209 research outputs found

    Self-organised multi-objective network clustering for coordinated communications in future wireless networks

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    The fifth generation (5G) cellular system is being developed with a vision of 1000 times more capacity than the fourth generation (4G) systems to cope with ever increasing mobile data traffic. Interference mitigation plays an important role in improving the much needed overall capacity especially in highly interference-limited dense deployment scenarios envisioned for 5G. Coordinated multi-point (CoMP) is identified as a promising interference mitigation technique where multiple base stations (BS) can cooperate for joint transmission/reception by exchanging user/control data and perform joint signal processing to mitigate inter-cell interference and even exploit it as a useful signal. CoMP is already a key feature of long term evolution-advanced (LTE-A) and envisioned as an essential function for 5G. However, CoMP cannot be realized for the whole network due to its computational complexity, synchronization requirement between coordinating BSs and high backhaul capacity requirement. BSs need to be clustered into smaller groups and CoMP can be activated within these smaller clusters. This PhD thesis aims to investigate optimum dynamic CoMP clustering solutions in 5G and beyond wireless networks with massive small cell (SC) deployment. Truly self-organised CoMP clustering algorithms are investigated, aiming to improve much needed spectral efficiency and other network objectives especially load balancing in future wireless networks. Low complexity, scalable, stable and efficient CoMP clustering algorithms are designed to jointly optimize spectral efficiency, load balancing and limited backhaul availability. Firstly, we provide a self organizing, load aware, user-centric CoMP clustering algorithm in a control and data plane separation architecture (CDSA) proposed for 5G to maximize spectral efficiency and improve load balancing. We introduce a novel re-clustering algorithm for user equipment (UE) served by highly loaded cells and show that unsatisfied UEs due to high load can be significantly reduced with minimal impact on spectral efficiency. Clustering with load balancing algorithm exploits the capacity gain from increase in cluster size and also the traffic shift from highly loaded cells to lightly loaded neighbours. Secondly, we develop a novel, low complexity, stable, network-centric clustering model to jointly optimize load balancing and spectral efficiency objectives and tackle the complexity and scalability issues of user-centric clustering. We show that our clustering model provide high spectral efficiency in low-load scenario and better load distribution in high-load scenario resulting in lower number of unsatisfied users while keeping spectral efficiency at comparably high levels. Unsatisfied UEs due to high load are reduced by 68.5%68.5\% with our algorithm when compared to greedy clustering model. In this context, the unique contribution of this work that it is the first attempt to fill the gap in literature for multi-objective, network-centric CoMP clustering, jointly optimizing load balancing and spectral efficiency. Thirdly, we design a novel multi-objective CoMP clustering algorithm to include backhaul-load awareness and tackle one of the biggest challenges for the realization of CoMP in future networks i.e. the demand for high backhaul bandwidth and very low latency. We fill the gap in literature as the first attempt to design a clustering algorithm to jointly optimize backhaul/radio access load and spectral efficiency and analyze the trade-off between them. We employ 2 novel coalitional game theoretic clustering methods, 1-a novel merge/split/transfer coalitional game theoretic clustering algorithm to form backhaul and load aware BS clusters where spectral efficiency is still kept at high level, 2-a novel user transfer game model to move users between clusters to improve load balancing further. Stability and complexity analysis is provided and simulation results are presented to show the performance of the proposed method under different backhaul availability scenarios. We show that average system throughout is increased by 49.9% with our backhaul-load aware model in high load scenario when compared to a greedy model. Finally, we provide an operator's perspective on deployment of CoMP. Firstly, we present the main motivation and benefits of CoMP from an operator's viewpoint. Next, we present operational requirements for CoMP implementation and discuss practical considerations and challenges of such deployment. Possible solutions for these experienced challenges are reviewed. We then present initial results from a UL CoMP trial and discuss changes in key network performance indicators (KPI) during the trial. Additionally, we propose further improvements to the trialed CoMP scheme for better potential gains and give our perspective on how CoMP will fit into the future wireless networks

    Altruistic Transmit Beamforming for Cross-layer Interference Mitigation in Heterogeneous Networks

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    The emergence of heterogeneous networks, with low-power nodes operating under the umbrella of high-power macro cells, simplifies planning procedures for operators, but introduces the problem of cross-layer interference between the overlapping cells. An effective technique for combating interference is transmit beam-forming (TBF), a transmitter-side technique which utilizes partial knowledge of the channel and presence of multiple antennas at the transmitter to enhance the signal reception quality at a receiver. When applied to the base station associated with the receiver, TBF boosts the desired signal. On the other hand, when applied to the interfering base station, TBF reduces the effect of the interference signal. The former technique is commonly referred to as egoistic TBF, while the latter is known as altruistic TBF. In this thesis, we provide theoretical evaluation of the performance gains that altruistic TBF is able to offer to a heavily interfered user in a heterogeneous setting, when channel state information is conveyed from the receiver to the transmitter through a limited feedback channel. We show that the application of altruistic TBF to specifically defined clusters of interferers is able to drastically improve performance for the victim user. Furthermore, we prove the exact upper bound for the performance of the victim user, when only phase feedback is used for altruistic TBF and the source of interference is a single dominant interferer. Finally, we investigate and propose new techniques that can be applied to multi-antenna heterogeneous network scenarios for interference mitigation purposes

    Cooperative Transmission for Downlink Distributed Antenna in Time Division Duplex System

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    Multi-user distributed antenna system (MU-DAS) systems play the essential role in improving throughput performance in wireless communications. This improvement can be achieved by exploiting the spatial domain and without the need of additional power and bandwidth. In this thesis, three main issues which are of importance to the data rate transmission have been investigated. Firstly, user clustering in MU-DAS downlink systems has been considered, where this technique can be effciently used to reduce the complexity and cost caused by radio frequency chains, associated with antennas while keeping most of the diversity advantages of the system. The proposed user clustering algorithm which can select an optimal set of antennas for transmission. The capacity achieved by the proposed algorithm is almost same as the capacity of the optimum search method, with much lower complexity. Secondly, interference alignment in MU-DAS downlink systems has been studied. The inter-cluster interference is uncoordinated and limits the system performance. The inter-cluster interference should be eliminated or minimized carefully. The interference alignment is proposed to consolidate the strong inter-cluster interference into smaller dimensions of signal space at each user and use the remaining dimensions to transmit the desired signals without any interference. The performance of single cluster is better than the proposed algorithm due to the absence of intercluster interference in the single cluster. The numerical shows that the proposed algorithm is more suitable in multi-cell DAS environment due to the presence of inter-cell interference. Finally, the impact of different user mobility on TDD downlink MUDAS has been studied. The downlink data transmission in time division duplex (TDD) systems is optimized according to the channel state information (CSI) which is obtained at the uplink time slot. However, the actual channel at downlink time slot may be different from the estimated channel due to channel variation in mobility environment. Based on mobility state information (MSI), an autocorrelation based feedback interval adjustment technique is proposed. The proposed technique adjusts the CSI update interval and mitigates the performance degradation imposed by the user mobility and the transmission delay. Cooperative clusters are formed to maximize sum rate. In order to reduce the computational complexity, a channel gain based antenna selection and signal-to-interference plus noise ratio (SINR) based user clustering are developed. A downlink ergodic capacity is derived in single user clustering. The derived analytical expressions of the downlink ergodic capacity are verified by system simulations. Numerical results show that the proposed scheme can improved sum rate over the non cooperative system and no MSI knowledge. The proposed technique has good performance for a wide range of user speed and suitable for future wireless communications systems

    Interference management in wireless cellular networks

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    In wireless networks, there is an ever-increasing demand for higher system throughputs, along with growing expectation for all users to be available to multimedia and Internet services. This is especially difficult to maintain at the cell-edge. Therefore, a key challenge for future orthogonal frequency division multiple access (OFDMA)-based networks is inter-cell interference coordination (ICIC). With full frequency reuse, small inter-site distances (ISDs), and heterogeneous architectures, coping with co-channel interference (CCI) in such networks has become paramount. Further, the needs for more energy efficient, or “green,” technologies is growing. In this light, Uplink Interference Protection (ULIP), a technique to combat CCI via power reduction, is investigated. By reducing the transmit power on a subset of resource blocks (RBs), the uplink interference to neighbouring cells can be controlled. Utilisation of existing reference signals limits additional signalling. Furthermore, cell-edge performance can be significantly improved through a priority class scheduler, enhancing the throughput fairness of the system. Finally, analytic derivations reveal ULIP guarantees enhanced energy efficiency for all mobile stations (MSs), with the added benefit that overall system throughput gains are also achievable. Following this, a novel scheduler that enhances both network spectral and energy efficiency is proposed. In order to facilitate the application of Pareto optimal power control (POPC) in cellular networks, a simple feasibility condition based on path gains and signal-to-noise-plus- interference ratio (SINR) targets is derived. Power Control Scheduling (PCS) maximises the number of concurrently transmitting MSs and minimises their transmit powers. In addition, cell/link removal is extended to OFDMA operation. Subsequently, an SINR variation technique, Power SINR Scheduling (PSS), is employed in femto-cell networks where full bandwidth users prohibit orthogonal resource allocation. Extensive simulation results show substantial gains in system throughput and energy efficiency over conventional power control schemes. Finally, the evolution of future systems to heterogeneous networks (HetNets), and the consequently enhanced network management difficulties necessitate the need for a distributed and autonomous ICIC approach. Using a fuzzy logic system, locally available information is utilised to allocate time-frequency resources and transmit powers such that requested rates are satisfied. An empirical investigation indicates close-to-optimal system performance at significantly reduced complexity (and signalling). Additionally, base station (BS) reference signals are appropriated to provide autonomous cell association amongst multiple co-located BSs. Detailed analytical signal modelling of the femto-cell and macro/pico-cell layouts reveal high correlation to experimentally gathered statistics. Further, superior performance to benchmarks in terms of system throughput, energy efficiency, availability and fairness indicate enormous potential for future wireless networks

    マクロセルにオーバーレイするスモールセルのための層間干渉低減に関する研究

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    The huge number of mobile terminals in use and the radio frequency scarceness are the relevant issues for future wireless communications. Frequency sharing has been considered to solve the problem. Addressing the issues has led to a wide adoption of small cell networks particularly femtocells overlaid onto macrocell or small cells implemented with the support of distributed antenna systems (DASs). Small cell networks improve link quality and frequency reuse. Spectrum sharing improves the usage efficiency of the licensed spectrum. A macrocell underlaid with femtocells constitutes a typical two-tier network for improving spectral efficiency and indoor coverage in a spectrum sharing environment. Considering the end-user access control over the small cell base station (SBS), with shared usage of the macrocell’s spectrum, this dissertation contribution is an investigation of mitigation techniques of crosstier interference. Such cross-tier interference mitigation leads to possible implementation of multi-tier and heterogeneous networks. The above arguments underpin our work which is presented in the hereby dissertation. The contributions in this thesis are three-fold. Our first contribution is an interference cancellation scheme based on the transmitter symbols fed back to the femtocell base station (FBS) undergoing harmful cross-tier interference. We propose a cross-tier interference management between the FBS and the macrocell base station (MBS) in uplink communications. Our proposal uses the network infrastructure for interference cancellation at the FBS. Besides, we profit from terminal discovery to derive the interference level from the femtocell to the macrocell. Thus, additionally, we propose an interference avoidance method based on power control without cooperation from the MBS. In our second contribution, we dismiss the use of the MBS for symbol feedback due to delay issues. In a multi-tier cellular communication system, the interference from one tier to another, denoted as cross-tier interference, is a limiting factor for the system performance. In spectrum-sharing usage, we consider the uplink cross-tier interference management of heterogeneous networks using femtocells overlaid onto the macrocell. We propose a variation of the cellular architecture and introduce a novel femtocell clustering based on interference cancellation to enhance the sum rate capacity. Our proposal is to use a DAS as an interface to mitigate the cross-tier interference between the macrocell and femtocell tiers. In addition, the DAS can forward the recovered data to the macrocell base station (MBS); thus, the macrocell user can reduce its transmit power to reach a remote antenna unit (RAU) located closer than the MBS. By distributing the RAUs within the macrocell coverage, the proposed scheme can mitigate the cross-tier interference at different locations for several femtocell clusters. Finally, we address the issue of cross-tier interference mitigation in heterogeneous cognitive small cell networks comparing equal and unequal signal-to-noise ratio (SNR) branches in multi-input multi-output (MIMO) Alamouti scheme. Small cell networks enhance spectrum efficiency by handling the indoor traffic of mobile networks on a frequency-reuse operation. Because most of the current mobile traffic happens indoor, we introduce a prioritization shift by imposing a threshold on the outage generated by the outdoor mobile system to the indoor small cells. New closed-form expressions are derived to validate the proposed bit error rate (BER) function used in our optimization algorithm. We propose a joint transmit antenna selection and power allocation which minimizes the proposed BER function of the outdoor mobile terminal. The optimization is constrained by the outage at the small cell located near the cooperating transmit relays. Such constraint improves the initialization of the iterative algorithm compared to randomly choosing initial points. The proposed optimization yields a dynamic selection of the relays with power control pertaining to the outdoor mobile terminal performance.電気通信大学201

    Interference Management Techniques for Cellular Wireless Communication Systems

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    The growing demand for higher capacity wireless networks can be met by increasing the frequency bandwidth, spectral efficiency, and base station density. Flexible spectrum access, multiantenna, and multicarrier techniques are key enablers in satisfying the demand. In addition, automation of tasks related to network planning, optimization, interference management, and maintenance are needed in order to ensure cost-efficiency. Effective, dynamic, and automated interference management tailored for bursty and local data traffic plays a central role in the task. Adjacent channel interference (ACI) management is an enabler for flexible spectrum use and uncoordinated network deployments. In this thesis the impact of ACI in local area time division duplex (TDD) cellular systems is demonstrated. A method is proposed where the transmitters optimize their transmitted spectral shape on-line, such that constraints on ACI induced by power amplifier non-linearity are met. The proposed method increases the fairness among spectrum sharing transceivers when ACI is a limiting factor. A novel interference-aware scheduling technique is proposed and analyzed. The technique manages co-channel interference (CCI) in a decentralized fashion, relying on beacon messages sent by data receivers. It is demonstrated that the proposed technique is an enabler for fair spectrum sharing among operators, independent adaptation of uplink/downlink switching points in TDD networks, and it provides overall more fair and spectrally efficient wireless access. Especially, the technique is able to improve the cell-edge throughput tremendously. New services are emerging that generate local traffic among the users in addition to the data traffic between the users and the network. Such device-to-device (D2D) traffic is effectively served by direct transmissions. The thesis demonstrates the possibilities for allowing such direct D2D transmissions on a shared band together with the cellular communication. It is shown that interference management is needed in order to facilitate reliable and efficient shared band operation. For this purpose, three methods are proposed that provide interference aware power control, interference aware multiuser and multiband resource allocation, and interference avoiding spatial precoding. It is shown that enabling direct transmission itself provides most of the gains in system capacity, while the interference management schemes are more important in promoting fairness and reliability.Langattomien tietoliikenneverkkojen käyttö kasvaa erittäin nopeasti mobiilien internet-palvelujen ja älykkäiden päätelaitteiden suosion myötä. Järjestelmien tiedonsiirtokapasiteettiä voidaan lisätä kasvattamalla kaistanleveyttä, spektritehokkuutta ja tukiasemaverkon tiheyttä. Kehityksen mahdollistaa mm. joustava taajuuksien käyttö ja moniantenni- ja monikantoaaltotekniikat. Lisäksi radioverkkojen suunnitteluun, optimointiin, ylläpitoon ja interferenssinhallintaan liittyvien tehtävien automatisoinnilla voidaan pienentää verkko-operaattoreiden kustannuksia. Tässä hetkellisen ja paikallisen tietoliikenteen tehokas, dynaaminen ja automatisoitu interferenssinhallinta on keskeisessä asemassa. Viereisen kanavan interferenssin hallinta mahdollistaa osaltaan joustavan spektrinkäytön ja koordinoimattoman verkkojen asennuksen. Väitöskirjassa on analysoitu viereisen kanavan interferenssin vaikutusta aikajakoiseen dupleksilähetykseen perustuvien paikallisten radioverkkojen toimintaan. Lisäksi väitöskirjassa on kehitetty menetelmä, jolla voidaan hallita interferenssiä reaaliaikaisesti. Menetelmä maksimoi lähetetyn signaalin spektritehokkuuden siten, että tehovahvistimen epälineaarisuuden aiheuttama viereisen kanavan interferenssi on rajoitettu. Väitöskirjassa on kehitetty ja analysoitu uudenlainen interferenssitietoinen lähetysten ajoitustekniikka. Tekniikka hallitsee reaaliaikaisesti ja hajautetusti saman kanavan interferenssiä vastaanottimien lähettämien majakkasignaalien avulla. Esitetyt simulaatiot osoittavat, että tämä mahdollistaa operaattoreiden välisen taajuuskaistojen jaon, ja alas- ja yloslinkkien aikajaon joustavan säädön. Tämän lisäksi on mahdollista saavuttaa korkeampi yleinen spektritehokkuus. Erityisesti tiedonsiirtonopeus solujen reunoille kasvaa esitetyn tekniikan avulla huomattavasti. Uudenlaiset tietoliikennepalvelut lisäävät laitteidenvälisen paikallisen tietoliikenteen määrää. Spektrinkäytön kannalta tämä liikenne on tehokkainta lähettää suoraan laitteesta toiseen. Väitöskirjassa on tutkittu joustavaa spektrinkäyttöä suorien laitteidenvälisten lähetysten ja soluverkon välillä. Interferenssin hallinta takaa luotettavan ja tehokkaan spektrin yhteiskäytön. Tätä varten väitöskirjassa on kehitetty kolme menetelmää, jotka perustuvat tehonsäätöön, lähetysten ajoitukseen ja moniantennilähetykseen

    Cooperative Resource Allocation in Wireless Communication Networks

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    The concept of cooperation where two or more parties work together to pursue a common goal, is applicable in almost every aspect of today's life. For instance, in the upcoming car-to-car communications, the vehicles exchange information regarding their current status and potential threats on the road in order to avoid accidents. With the evolution of the wireless communication systems and the advent of new services and devices with more capabilities, the demand for higher data rates is ever increasing. In cellular networks, the achievable data rates of the users are limited by the inter-cell interference, which is caused by the simultaneous utilization of the time/frequency resources. Especially, the data rates of the users located at the vicinity of neighboring base stations is affected by the inter-cell interference. Hence, in this dissertation, cooperation in cellular communication downlink networks is investigated, where the base stations coordinate their operation in order to mitigate the impact of co-channel inter-cell interference. Thus, the constantly increasing user demand can be satisfied. Cooperative resource allocation schemes are derived, where practical conditions and side constraints regarding the available channel state information at the base stations are taken into account. Cooperation in the form of power control and joint time/frequency scheduling is mainly studied. In the former type of cooperation, the base stations dynamically adjust their own transmit powers to cause less inter-cell interference to the users connected to neighboring base stations. In the case of cooperative scheduling, the available time/frequency resources are jointly allocated by the base stations in order to trade off user throughput and inter-cell interference. The cooperative scheduling schemes apply two special cases of the power control approach, where the base stations either serve their connected users with maximum transmit power, or abstain from transmitting data, i.e., muting, in order to reduce the interference caused to users served by neighboring base stations. One major contribution of this work is the formulation of the cooperative resource allocation problems by considering the availability of channel state information at the transmitter in form of data rate measurement reports, which follows standard compliant procedures of current mobile networks such as LTE and LTE-Advanced. From a system perspective, two parameters are considered throughout this dissertation in order to derive the proposed cooperative schemes. These parameters are the cooperation architecture and the traffic model characterizing the demand of the connected users. In the case of the cooperation architecture, centralized and decentralized schemes are studied. In the former, a central controller performs the cooperative schemes based on global knowledge of the channel state information, and in the latter, the cooperative decisions are carried out independently per base station based on local information exchanged with adjacent base stations. It is expected that the centralized architecture provides the best performance, however, the gap with respect to the decentralized approaches reduces significantly under practical network assumptions, as demonstrated in this work based on numerical simulations. With respect to the traffic model, the user demand is characterized by full-buffer and non-full-buffer models. The first model is applied in order to assess the performance of the proposed cooperative schemes from a capacity enhancement perspective, where all users constantly demand as much data as possible. On the other hand, the non-full-buffer model represents a more practical network scenario with a dynamic utilization of the network resources. In the non-full-buffer model case, the proposed schemes are derived in order to improve the link adaptation procedures at the base stations serving users with bursty traffic. These link adaptation procedures, establish the transmission parameters used per serving link, e.g., the transmit power, the modulation and the coding schemes. Specifically, a cooperative power control scheme with closed-form solution is derived, where base stations dynamically control their own transmit powers to satisfy the data rate requirements of the users connected to neighboring base stations. Moreover, centralized and decentralized coordinated scheduling with muting is studied to improve the user throughput. For the centralized case, an integer linear problem formulation is proposed which is solved optimally by using commercial solvers. The optimal solution is used as a benchmark to evaluate heuristic algorithms. In the case of decentralized coordinated scheduling with muting, a heuristic approach is derived which requires a low number of messages exchanged between the base stations in order to coordinate the cooperation. Finally, an integer linear problem is formulated to improve the link adaptation procedures of networks with user demand characterized by bursty traffic. This improvement results in a reduction of the transmission error rates and an increase of the experienced data rates. With respect to non-cooperative approaches and state-of-the-art solutions, significant performance improvement of the achievable user throughput is obtained as the result of applying the proposed cooperative schemes, especially for the users experiencing severe inter-cell interference

    Optimization of 5G Second Phase Heterogeneous Radio Access Networks with Small Cells

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    Due to the exponential increase in high data-demanding applications and their services per coverage area, it is becoming challenging for the existing cellular network to handle the massive sum of users with their demands. It is conceded to network operators that the current wireless network may not be capable to shelter future traffic demands. To overcome the challenges the operators are taking interest in efficiently deploying the heterogeneous network. Currently, 5G is in the commercialization phase. Network evolution with addition of small cells will develop the existing wireless network with its enriched capabilities and innovative features. Presently, the 5G global standardization has introduced the 5G New Radio (NR) under the 3rd Generation Partnership Project (3GPP). It can support a wide range of frequency bands (<6 GHz to 100 GHz). For different trends and verticals, 5G NR encounters, functional splitting and its cost evaluation are well-thought-out. The aspects of network slicing to the assessment of the business opportunities and allied standardization endeavours are illustrated. The study explores the carrier aggregation (Pico cellular) technique for 4G to bring high spectral efficiency with the support of small cell massification while benefiting from statistical multiplexing gain. One has been able to obtain values for the goodput considering CA in LTE-Sim (4G), of 40 Mbps for a cell radius of 500 m and of 29 Mbps for a cell radius of 50 m, which is 3 times higher than without CA scenario (2.6 GHz plus 3.5 GHz frequency bands). Heterogeneous networks have been under investigation for many years. Heterogeneous network can improve users service quality and resource utilization compared to homogeneous networks. Quality of service can be enhanced by putting the small cells (Femtocells or Picocells) inside the Microcells or Macrocells coverage area. Deploying indoor Femtocells for 5G inside the Macro cellular network can reduce the network cost. Some service providers have started their solutions for indoor users but there are still many challenges to be addressed. The 5G air-simulator is updated to deploy indoor Femto-cell with proposed assumptions with uniform distribution. For all the possible combinations of apartments side length and transmitter power, the maximum number of supported numbers surpassed the number of users by more than two times compared to papers mentioned in the literature. Within outdoor environments, this study also proposed small cells optimization by putting the Pico cells within a Macro cell to obtain low latency and high data rate with the statistical multiplexing gain of the associated users. Results are presented 5G NR functional split six and split seven, for three frequency bands (2.6 GHz, 3.5GHz and 5.62 GHz). Based on the analysis for shorter radius values, the best is to select the 2.6 GHz to achieve lower PLR and to support a higher number of users, with better goodput, and higher profit (for cell radius u to 400 m). In 4G, with CA, from the analysis of the economic trade-off with Picocell, the Enhanced multi-band scheduler EMBS provide higher revenue, compared to those without CA. It is clearly shown that the profit of CA is more than 4 times than in the without CA scenario. This means that the slight increase in the cost of CA gives back more than 4-time profit relatively to the ”without” CA scenario.Devido ao aumento exponencial de aplicações/serviços de elevado débito por unidade de área, torna-se bastante exigente, para a rede celular existente, lidar com a enormes quantidades de utilizadores e seus requisitos. É reconhecido que as redes móveis e sem fios atuais podem não conseguir suportar a procura de tráfego junto dos operadores. Para responder a estes desafios, os operadores estão-se a interessar pelo desenvolvimento de redes heterogéneas eficientes. Atualmente, a 5G está na fase de comercialização. A evolução destas redes concretizar-se-á com a introdução de pequenas células com aptidões melhoradas e características inovadoras. No presente, os organismos de normalização da 5G globais introduziram os Novos Rádios (NR) 5G no contexto do 3rd Generation Partnership Project (3GPP). A 5G pode suportar uma gama alargada de bandas de frequência (<6 a 100 GHz). Abordam-se as divisões funcionais e avaliam-se os seus custos para as diferentes tendências e verticais dos NR 5G. Ilustram-se desde os aspetos de particionamento funcional da rede à avaliação das oportunidades de negócio, aliadas aos esforços de normalização. Exploram-se as técnicas de agregação de espetro (do inglês, CA) para pico células, em 4G, a disponibilização de eficiência espetral, com o suporte da massificação de pequenas células, e o ganho de multiplexagem estatística associado. Obtiveram-se valores do débito binário útil, considerando CA no LTE-Sim (4G), de 40 e 29 Mb/s para células de raios 500 e 50 m, respetivamente, três vezes superiores em relação ao caso sem CA (bandas de 2.6 mais 3.5 GHz). Nas redes heterogéneas, alvo de investigação há vários anos, a qualidade de serviço e a utilização de recursos podem ser melhoradas colocando pequenas células (femto- ou pico-células) dentro da área de cobertura de micro- ou macro-células). O desenvolvimento de pequenas células 5G dentro da rede com macro-células pode reduzir os custos da rede. Alguns prestadores de serviços iniciaram as suas soluções para ambientes de interior, mas ainda existem muitos desafios a ser ultrapassados. Atualizou-se o 5G air simulator para representar a implantação de femto-células de interior com os pressupostos propostos e distribuição espacial uniforme. Para todas as combinações possíveis do comprimento lado do apartamento, o número máximo de utilizadores suportado ultrapassou o número de utilizadores suportado (na literatura) em mais de duas vezes. Em ambientes de exterior, propuseram-se pico-células no interior de macro-células, de forma a obter atraso extremo-a-extremo reduzido e taxa de transmissão dados elevada, resultante do ganho de multiplexagem estatística associado. Apresentam-se resultados para as divisões funcionais seis e sete dos NR 5G, para 2.6 GHz, 3.5GHz e 5.62 GHz. Para raios das células curtos, a melhor solução será selecionar a banda dos 2.6 GHz para alcançar PLR (do inglês, PLR) reduzido e suportar um maior número de utilizadores, com débito binário útil e lucro mais elevados (para raios das células até 400 m). Em 4G, com CA, da análise do equilíbrio custos-proveitos com pico-células, o escalonamento multi-banda EMBS (do inglês, Enhanced Multi-band Scheduler) disponibiliza proveitos superiores em comparação com o caso sem CA. Mostra-se claramente que lucro com CA é mais de quatro vezes superior do que no cenário sem CA, o que significa que um aumento ligeiro no custo com CA resulta num aumento de 4-vezes no lucro relativamente ao cenário sem CA
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