Cognitive Cellular Networks Research Articles

Reversed Stackelberg bandwidth-sharing game for cognitive multi-hop cellular networks

Multi-hop relaying cellular network (MCN) is a recently proposed architecture to preserve the advantages of traditional single-hop cellular networks and ad hoc relaying networks. In MCNs, efficient bandwidth management plays an important role in determining network performance. In this study, a new cognitive radio bandwidth-sharing scheme is proposed based on the reversed Stackelberg game model. In the proposed scheme, base station (BS) and relay stations (RSs) are hierarchically interconnected and interacting with one another to effectively share the wireless bandwidth. By using a trust model, the BS appropriately reacts to selfish RSs to maximise network performance. This approach can promote cooperation with respect to adaptive bandwidth allocation. With a simulation study, it is demonstrated that the proposed scheme can approximate an optimised solution under widely diverse traffic load intensities.

Secondary spectrum access and cell-edge coverage in cognitive cellular networks

This study focuses on the problem of cell-edge user coverage in the context of cognitive radio networks operating within the vicinity of primary cell borders. Two strategies are introduced such that the primary cell-edge users get assisted by the cognitive base station (BS) to receive a consistent quality of service (QoS) because of their long distance from the primary BS. In return, the cognitive BS is rewarded by using the same spectrum that has already been allocated to the primary users' link to serve a group of cognitive users. In the first strategy that we call cooperative, the cognitive BS relays the primary cell-edge users' data, sent by the primary BS, through spatial multiplexing and beamforming, while transmitting towards its cognitive users. In the second strategy that we call soft interference shaping, the cognitive BS serves cognitive users as well as primary cell-edge users by spatial multiplexing and beamforming, while forming controlled nulls towards the primary users located outside but within the close vicinity of the cognitive cell border. This technique is done to avoid the interference towards the primary users surrounding the cognitive cells border.

A Comment on "Performance Analysis of Uplink Cognitive Cellular Networks with Opportunistic Scheduling"

An exact closed-form bit-error-rate (BER) expression is derived for the scheduled cognitive user (CU) in the uplink cellular networks with opportunistic scheduling considered by Li. Simulation results corroborate the theoretical analysis.

Energy-Efficient and Low-Complexity Schemes for Uplink Cognitive Cellular Networks

This Letter proposes two types of energy-efficient and low-complexity schemes for uplink cognitive cellular networks. In the considered system, both cognitive users (CUs) and primary user (PU) share the same base station (BS). Under an outage probability protection criterion for the PU, we firstly propose a round-robin CU scheduling scheme and analytically show its achieved signal-to-interference ratio statistics at the BS, from which it is observed that the round-robin scheduling is much more energy-efficient than opportunistic scheduling to achieve the same mean capacity and bit error rate. Inspired by this interesting observation, a statistics-based CU scheduling scheme is also presented, whose energy-efficiency is further improved.

Performance Analysis of Uplink Cognitive Cellular Networks with Opportunistic Scheduling

In this letter, we investigate the performance of uplink cognitive cellular networks with opportunistic scheduling with respect to the mean capacity and the average bit error rate (BER) of the scheduled cognitive user (CU). In the considered system, both CUs and the primary user (PU) share the same base station (BS). In contrast to existing CU scheduling schemes, the CU which causes the minimum interference to the PU is selected for transmission. Besides, the transmit power of the selected CU should also satisfy the outage probability requirement of the PU. An interesting observation is that both the mean capacity and the upper bound on the average BER of the scheduled CU are independent of the number of CUs and the transmit power of the PU.