Modeling unreliable LSA operation in 3GPP LTE cellular networks

2019

IEEE Access

In licensed shared access (LSA) systems, the protection of the incumbent in the shared spectrum may degrade the spectrum and energy efficiency of the licensee. In this paper, we examine the optimization of these two performance metrics in a LSA vertical sharing scenario between an airport incumbent, and a mobile network operator licensee. Considering a restriction zone of a pre-defined radius, we derive the probability of the incumbent's interference threshold and then formulate a power allocation scheme as a multi-objective optimization of both energy and spectrum efficiency. We then adopt the weighted sum method to convert this multi-objective optimization into a single objective optimization and convert that into a quasi concave optimization problem. The optimum power allocation is then obtained using fractional programming. We further investigate the impact of various critical operational parameters in conjunction with the two performance metrics. Simulation results indicate a significantly improved energy efficiency in the licensee network as well as the spectrum efficiency comparable to even when the LSA spectrum utilization is unrestricted by the incumbent's maximum interference threshold. Furthermore, we show that with careful selection of the licensee eNodeB coverage radius, transmit power, and users number per eNodeB coverage area, one can engineer the best possible trade-off between the spectrum and energy efficiency.

Section: A Related Workmentioning

confidence: 99%

On the Spectrum and Energy Efficiency in Dynamic Licensed Shared Access Systems: A Multiobjective Optimization Approach

2019

IEEE Access

“…In [7] spectrum resource allocation in the cellular band between a cellular network and an LSA system is investigated, and a system model based on homogenous queues is used to analyse the performance. Queueing theory is also used in [8] to model the LSA operation. The authors of [9] presented experimental evaluations of dynamic LSA operation in an LTE testbed.…”

Section: Introductionmentioning

confidence: 99%

“…As it is seen, most of the previous works on the LSA are either focused on modeling the spectrum utilisation for a given setting, see, e.g., [8], [10], [13], or evaluate performance metrics such as the interruption probability, blocking probability, average number of connected users, service failure, mean bit rate, etc [7], [8], [10], [13]. In contrast with the previous works, here our main objective is to explore techniques for optimizing the system spectrum efficiency, especially during the time intervals in which the LSA band is not available while ensuring the allowable interference threshold is not exceeded.…”

Section: Introductionmentioning

confidence: 99%

Maximum Achievable Sum Rate in Highly Dynamic Licensed Shared Access

2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring)

2019

In this paper, we consider a power allocation scheme that maximizes the sum spectral efficiency of the licensee in a dynamic Licensed Shared Access (LSA) system. In particular, our focus is on the time intervals in which the incumbent system is active in the spectrum. We derive an expression for the interference distribution of the licensee, e.g., a mobile network operator, utilizing a spectrum belonging to an airport incumbent under the LSA spectrum sharing. Formulating an optimization problem to maximize the sum spectrum efficiency subject to the interference threshold constraint at the licensee, we then show its convexity, and obtain its optimal solutions. We further investigate the impact of sum rate maximization on the fairness of network resource allocations. Simulation results show a significant gain in the achievable spectrum efficiency, especially during the intervals in which the incumbent system is active in the LSA band. This paper provides quantitative insights on the maximum achievable sum rate in an LSA system in which both the licensee and the incumbent systems are active at the same time.

“…Against this background, several studies have investigated the effect of the incumbent's revocation of access right on the licensee's system performance. Investigating an LSA scheme between an airport incumbent and a mobile network operator (MNO) licensee, [2] examines the service time unavailability and the resulting packet loss for the licensee system as a result of the incumbent's revocation of the licensee's spectrum access right. Adopting the queuing theory concept, the authors of [3] model the LSA licensee network (an MNO) as a two server system, one reliable and the other unreliable.…”

Section: Introductionmentioning

confidence: 99%

On the Achievable Energy Efficiency in Dynamic Licensed Shared Access

2019 IEEE Globecom Workshops (GC Wkshps)

2019

The licensed shared access (LSA) promises to be a viable alternative solution to the well-reported spectrum underutilization. The higher priority of the incumbent in the spectrum sharing arrangement implies that the licensee access to the spectrum can be revoked or restricted at any time. This has been observed to result in degradation of some critical performance metrics of the latter. In this paper, we investigate the effect of this on the energy efficiency (EE) of an LSA sharing between an airport incumbent and a mobile network operator licensee. We formulate expressions for the operating transmit power of the licensee when its spectrum access right is revoked/restricted in both the uplink and downlink transmission directions. We then propose a power allocation scheme that maximizes the EE of the licensee during these time intervals in which the licensee operating transmit power is constrained by the incumbent system's utilization of the spectrum. We further provide analytical discussion on how the achievable EE during this time compares to when the licensee access to the spectrum is free of any restriction from the incumbent. The results obtained shows that while the EE suffers degradation in the uplink when the licensee spectrum access right is restricted, there is no noticeable difference in the achievable EE in the downlink direction. Furthermore, in the uplink, the optimal power allocation provides better EE even than when the spectrum is free especially at lower transmit power and channel number, while in the downlink, the optimal power allocation EE is consistently better than the free spectrum EE.