Long Term Evolution Spectrum Research Articles

Stochastic Geometry-Based Evaluation of Edge User QoS With Cooperative Allocation

Long Term Evolution (LTE) frequency bands are being considered for use in 5G due to their coverage advantage. However, LTE usage is expected to be non-negligible for a while, so the amount of spectrum resources for it should be carefully estimated. In this letter, we propose a criterion for evaluating the adequacy of LTE spectrum resources in terms of edge user Quality of Service (QoS). For resource allocation to the edge user, we consider cooperative schemes that reflects the joint resource utilization of the associated and neighbor base stations. Based on stochastic geometry model, we derive semi-closed expressions of lower and upper bounds for the ergodic spectral efficiency at the edge user and devise a QoS satisfaction evaluation method through the decision region determined from them. Numerical analysis validates our derivations and shows the effect of joint resource utilization and cooperative allocations on QoS satisfaction.

A new fair-efficient spectrum allocation scheme for the LTE and WiFi coexistence platform

Long-term evolution (LTE) carrier aggregation with the unlicensed WiFi spectrum band has been pointed out as a good solution to handle the rapidly increasing wireless data traffic amounts. With both LTE and WiFi networks, the investigation of their coexistence is a hot research topic of active interest, primarily driven by industry and academia. In this study, we investigate a new spectrum allocation scheme for the LTE/WiFi coexistence platform. To maximize the system throughput while guaranteeing a relative fairness between heterogeneous networks, we adopt the cooperative game paradigm to design our novel scheme. According to the basic ideas of Proportional Nash bargaining solution (PNBS) and Zhang’s group bargaining solution (ZGBS), we can leverage a mutual consensus to provide a fair-efficient solution for the LTE/WiFi spectrum sharing problem. Based on the online interactive bargaining approach, network agents work together to effectively share the LTE and WiFi spectrum resources. Under dynamically changing network environments, it is an essential approach to find the relevant trade-off between conflicting requirements, i.e., fairness and efficiency. Validated by simulation results, our proposed scheme can provide important insights into the LTE/WiFi system operations. Finally, we forecast further research trends on the basis of our conclusion.

5G Campus Networks: A First Measurement Study

A 5G campus network is a 5G network for the users affiliated with the campus organization, e.g., an industrial campus, covering a prescribed geographical area. A 5G campus network can operate as a so-called 5G non-standalone (NSA) network (which requires 4G Long-Term Evolution (LTE) spectrum access) or as a 5G standalone (SA) network (without 4G LTE spectrum access). 5G campus networks are envisioned to enable new use cases, which require cyclic delay-sensitive industrial communication, such as robot control. We design a rigorous testbed for measuring the one-way packet delays between a 5G end device via a radio access network (RAN) to a packet core with sub-microsecond precision as well as for measuring the packet core delay with nanosecond precision. With our testbed design, we conduct detailed measurements of the one-way download (downstream, i.e., core to end device) as well as one-way upload (upstream, i.e., end device to core) packet delays and losses for both 5G SA and 5G NSA hardware and network operation. We also measure the corresponding 5G SA and 5G NSA packet core processing delays for download and upload. We find that typically 95% of the SA download packet delays are in the range from 4–10 ms, indicating a fairly wide spread of the packet delays. Also, existing packet core implementations regularly incur packet processing latencies up to 0.4 ms, with outliers above one millisecond. Our measurement results inform the further development and refinement of 5G SA and 5G NSA campus networks for industrial use cases. We make the measurement data traces publicly available as the IEEE DataPort 5G Campus Networks: Measurement Traces dataset (DOI 10.21227/xe3c-e968).

Four-Element Reconfigurable Coupled Loop MIMO Antenna Featuring LTE Full-Band Operation for Metallic-Rimmed Smartphone

This paper describes a low-profile $2\times 2$ multi-input multi-output (MIMO) antenna system that is fully functional over the entire long-term evolution (LTE) spectrum 699–960 MHz (lower frequency spectrum) and 1710–2690 MHz (higher frequency spectrum) that is applicable to real-life metallic smartphone platforms. The presented methodology entails utilizing the longitudinal edges of the ground plane amid an extremely narrow ground clearance of 2 mm. The metallic frame of the smartphone is utilized along with a stub network to devise a reconfigurable coupled loop antenna topology. The proposed $2\times 2$ MIMO antenna configuration is measured and confirmed to exhibit efficient envelope correlation coefficient (<0.5) and one of the highest radiation efficiencies to be reported in the literature across the entire LTE spectrum.

Reduced-Power Almost Black Subframe Based Pulse Radar Spectrum Sharing for LTE System

Cochannel pulse radar and long term evolution (LTE) deployments are considered by the FCC citizen broadband radio service (CBRS) and also 5G spectrum sharing. This paper proposes a radar spectrum sharing method based on LTE reduced-power almost blank subframe (RP-ABS) mechanism, which is used to mitigate interference to pulse radar while maintaining high LTE throughput. For LTE, payload bits are first packed into nonradar interfered time domain subframes (SFs), and then RP-ABS or even zero-power almost blank subframe (ABS) are adopted in the rest SFs. For pulse radar, target detection performance is guaranteed, thanks to the decreased interference caused by LTE RP-ABS power. We also formulate and solve an optimization problem for radar and RP-ABS-based LTE spectrum sharing, which consider tradeoffs between RP-ABS-based LTE performance (bit error rate and throughput) and radar detection probability concurrently. Using 3rd generation partnership project (3GPP) LTE sensitivity test as a benchmark, 28.83% throughput gain can be obtained for RP-ABS-based method. A hardware-in-the-loop testbed is also designed to prove spectrum sharing between RP-ABS-based LTE and radar viable.

Constrained Stochastic Game in Licensed-Assisted Access for Dynamic Contention Window Adaptation

Licensed-assisted access (LAA) allows operations on unlicensed spectrum for long term evolution. Enhanced listen-before-talk (LBT) scheme is required to improve LAA performance. In this letter, we investigate the LAA dynamic contention window adaptation scheme for individual and cooperative throughput optimization under buffer length constraint. We formulate a constrained stochastic game for this competitive scenario. The difference of buffer status is leveraged for collision alleviation and throughput improvement. A linear programming-based method is introduced to obtain the optimal policy, which is proved to be the constrained Nash equilibrium. Simulation results validate that the proposed scheme can achieve higher throughput than the existing LBT Cat-3 and Cat-4 schemes.

Anonymous Group Message Authentication Protocol for LTE‐based V2X Communications

AbstractCellular technologies, in particular the current long‐term evolution (LTE) and future 5G, are suitable for implementing vehicle‐to‐everything (V2X) services, due to the existing network infrastructure, device‐to‐device (D2D) communication capability, and guaranteed end‐to‐end delay. In LTE‐based V2X (LTE‐V), vehicle grouping plays an important role for improving LTE spectrum utilization and providing group‐oriented proximity‐based services (ProSe). However, the flourishing of LTE‐V group communications introduces unique privacy challenges. In this letter, the state‐of‐art standardization and research efforts are first reviewed, and their limitations are identified on achieving trajectory privacy for LTE‐V group communications. Then, an efficient and anonymous group message authentication protocol is proposed to support message batch verification. Security analysis and performance evaluation demonstrate the feasibility of the proposed protocol.

Bidding, pricing, and user subscription dynamics in asymmetric-valued Korean LTE spectrum auction: A hierarchical dynamic game approach

The tremendous increase in mobile data traffic coupled with fierce competition in wireless industry brings about spectrum scarcity and bandwidth fragmentation. This inevitably results in asymmetric-valued long term evolution (LTE) spectrum allocation that stems from different timing for twice improvement in capacity between competing operators, given spectrum allocations today. This motivates us to study the economic effects of asymmetric-valued LTE spectrum allocation. In this paper, we formulate the interactions between operators and users as a hierarchical dynamic game framework, where two spiteful operators simultaneously make spectrum acquisition decisions in the upper-level first-price sealed-bid auction game, and dynamic pricing decisions in the lower-level differential game, taking into account user subscription dynamics. Using backward induction, we derive the equilibrium of the entire game under mild conditions. Through analytical and numerical results, we verify our studies by comparing the latest result of LTE spectrum auction in South Korea, which serves as the benchmark of asymmetric-valued LTE spectrum auction designs.

Overview of LTE Spectrum Sharing Technologies

Long-Term Evolution (LTE) communication systems feature advanced frequency reuse and interference coordination techniques providing faster and more secured mobile services. However, the network capacity in licensed spectrum is still behind market demands. Dynamic spectrum access or spectrum sharing in other frequently vacant or unlicensed frequency bands is considered an effective means to boost system throughput. Different from operations in licensed spectrum with exclusive access, LTE deployment needs to take into account the distinct regulations on channel access to each shared frequency band, in order to avoid interference to incumbent users, and to maintain fair play with peer operators in heterogeneous networks. This paper presents an overview on LTE spectrum sharing technologies on three popular spectrums, including the TV white-space channels, the frequently unused service-dedicated 3.5-GHz citizens broadband radio service spectrums, and the 5-GHz unlicensed bands. Existing spectrum usage in these frequency bands is analyzed, and the proposed methodologies on compliant operations are discussed for the reference of potential solutions to more efficient spectrum sharing mechanisms in the next generation mobile networks.

Power Boosting and Compensation During OTA Testing of a Real 4G LTE Base Station in Reverberation Chamber

A fully operational 4G long-term evolution (LTE) base station is tested in a reverberation chamber to analyze its performance in the presence of a multipath environment, typical of wireless and vehicular communications. Transmission quality parameters are measured ranging from the empty chamber situation (very rich multipath channel) to a very high loading condition to mitigate multipath. In that way, both outdoor and indoor propagation are accounted for. A large attenuation is inserted between the transmitter and the antenna to reduce the signal received by the user to real-life values encountered in both outdoor and indoor environments. In these scenarios, operators may choose to transmit a constant power spectral density throughout all LTE spectrum, or to increase the energy of control channels at the expense of data channels in order to enforce transmission and provide better quality to the user, especially in poor radio conditions. This is called “power boosting,” and its effect is analyzed in this paper.