LTE Networks: Benchmarks, Prospects and Deployment Limitation

High speed packet access (HSPA) technology is a great achievement in mobile broadband but there is still a need to improve service delivery in order to meet the ever increasing demand for mobile broadband services. Long Term Evolution (LTE) is a 4G Network launched by the 3GPP (Third Generation Partnership project) that provides higher data rate for subscribers at the same time reducing the cost per bit for service providers and much higher overall capacity to deliver more throughputs and reduced latency. This paper provides a technological overview of the benchmarks, prospects and deployment limitation of LTE Network

Measurement and Optimization of LTE Performance

4G Long Term Evolution (LTE) mobile system is the fourth generation communication system adopted worldwide to provide high-speed data connections and high-quality voice calls. Given the recent deployment by mobile service providers, unlike GSM and UMTS, LTE can be still considered to be in its early stages and therefore many topics still raise great interest among the international scientific research community: network performance assessment, network optimization, selective scheduling, interference management and coexistence with other communication systems in the unlicensed band, methods to evaluate human exposure to electromagnetic radiation are, as a matter of fact, still open issues. In this work techniques adopted to increase LTE radio performances are investigated. One of the most wide-spread solutions proposed by the standard is to implement MIMO techniques and within a few years, to overcome the scarcity of spectrum, LTE network operators will offload data traffic by accessing the unlicensed 5 GHz frequency. Our Research deals with an evaluation of 3GPP standard in a real test best scenario to evaluate network behavior and performance

LTE-verkon suorituskyvyn parantaminen CDMA2000:sta LTE:hen tehdyn muutoksen jälkeen

CDMA2000 technology has been widely used on 450 MHz band. Recently the equipment availability and improved performance offered by LTE has started driving the operators to migrate their networks from CDMA2000 to LTE. The migration may cause the network performance to be in suboptimal state. This thesis presents four methods to positively influence LTE network performance after CDMA2000 to LTE migration, especially on 450 MHz band. Furthermore, three of the four presented methods are evaluated in a live network. The measured three methods were cyclic prefix length, handover parameter optimization and uplink coordinated multipoint (CoMP) transmission. The objective was to determine the effectiveness of each method. The research methods included field measurements and network KPI collection. The results show that normal cyclic prefix length is enough for LTE450 although the cell radius may be up to 50km. Only special cases exist where cyclic prefix should be extended. Operators should consider solving such problems individually instead of widely implementing extended cyclic prefix. Handover parameter optimization turned out to be an important point of attention after CDMA2000 to LTE migration. It was observed that if the handover parameters are not concerned, significant amount of unnecessary handovers may happen. It was evaluated that about 50% of the handovers in the network were unnecessary in the initial situation. By adjusting the handover parameter values 47,28 % of the handovers per user were removed and no negative effects were detected. Coordinated multipoint transmission has been widely discussed to be an effective way to improve LTE network performance, especially at the cell edges. Many challenges must be overcome before it can be applied to downlink. Also, implementing it to function between cells in different eNBs involve challenges. Thus, only intra-site uplink CoMP transmission was tested. The results show that the performance improvements were significant at the cell edges as theory predicted.CDMA2000 teknologiaa on laajalti käytetty 450 MHz:n taajuusalueella. Viime aikoina LTE:n tarjoamat halvemmat laitteistot ja parempi suorituskyky ovat kannustaneet operaattoreita muuttamaan verkkoaan CDMA2000:sta LTE:hen. Kyseinen muutos saattaa johtaa epäoptimaaliseen tilaan verkon suorituskyvyn kannalta. Tämä työ esittelee neljä menetelmää, joilla voidaan positiivisesti vaikuttaa LTE-verkon suorituskykyyn CDMA2000:ste LTE:hen tehdyn muutoksen jälkeen erityisesti 450 MHz:n taajuusalueella. Kolmea näistä menetelmistä arvioidaan tuotantoverkossa. Nämä kolme menetelmää ovat suojavälin pituus, solunvaihtoparametrien optimointi ja ylälinkin koordinoitu monipistetiedonsiirto. Tavoite oli määrittää kunkin menetelmän vaikutus. Tutkimusmenetelmiin kuului kenttämittaukset ja verkon suorituskykymittareiden analyysi. Tutkimustulosten perusteella voidaan sanoa, että normaali suojaväli on riittävän pitkä LTE450:lle vaikka solujen säde on jopa 50km. Vain erikoistapauksissa tarvitaan pidennettyä suojaväliä. Operaattoreiden tulisi ratkaista tällaiset tapaukset yksilöllisesti sen sijaan, että koko verkossa käytettäisiin pidennettyä suojaväliä. Solunvaihtoparametrien optimointi osoittautui tärkeäksi huomion aiheeksi CDMA2000:sta LTE:hen tehdyn muutoksen jälkeen. Turhia solunvaihtoja saattaa tapahtua merkittäviä määriä, mikäli parametreihin ei kiinnitetä huomiota. Lähtötilanteessa noin 50 % testiverkon solunvaihdoista arvioitiin olevan turhia. Solunvaihtoparametreja muuttamalla 47,28 % solunvaihdoista per käyttäjä saatiin poistettua ilman, että mitään haittavaikutuksia olisi huomattu. Koordinoidun monipistetiedonsiirron on laajalti sanottu olevan tehokas tapa parantaa LTE-verkon suorituskykyä, etenkin solujen reunoilla. Monia haasteita pitää ratkaista, enne kuin sitä voidaan käyttää alalinkin tiedonsiirtoon. Lisäksi sen käyttöön eri tukiasemien solujen välillä liittyy haasteita. Tästä syystä monipistetiedonsiirtoa voitiin testata vain ylälinkin suuntaan ja vain yhden tukiaseman välisten solujen kesken. Tulokset osoittivat, että suorituskyky parani merkittävästi solun reunalla

Characterization of a global 4G mobile communications network using the commercial aircraft network

The ever increasing demand for high data rates and mobility, at the same time with the lowest latency possible, comes as a motivation and inspiration for the writing of this dissertation. Besides terrestrial networks, another common way to communicate nowadays is via satellite networks; low Earth orbit satellites are the ones closer to the Earth, still, they are 800km away, requiring high energetic consumption. Routes used by commercial air traffic cover great part of the globe, with higher incidence in the most populated areas, namely North America, Europe and Eastern Asia. The main objective of this project is to prove that it would be possible to have a global coverage network or, at least, a network able to fulfil the needs of users located in the most populated regions, where air traffic is denser. Users would be able to communicate to any part of the world; the nearest aircraft gets the signal and, since they are organized as a mesh network, it travels from aircraft to aircraft until it reaches its final destination. LTE frequency bands have a great margin to operate without interfering with the frequencies used in aeronautical radio communication systems, as will be seen in Chapter 3. The work developed shows that the most favourable conditions regarding the maximum distances obtained to establish the communication will be to set up the proposed system using QPSK, a 1.4 MHz channel and transmission frequency should be 737 MHz. Thus, maximum attainable distance in rural scenario is 46.62 km.A constante procura por taxas de alto débito e mobilidade, aliado à menor latência possível, surgiram como motivação e inspiração para a escrita desta dissertação. Além das redes terrestres, outra forma comum de comunicar nos dias de hoje é recorrendo a redes de satélites; os satélites de baixa órbita são os que estão mais próximo da Terra, no entanto estão a 800km de distância, o que requer um elevado consumo energético. As rotas utilizadas pelos aviões comerciais cobrem grande parte do globo, com maior incidência nas zonas mais povoadas, nomeadamente América do Norte, Europa e Este da Asia. O maior objetivo deste projeto é provar que é possível haver uma rede de cobertura global ou, pelo menos, uma rede capaz de satisfazer as necessidades dos utilizadores localizados nas zonas mais povoadas onde o tráfego aéreo é mais frequente. Os utilizadores poderiam comunicar para qualquer parte do mundo; o avião mais próximo receberia o sinal e, como estes estão organizados numa rede mesh, o sinal viajaria de avião em avião, até chegar ao seu destino. As bandas de frequência usadas no LTE têm uma grande margem para operar sem interferir com as frequências utilizadas nas comunicações na aviação, como será visto no Capítulo 3. O A constante procura por taxas de alto débito e mobilidade, aliado à menor latência possível, surgiram como motivação e inspiração para a escrita desta dissertação. Além das redes terrestres, outra forma comum de comunicar nos dias de hoje é recorrendo a redes de satélites; os satélites de baixa órbita são os que estão mais próximo da Terra, no entanto estão a 800km de distância, o que requer um elevado consumo energético. As rotas utilizadas pelos aviões comerciais cobrem grande parte do globo, com maior incidência nas zonas mais povoadas, nomeadamente América do Norte, Europa e Este da Asia. O maior objetivo deste projeto é provar que é possível haver uma rede de cobertura global ou, pelo menos, uma rede capaz de satisfazer as necessidades dos utilizadores localizados nas zonas mais povoadas onde o tráfego aéreo é mais frequente. Os utilizadores poderiam comunicar para qualquer parte do mundo; o avião mais próximo receberia o sinal e, como estes estão organizados numa rede mesh, o sinal viajaria de avião em avião, até chegar ao seu destino. As bandas de frequência usadas no LTE têm uma grande margem para operar sem interferir com as frequências utilizadas nas comunicações na aviação, como será visto no Capítulo 3. O trabalho desenvolvido mostra-nos que as condições mais favoráveis, no que toca a distâncias máximas obtidas para estabelecer a comunicação, serão montar o sistema proposto utilizando QPSK, um canal de 1.4 MHz e cuja frequência de transmissão seja 737 MHz. Assim, consegue-se obter uma distância máxima de transmissão em ambiente rural de 46.62 km.rabalho desenvolvido mostra-nos que as condições mais favoráveis, no que toca a distâncias máximas obtidas para estabelecer a comunicação, serão montar o sistema proposto utilizando QPSK, um canal de 1.4 MHz e cuja frequência de transmissão seja 737 MHz. Assim, consegue-se obter uma distância máxima de transmissão em ambiente rural de 46.62 km

Lo standard LTE

Per il sempre crescente traffico dati la rete mobile, attualmente basata sul sistema UMTS, sta cominciando a dimostrare i suoi limiti. Per questo il 3GPP (third Generation Partnership Project) ha avviato la standardizzazione di un nuovo sistema di telecomunicazioni mobile, chiamato LTE (Long Term Evolution), che migliora il precedente ponendo ambiziosi traguardi in quanto a prestazioni. Attualmente il sistema è ancora in fase sperimentale e le prime applicazioni commerciali si avranno solo tra il 2010-2011. Questa tesi ha lo scopo di studiare le principali caratteristiche del livello fisico dell'LTE e valutarne le prestazioni offert

Link level performance evaluation and link abstraction for LTE/LTE-advanced downlink

Els objectius principals d'aquesta tesis són l'avaluació del rendiment a nivell d'enllaç i l'estudi de l'abstracció de l'enllaç pel LTE/LTE-Advanced DL. S’ha desenvolupat un simulador del nivell d'enllaç E-UTRA DL basat en la tecnologia MIMO-OFDM. Es simulen els errors d'estimació de canal amb un model d'error de soroll additiu Gaussià anomenat CEEM. El resultat d'aquest simulador serveix per avaluar el rendiment a nivell d'enllaç del LTE/LTE-Advanced DL en diferents entorns . La idea bàsica dels mètodes d'abstracció de l'enllaç és mapejar el vector de SNRs de les subportadores a un valor escalar, l'anomenada ESNR, la qual és usada per a predir la BLER. Proposem un innovador mètode d'abstracció de l'enllaç que pot predir la BLER amb bona precisió en esvaïments multicamí i que inclouen els efectes de les retransmissions HARQ. El mètode proposat es basa amb l'estimació de la informació mútua entre els bits transmesos i els LLRs rebuts.The main objectives of this dissertation are the evaluation of the link level performance and the study of link abstraction for LTE/LTE-Advanced DL. An E-UTRA DL link level simulator has been developed based on MIMO-OFDM technology. We simulate channel estimation errors by a Gaussian additive noise error model called CEEM. The result of this simulator serves to evaluate the MIMO-OFDM LTE/LTE-Advanced DL link level performance in different environments. The basic idea of link abstraction methods is to map the vector of the subcarrier SNRs to a single scalar, the ESNR, which is then used to predict the BLER. We propose a novel link abstraction method that can predict the BLER with good accuracy in multipath fading and including the effects of HARQ retransmissions. The proposed method is based on estimating the mutual information between the transmitted bits and the received LLRs.Postprint (published version

Design and Validation of a Software Defined Radio Testbed for DVB-T Transmission

This paper describes the design and validation of a Software Defined Radio (SDR) testbed, which can be used for Digital Television transmission using the Digital Video Broadcasting - Terrestrial (DVB-T) standard. In order to generate a DVB-T-compliant signal with low computational complexity, we design an SDR architecture that uses the C/C++ language and exploits multithreading and vectorized instructions. Then, we transmit the generated DVB-T signal in real time, using a common PC equipped with multicore central processing units (CPUs) and a commercially available SDR modem board. The proposed SDR architecture has been validated using fixed TV sets, and portable receivers. Our results show that the proposed SDR architecture for DVB-T transmission is a low-cost low-complexity solution that, in the worst case, only requires less than 22% of CPU load and less than 170 MB of memory usage, on a 3.0 GHz Core i7 processor. In addition, using the same SDR modem board, we design an off-line software receiver that also performs time synchronization and carrier frequency offset estimation and compensation

MBMS—IP Multicast/Broadcast in 3G Networks

In this article, the Multimedia Broadcast and Multicast Service (MBMS) as standardized in 3GPP is presented. With MBMS, multicast and broadcast capabilities are introduced into cellular networks. After an introduction into MBMS technology, MBMS radio bearer realizations are presented. Different MBMS bearer services like broadcast mode, enhanced broadcast mode and multicast mode are discussed. Streaming and download services over MBMS are presented and supported media codecs are listed. Service layer components as defined in Open Mobile Alliance (OMA) are introduced. For a Mobile TV use case capacity improvements achieved by MBMS are shown. Finally, evolution of MBMS as part of 3GPP standardization is presented