Unlicensed Long Term Evolution Research Articles

Enhancement of Opportunistic Co-Occurrence of U-LTE and Wi-Fi/Iot in 5 GHz Using Cognitive Radio

In this modern era, Unlicensed Long-Term Evolution (U-LTE) is the most interested research area to enable its access in 5GHz ISM unlicensed band for increasing data rate and spectral efficiency. The major constraint for accessing these frequencies is being able to coexist with other Wi-Fi/IoT users. Such constraint has been tackled by developing Wi-Fi/IoT by using Cognitive Radio Network (CRN) with two objectives such as deploying the Listen-Before-Talk (LBT) regulatory requirement of radio communication in U-LTE and enhancing their co-existence with Wi-Fi/IoT users in a non-interference manner. However, uplink data transmission was not considered in the unlicensed spectrum usage and also the spectrum efficiency was less. Hence, in this paper, the co-occurrence between LTE and Wi-Fi/IoT using CRN is further enhanced and realized. Initially, the co-occurrence between LTE and Wi-Fi in the unlicensed spectrum is enhanced by proposing efficient spectrum utilization based on Conflict-Tolerant Channel Allocation (CTCA) algorithm that reduces the channel inconsistencies efficiently. Moreover, this algorithm is enhanced to increase the spectrum efficiency and simultaneous transmissions in the similar channel based on an enhanced Cell ON/OFF mechanism which optimizes the resource allocation. Finally, the simulation results show that the performance efficiency of the proposed system compared to the existing in terms of spectrum efficiency, throughput and transmission time delay.

Enhanced LAA for Unlicensed LTE Deployment Based on TXOP Contention

Licensed-assisted-access (LAA) has recently emerged as a heterogeneous network technology to help mitigate the scarcity of licensed spectrum by extending the long-term evolution (LTE) network to unlicensed spectrum. This work proposes an enhanced LAA (eLAA) as a practical technique by exploiting the inherent transmit opportunity (TXOP) reservation via the Clear-to-Send-to-Self (CTS-to-Self) frame in Enhanced Distributed Channel Access (EDCA) to seamlessly integrate eLAA transmission within existing WiFi protocol. Unlike other LAA proposals, our eLAA is non-intrusive to unlicensed WiFi users and beneficial to both eLAA and WiFi networks. To further improve throughput, we analyze and derive an optimized unlicensed resource allocation scheme before deriving several intrinsic properties. Our results demonstrate that tagging CTS-to-Self frames as a higher-priority access category can substantially improve eLAA throughput without seriously degrading the per-user WiFi throughput.

On the Coexistence of LTE-LAA in the Unlicensed Band: Modeling and Performance Analysis.

Long term evolution (LTE) technology leveraging the unlicensed band is anticipated to provide a solution for the challenges stemming from the rapid growth of mobile wireless services, the scarcity of available licensed spectrum, and the expected significant increase in mobile data traffic. Ensuring fair operation in terms of spectrum sharing with current unlicensed spectrum incumbents is a key concern relative to the success and viability of Unlicensed LTE (U-LTE). This paper addresses the problem of modeling and evaluating the coexistence of LTE license-assisted-access in the unlicensed band. The paper presents a novel analytical model using Markov chain to accurately model the LAA listen-before-talk scheme, as specified in the final technical specification 36.213 of 3GPP release 13 and 14. Furthermore, model validation is demonstrated through numerical and simulation results comparison. Model performance evaluation is examined and contrasted with IEEE 802.11 distributed coordination function. Finally, a comprehensive coexistence performance analysis is conducted for both homogeneous and heterogeneous network scenarios and coexistence results are presented and discussed herein.

Enhancing 4G Co-existence with Wi-Fi/IoT using cognitive radio

The advanced cellular network, long term evolution (LTE) that presently operates in licensed spectrum has been extended to unlicensed LTE (U-LTE) to improve data rate and spectral efficiency by utilizing unlicensed spectrum. Carrier aggregation of 3GPPLTE-A supports the aggregation of licensed and unlicensed spectrum in small and femto cells to provide better user experience. The proposed work consists of two objectives, first to accomplish the listen-before-talk (LBT) regulatory requirement of radio communication in U-LTE and the second to enhance their co-existence with Wi-Fi/IoT users in a non-interference style by reducing the back-off rate of Wi-Fi. The importance of spectrum utilization by the incumbent users of unlicensed band for the upcoming Internet of Things communications is also a key consideration in this work. The recently evolved intelligent technology viz. Cognitive radio (CR) is applied in the proposed system model to meet the objectives. A ground research is done in a simulation environment of LTE signals and 5 GHz band to evaluate the back-off rate of Wi-Fi. A comparative performance analysis between proposed and existing systems are also done and presented in this paper.

Coexistence of LTE-LAA and Wi-Fi on 5 GHz With Corresponding Deployment Scenarios: A Survey

Long term evolution (LTE) carrier aggregation with 5 GHz unlicensed national informational infrastructure band has been pointed out by the industry as a good solution to handle the rapidly increasing amounts of data traffic. To provide fair coexistence of LTE-licensed assisted access (LTE-LAA) and Wi-Fi on 5 GHz, several coexistence mechanisms have already been proposed. This paper provides a comprehensive survey of the coexistence of LTE-LAA and Wi-Fi on 5 GHz with corresponding deployment scenarios. We first analyze coexistence-related features of those two technologies, including motivation, LTE carrier aggregation with unlicensed band, LTE and Wi-Fi medium access control protocols comparison, coexistence challenges and enablers, performance difference between LTE-LAA and Wi-Fi, as well as co-channel interference. Second, we further extensively discuss current considerations about the coexistence of LTE-LAA and Wi-Fi. Third, influential factors for the classification of small cell scenarios, as well as four representative scenarios are investigated in detail. Then we explore a relatively smooth technical route for solving coexistence-related problems, which practically takes features of a specific scenario as the base for designing deployment mode of LTE-LAA and/or Wi-Fi. A scenario-oriented decision making procedure for the coexistence issue and the analysis on an example deployment scenario, including design and performance evaluation metrics focusing on the concept of the scenario-oriented coexistence are presented. We finally forecast further research trends on the basis of our conclusion.