TD-LTE network indoor offloading study in a realistic metropolitan scenario

In the wireless broadband network, most traffic are generated from indoor, and the indoor coverage is identified as the major bottleneck especially in dense urban environment with high-rising buildings. In this paper, the TD-LTE network downlink performance of indoor is studied with various deployment options, including outdoor Macro and Micro cell, indoor Femto cell and their combinations in a realistic large-scale dense urban scenario. For accurate modeling, the real three-dimensional (3D) city map of the investigated area is employed. A 3D ray-tracing tool is used to estimate the propagation occurring between outdoor sites and buildings. A semi-empirical building penetration extension is proposed to derive indoor predictions for each floor based on outdoor predictions at ground-level combined with a height gain model. The traffic offloading features of Micro and Femto cell are evaluated through system simulations.

To bring fifth generation (5G) mobile communication capabilities to indoor users, small cells and distributed antenna systems are two promising technologies being considered. This paper investigates and compares the performance of indoor deployed small cell base station (SBS) and indoor distributed antenna systems (DAS) in an isolated multi-storey building. Each floor of the building is equipped with either an indoor SBS or an indoor DAS where geographically distributed remote radio heads (RRHs) are connected to a central unit (CU), and frequency reuse is employed among floors. Signal propagation characteristics within multi-storey buildings and the impact of inter floor interference on performance is analysed and compared for both systems. The effect of different reuse distances, pathloss exponents, penetration loss and co-channel interference on achievable rate is analysed over a wide range of potential mobile equipment (ME) locations

As small cell solutions for efficient in-building wireless deployment, the distributed antenna system (DAS) and Femtocells constitute two major options. In this work, we study the Total Cost of Ownership (TCO) in combination with system performance in order to reach technology-economical conclusions regarding of these deployment options. Our aim is to identify the most cost economical solution for indoor wireless deployment which meets the indoor capacity need and provides ubiquitous indoor coverage. In the analysis we focus on LTE enhancement in the enterprise buildings. We discuss the unique cost features of DAS and Femto systems and highlight the importance of backhaul visibility in the cost analysis. For enterprise building solutions, we show the cost advantage of low-cost Femtocells over DAS in all scenarios regardless of coverage building size. We also suggest when DAS becomes more economical for large buildings with low data traffic need.

This paper analyzes the problem of optimum user association and sum rate maximization for software defined radio access networks (SD-RANs) with access node diversity for fifth generation (5G) wireless networks. We consider four complementary types of access nodes namely, a massive multiple- input multiple-output (MIMO) base station (BS), MIMO BSs, small cells (SCs), and indoor and outdoor distributed antenna systems (DAS). The SDRAN user association problem is solved through a novel three-stage optimization scheme called the place coverage (TPC). TPC divides the user equipment (UEs) into two sets of indoor and outdoor UEs. Initially, TPC associates indoor UEs with the indoor DAS access nodes. Next, outdoor UEs are associated with the outdoor DAS access nodes, SCs, MIMO BSs, and the massive MIMO BS. Finally, the remaining resources of indoor and outdoor access nodes are used to serve the UEs that have not been served. The scope of TPC is multifold. First, TPC reflects the closest model to a real-world diverse 5G network. Secondly, servicing the indoor UEs with iDAS antennas results in lower power load per user for the access network resulting in better coverage, quality, and data speed. Thirdly, TPC provides reduced radiation levels for indoor UEs. Numerical results show that TPC provides significant sum rate and fairness gains over the received signals strength (RSS) based association schemes [1]. Moreover, TPC provides comparable performance levels as the optimum association scheme based on exhaustive search while bringing significant complexity reduction.

In this paper, a distributed antenna system (DAS) is investigated for indoor high data rate wireless transmission in high buildings. In the proposed indoor DAS, radio transmission/ reception within several neighbouring floors is controlled by one central unit (CU) by exploiting the whole system bandwidth. However, the frequency channels can be reused among the CUs which results in co-channel interference. The capacity of the system is analyzed considering direct propagation inside the building and reflection from a nearby building. The impact of several system parameters, such as the position of the user on the floor, the number of remote antenna units (RAUs), the shape of the floor and the position of the RAUs on the performance is discussed.

SummaryThis paper presents two different configurations of ±45° dual‐wideband dual‐polarized (DWDP) antennas. The antenna comprises eight end‐loaded broadband dipoles grouped into two sets based on the bands of operation. The high‐frequency dipoles are strategically placed within the low‐frequency ones to form the elementary unit. Further optimization has been performed on the elementary unit in terms of the radiator placement to suppress sidelobe levels for array formation. Both configurations are meticulously fabricated using an all‐metal structure, demonstrating durability and the simplicity of fabrication. The antenna designs achieve ±45° polarization, high gain, satisfactory cross‐polarization discrimination (XPD), and wide impedance bandwidth covering 0.67–1.04 GHz and 1.54–3 GHz bands. Despite the nested configuration, mutual coupling is well within acceptable limits. Formation of the array based on the optimum elementary unit has been investigated by simulation, revealing reasonable gain enhancement and low sidelobe levels across all bands. This comprehensive approach yields a robust, high‐performing antenna configuration suitable for indoor distributed antenna system (IDAS) applications.

Ultra-dense and Distributed Antenna Systems (DAS) technology consist fundamental means for achieving the data rates and round-trip times promised by future mobile networks, because they promise to assure excellent indoor coverage and offer the potential to meet the target key performance indicators at a lower cost. In this paper, we study the techno-economic aspects of ultra-dense and DAS deployments. Apart from the presentation of their architectures and advantages, we present a techno-economic modeling of these deployment types. The defined models are used for the investigation of the upper technologies from an economic perspective and therefore, they provide an insight in the future financial and price aspects of these technologies by consisting a useful tool for the definition of financing and pricing policies towards an economically viable ultra-dense femtocell-based or DAS deployment. Finally, it is confirmed that the Total Cost of Ownership (TCO) is lower for the femtocells compared to the DAS.

This study investigates the joint power allocation and energy cooperation problem in a multiuser downlink distributed antenna system with hybrid energy supply. The authors focus on the energy efficiency (EE) maximization problem for three different types of precoding, zero‐forcing (ZF), general beamforming method and conjugate‐beamforming. For ZF precoding, they apply fractional programming and reform the optimization problem to a convex one. An iterative algorithm to deal with the fractional objective function is presented. Whereas the problem is non‐convex for general beamforming with user interference, they take maximum ratio transmission as an example and adopt a set of transformation and approximation based on the difference of convex (DC) programming. Furthermore, for conjugate‐beamforming, they first transform the quadratic signal to interference plus noise power ratio into a trackable form and then DC programming is applied. A two‐loop algorithm for the general beamforming and conjugate‐beamforming is presented with fractional programming in the inner loop and DC programming in the outer loop. Simulations show that the proposed algorithm improved EE significantly and indicate that energy cooperation can contribute to a higher EE. It also reveals that ZF achieves better EE with small noise variance while conjugate beamforming in high noise circumstance.

The rapid integrations of wireless controls in mechatronics, the broadening applications of wireless radio communications in aviation, and the exponential increase in the growth of mobile phone users in the last decade have made it necessary to expand the capacity of GSM users and ultimately increase the system performance. It has also become imperative for service providers to ensure adequate coverage is provided for all mobile users in areas with poor or no service. Even though many solutions such as distributed antenna system, relays, macrocells, and picocells were developed but they could not proffer the needed solution to indoor users. In this perspective, researchers were of the opinion that femtocells have a gifted technology to enhance indoor coverage because of properties such as short power, short coverage area, reduced distance between device and user and being a plug and play device. It was however discovered that research findings on large deployment of femtocells does not corroborate when a handful is deployed. This study therefore examines the influence of femtocells network on a small size indoor environment using ITU-R and WINNER II path loss models. To accomplish this, femtocells were modeled in six apartments of a building and parameters such as path loss, received power and signal to interference plus noise ratio were determined to ascertain the performance of a particular femtocell under the influence of co-tier interference. Results show that the ITU-R model was found to experience lower path losses which produced higher received powers than WINNER II (-57.0445dBm on the average).

Indoor spaces have already been accounted for a significant proportion of people's lives, and with the advent of the fifth-generation mobile communication technology (5G) era and the rise of the Internet of Things (IoT), the demand for indoor localization is further increasing. Current solutions for indoor positioning, such as Bluetooth, Wi-Fi, ultra-wideband (UWB), and pseudo-satellite technologies, have faced issues in terms of cost, accuracy, and scalability during the promotion and application process. In this regard, distributed antenna systems (DAS) have an absolute advantage in terms of indoor coverage for communication, which shows enormous potential for fusion with current indoor positioning technologies. This paper proposed a universal one-dimensional localization algorithm fusing UWB technology with the indoor DAS system, aimed at narrow indoor environments such as corridors and cable tunnels, which can achieve high-precision localization as evaluated in a real scenario of an indoor corridor in the Beijing University of Posts and Telecommunications (BUPT). Additionally, our algorithm requires only two anchors, effectively reducing positioning costs while improving accuracy. The results indicate that this localization technique effectively meets the requirements defined for indoor scenarios in 3GPP 38.855, with an error of decimeter level.

In this paper, simulation of two distinct kinds of metamaterial (MTM) antennas are proposed for fifth generation (5G) indoor distributed antenna systems (IDAS). Both antennas operate in the sub-6 GHz 5G band, i.e., 3.5 GHz and to analyze various factors like gain, directivity, return loss, radiation intensity for the frequency of 3.5 GHz. The simulation of this metamaterial antenna is carried out in ANSYS HFSS v2021. Results like return loss, radiation pattern, 3D polar plot, side lobe level, beamwidth, radiated power, accepted power have been obtained using HFSS v2021. This research on metamaterial gives a great view on how it can be designed and used at 3.5GHz frequency has a measured gain/bandwidth characteristic of 100 MHz/2.6 dBi and 700 MHz/2.3 dBi, respectively. The main advantage of this antenna is it can be used as both transmitting and receiving antenna. Key Words: Metamaterial, CSRR, return loss, triangular CSRR

The multi-application antenna is proposed for Bluetooth, Wi-Fi and Wi-max. The design is used for three different frequencies 2.45, 5 and 7 GHz. As a substrate material RT_Duroid 6006 is used. Antenna is designed by placing two slots in rectangular patch, so three dipoles are obtained. The simulation is done for this antenna by changing the length and width of three dipoles. The results shows that rectangular patch antenna with two slots offers return loss ≤10 dB with the input feed 50 Ω. The proposed antenna can be used in indoor distributed antenna systems, such as Bluetooth, Wi-Fi and Wi-max. This patch antenna was designed and simulated by ADS software. ADS supports of the design process—Engineer can characterize schematic capture, frequency and time-domain simulation, layout, and electromagnetic field simulation, allow engineer to characterize and RF design with common tool.

This study investigates the natural cross ventilation performance of a high-rise building surrounded by lower-level building blocks with varying roof angles and urban densities, using Computational Fluid Dynamics (CFD). The high-rise building model comprises three stacked building blocks, each designed with inlet and outlet openings, and is evaluated with surrounding buildings having roof angles of 0°, 15°, and −15°. Each building block is 16m in full-scale. The surrounding buildings are arranged according to three planar area ratios (PAR = 0.25, 0.4, and 0.6) to simulate low, medium, and high urban densities, respectively. Ventilation performance is assessed through Dimensionless Flow Rate (DFR), Air-Exchange Efficiency (AEE), pressure loss (ΔCp), and flow resistance (R) at each block of the high-rise building. Results reveal that roof angle and urban density significantly impact ventilation performance, particularly at the lower-level block (L1). For PAR = 0.25, the 0° roof angle configuration (case 1) yields the highest DFR of 0.1915 and AEE of 48.63% in L1, while angled roof configurations reduce these metrics by up to 38%. Similarly, at PAR = 0.4, the −15° angle (Case 6) improves DFR by 11.5% and AEE by 8.63%, while the 15° angle (case 5) reduces DFR by 37% and AEE by 15%, indicating how roof angle can either enhance or impede ventilation. At PAR = 0.6, angled roofs generally enhance ventilation in L1, with the −15° configuration (case 9) increasing DFR by 31.9% and AEE by 13.8% compared to the 0° roof angle. Analysis of pressure loss (ΔCp) and flow resistance (R) shows that R is highest in L1 across all densities due to the sheltering effect of surrounding buildings, while ΔCp and R in upper levels (L2 and L3) remain largely consistent across cases. These findings underscore the critical role of surrounding roof shapes and urban density in optimizing natural ventilation. The results provide valuable insights for designing high-rise buildings in dense urban environments, enhancing ventilation performance, and reducing reliance on mechanical systems, thereby contributing to sustainable urban design.

Cell-Free (CF) massive multiple-input multiple-output (MIMO) system is a distributed antenna system, wherein a large number of access points wish to simultaneously communicate with a relatively small number of users. Similar to co-located massive MIMO system, pilot contamination and multi-user interference are two major impediments to CF massive MIMO network performance improvement. One can mitigate the detrimental effect of pilot contamination and multi-user interference through judicious resource allocation. In this work, we formulate and investigate the problem of frequency assignment for a CF massive MIMO. The formulated optimization problem is proven to be generally NP-hard. Local optima can be found by approaches such as the Lagrangian method that however, has considerably slow rates of convergence. To circumvent this issue, we propose an alternative solution being of two-folds. Firstly, we reformulate the problem as a grouping strategy which enables to attenuate the effect of intra-group multi-user interference. In the second fold, frequencies are assigned in a non-overlapping fashion to each scheduled group to palliate the effect of inter-group interference and pilot contamination. To further improve the performance of the proposed approach, power coefficients are allocated to the users via a sequential convex approximation (SCA)-based framework. The effectiveness of the proposed algorithms is then verified through extensive numerical simulations which demonstrate a non-negligible improvement in the performance of the studied scenario.

In this paper, we experimentally investigate the throughput of IEEE 802.11n 2×2 multiple-input-multiple-output (MIMO) signals in a radio-over-fiber-based distributed antenna system (DAS) with different fiber links. Both a MIMO-supported access point (AP) and a spatial-diversity-supported AP were separately employed in the experiments. Throughput measurements were carried out with wireless users at different locations in a typical office environment. The results indicate that MIMO signals can maintain high throughput when the fiber length difference between the two remote antenna units (RAUs) is under 100 m and falls quickly when the length difference is greater. For the spatial diversity signals, high throughput can be maintained even when the difference is 150m.