The da’wah method uses casual sharing discussions, lectures, inspirational stories, and brainstorming. The YouTube media is packaged with live streaming and live events and posting da'wah content, which contains themes of youth, morals, and relationships for the strawberry generation. The effects on the strawberry generation can be cognitive and affective, but further investigation is needed regarding the behavioral effects of the strawberry generation. In this way, the study can contribute to developing preaching approaches that are always required to be dynamic. ***Generasi strawberi merupakan generasi Z yang memiliki banyak potensi, namun memiliki mental rapuh seperti layaknya buah strawberi, padahal Indonesia akan mendapatkan bonus demografi di usia yang produktif. Hal tersebut menjadi tanggungjawab dakwah, karena menjadi bagian dari objek dakwah. YukNgaji TV menjadi channel yang berupaya untuk mengatasi permasalahan remaja milenial ini. Tujuan penelitian untuk mengkaji pendekatan dakwah channel YukNgaji TV bagi generasi strawberi dengan menggunakan pendekatan content analysis, dimana data dikumpulkan dengan teknik dokumentasi dan observasi. Temuannya adalah bahwa pada penelitian channel dakwah ini, berbagai pendekatan dakwah digunakan untuk menjawab persoalan dari generasi strawberi. Pendakwah dipilih dari generasi Z (masih muda), seorang influencer yang memiliki keilmuan yang mumpuni. Metode dakwah dilakukan dengan diskusi sharing santai, ceramah, cerita inspiratif dan brainstorming yang jarang dipakai didunia dakwah. Media pengantar pesan dakwah melalui youtube yang dikemas dengan live streaming dan live event serta postingan konten dakwah, yang berisikan tema keremajaan dan akhlak serta pergaulan bagi generasi strawberi. Efek bagi generasi strawberi ini dapat berupa kognitif dan afektif, namun perlu pendalaman terkait efek behavioral bagi generasi strwaberi. Dengan demikian studi dapat berkontribusi bagi pengembangan pendakatan dakwah yang dituntut untuk selalu dinamis

Effective Capacity in Cognitive Radio Broadcast Channels

In this paper, we investigate effective capacity by modeling a cognitive radio broadcast channel with one secondary transmitter (ST) and two secondary receivers (SRs) under quality-of-service constraints and interference power limitations. We initially describe three different cooperative channel sensing strategies with different hard-decision combining algorithms at the ST, namely OR, Majority, and AND rules. Since the channel sensing occurs with possible errors, we consider a combined interference power constraint by which the transmission power of the secondary users (SUs) is bounded when the channel is sensed as both busy and idle. Furthermore, regarding the channel sensing decision and its correctness, there exist possibly four different transmission scenarios. We provide the instantaneous ergodic capacities of the channel between the ST and each SR in all of these scenarios. Granting that transmission outage arises when the instantaneous transmission rate is greater than the instantaneous ergodic capacity, we establish two different transmission rate policies for the SUs when the channel is sensed as idle. One of these policies features a greedy approach disregarding a possible transmission outage, and the other favors a precautious manner to prevent this outage. Subsequently, we determine the effective capacity region of this channel model, and we attain the power allocation policies that maximize this region. Finally, we present the numerical results. We first show the superiority of Majority rule when the channel sensing results are good. Then, we illustrate that a greedy transmission rate approach is more beneficial for the SUs under strict interference power constraints, whereas sending with lower rates will be more advantageous under loose interference constraints.Comment: Submitted and Accepted to IEEE Globecom 201