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- Radio Resource Management of Heterogeneous Small Cell NetworksPublication . Paulo, Rui Filipe Rosa; Velez, Fernando José da SilvaWhile mobile communication users demand new high speed services with enhanced quality, there will always be a need to optimize cellular networks. This work explores the behavior of indoor and outdoor small cells while reducing the cell size to increase system capacity in both links. After justifying evolution of the use of small cells, the concepts of ultra-dense networks and heterogeneous networks toward 5G are then presented. In the initial part of this work, we have chosen a 3GPP 5x5 grid geometry for indoor scenarios. The average signal-to-interference-plus-noise ratio (SINR) has been studied for reuse pattern two and two types of deployment topologies, one with 25 HeNBs and another with 4 HeNBs. We have also addressed the exponential effective SINR mapping (EESM) by extending the study for topologies with 5 and 6 HeNBs. Based on an improved version of LTE-Sim, network performance has been evaluated in terms of the goodput, packet loss ratio (PLR), delay, and the maximum number of supported users. We have evaluated the performance by considering 4, 5, 6 and 25 HeNBs. Results complied with the 3GPP recommendations for PLR and delay. One observed that system capacity is higher for topologies with 25 HeNBs, followed by topologies with 6 HeNBs and 4 HeNBS, and then the indoor deployments with 5 HeNBs. Different packet schedulers have been considered. Results have shown that, with the considered applications and schedulers, it is possible to reduce the transmitter power of HeNBs without compromising the small cell network performance. In the final part of the work an urban micro line-of-sight cell scenario has been studied by comparing the 2.6 GHz, 3.5 GHz, and 5.62 GHz frequency bands while considering the ITU-R M.2135-1 dual slope path loss model (DS-PLM) in the system level simulations. Results have been obtained for different values of the cell radius. System capacity has been determined by considering the 3GPP quality target of 2% for video applications. For all schedulers and frequency bands, for cell radius shorter than the breakpoint distance, the PLR increases when the cell radius decreases. [...]
- Performance Evaluation and Packet Scheduling in HeNB DeploymentsPublication . Paulo, Rui R.; Velez, Fernando; Piro, GiuseppeThe unsupervised and chaotic deployment of Home eNBs (HeNBs) is leading to high levels of interference. To understand the behaviour of the interference of these uncoordinated deployments is vital to reach significant capacity improvement and also to explore opportunities to save energy. This paper considers high and middle interference level scenarios, with a maximum of four users per cell. HeNBs indoor deployed is considered within building. We theoretically analyse the traffic performance of this scenario through the study of the Signal-to-Interference-plus-Noise-Ratio (SINR). Through the use of the LTE-Sim simulator one obtains the quality indicators for two flows that are being utilised by the users. Video and best effort are studied, while varying the transmitter power and the areas of the apartments. The achieved SINR is higher (around 10 dBm) when the area of the cells is smaller. The variation of the transmitter power of the HeNBs does not present any significant impact. Noticeable throughout the simulations is observed that is possible to operate the system without setting the transmitter power of HeNBs to the maximum value at both interference levels. Simulation results also show that with the considered flows is possible to serve the maximum number of four users per HeNB with high quality. This statement is confirmed by the maximum achieved Packet Loss Ratio for video with a value of value of 1.6 %, which is lower than the maximum of 2 % indicated by the 3GPP. Taking into account the obtained results it is possible to promote a reduction in energy consumption of the HeNBs without penalizing the service quality.
- Influence of a Few More Channels for Voice Support in B3G Multi-Service Traffic in the Presence of MobilityPublication . Paulo, Rui R.; Velez, Fernando J.; Rodrigues, AntónioThe analysis of the impact of voice-over-IP into HSPA and LTE multi-service traffic is a challenge. The validation of a Bernoulli-Poisson-Pascal multi-service traffic model in the presence of mobility is explored for different values for the number of channels. A mixture of voice (VOI) and video telephony (VTE) is considered. In a previous work, a critical situation was assumed where the total number of channels was exactly the same as needed by four VTE sessions. However, when few extra channels are added there is a significant reduction on VTE on/off blocking probability. With this few extra resources, VOI can now be easily supported. Since it is supported on top of a system saturated with VTE sessions, Pbonoff decreases 4.6 times for VTE. Since the number of resources is not critical anymore, the range of values of the offered traffic for which the theoretical model agrees with simulation results becomes wider. There is no significative difference between the multi-service traffic results for the seven cell geometry and the roundabout (or ring) cellular topologies in the presence of mobility.
- Service Quality of the Urban Microcellular Scenario in the Sub-6 GHz Frequency BandsPublication . Paulo, Rui R.; Teixeira, Emanuel; Velez, Fernando J.This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GHz frequency bands in an urban micro-cellular outdoor setting. An updated version of LTE-Sim is considered to obtain the exponential effective signal-to-interference-plus-noise ratio in 4G while determining the modulation and coding scheme. System capacity is obtained by considering a video application at 3.1 Mb/s and the proportional fair (PF) scheduler while comparing 4G and 5G NR through system-level simulations (the 5G-air-simulator is considered for 5G NR). The modified largest weighted delay first (MLWDF) scheduler is compared with the PF, though only in 4G. Optimal system performance is reached both in 4G and 5G NR for cell radii longer than two times the breakpoint distance (or beyond), which are preferable compared to the shortest values for the cell radius. We have learned that the packet loss ratio (PLR) is higher for the cell radii, R, shorter than breakpoint distance, d′ BP. For d′BP ≤ R ≤ 1000 m, the PLR first decreases and then increases. For a target PLR < 2%, in 4G, the highest maximum average goodput is obtained with the M-LWDF scheduler (10-25% increase). This maximum occurs at the 2.6 GHz and 3.5 GHz frequency bands for 300 ≤ R ≤ 500 m, while at 5.62 GHz the highest goodput occurs for the longest Rs. With 5G NR and the PF, the maximum average goodput increases, in our simulations, from ≈ 14.1 (in 4G) to 26.1 Mb/s (20 MHz bandwidth).
- Cost Revenue Trade-off for the 5G NR Small Cell Network in the Sub-6 GHz Operating BandPublication . Khan, Bahram; Nidhi; Paulo, Rui R.; Mihovska, Albena D.; Velez, Fernando J.G Radio Access Network (RAN) dis-aggregation has opened up opportunities toward the 2nd phase of 5G. 3GPP and Telecom industries have defined backhaul, fronthaul, and mid-haul transport interfaces, as well as functional splits to incorporate network flexibility and openness. In this work, splits 6 and 7 (7.2) of 3GPP are addressed for implementing sub-6 GHz future wireless mobile communication networks. The 5G-air-simulator has been considered to simulate New Radio 2.6 GHz, 3.5 GHz, and 5.62 GHz frequency bands by using Video (VI) and Video plus Best-Effort (VI+BE) with the Proportional Fair (PF) packet scheduler. The split 6 is ideal for small cell deployment, while split 7, (mainly sub-split 7.2) requires high fiber capacity, which may increase the price of the fronthaul. In the simulations, we have considered a uniform user distribution and reuse pattern three. By assuming a set of cost parameters and a given price for the traffic, we have analysed the cost/revenue trade-off of outdoor pico/micro cells, while comparing the implementation of functional splits 6 and 7 with scenarios without splitting. It is shown that, for all bands, for cell radii up to 500-600 m the split 6 and 7 provides higher revenue and profit compared to the case without splitting (with slight advantage for split 7).
- Tele-Traffic Simulation for Mobile Communication Systems Beyond 3GPublication . Juarez Valero, Jesus M.; Paulo, Rui R.; Velez, Fernando J.European projects like Simulation of Enhanced UMTS Access and Core Network (IST-SEACORN) proposed a set of enhancements to UMTS. By considering the deployment scenarios and tele-traffic parameters from the Vehicular scenario of SEACORN, a simulator was produced to extract conclusions about blocking and handover failure probabilities. Simulation, which consider the burstiness of traffic, were performed for different cases, from single- to multi-service situations, and from absence to presence of mobility. Besides quality of service results in the air interface, including blocking and handover failure probabilities, the simulator allows for extracting conclusions about the validation of the Bernoulli/ Poisson/Pascal model for the computation of the ONOFF blocking probability, the ratio between the number of call rejected at the beginning of an ON period and the total number of bursts generated during a session. As the theoretical and the simulation results agree, the validation was achieved.
- Event-Based Simulation for Multi-rate Multi-service Traffic Validation in B3G SystemsPublication . Juarez, Jesus M.; Paulo, Rui R.; Velez, Fernando J.A multi-service traffic model is briefly presented, and its validation is achieved by using event-based simulation results which consider the burstiness of traffic. A simulator was produced to extract conclusions about blocking and handover failure probabilities in a multi-service bursty traffic context. Simulations, were performed for different cases, from single- to multi-service situations, and from absence to presence of mobility. Besides quality of service results in the air interface, including blocking and handover failure probabilities, the simulator allows for extracting conclusions about the validation of the Bernoulli-Poisson-Pascal model for the computation of the on/off blocking probability, the ratio between the number of call rejected at the beginning of an on period and the total number of bursts generated during a session. In the single-service case, the theoretical and the experimental values of on/off blocking probability are close to each other, and there is an almost perfect concordance between theoretical and simulation values when the average sojourn time in cells is equal to the average holding time. In the multi-service case, the behaviour is not exactly the same but a coherent behaviour is achieved for an average traffic per user up to 0.10 Erl.
- An Extensive Study on the Performance Evaluation and Scheduling of HeNBsPublication . Paulo, Rui R.; Velez, Fernando J.Since the dawn of mobile communication systems, reducing the cell size has been one option to increase the signal-to-interference-plus-noise ratio (SINR) in both links. The impact of this reduction can be perfectly understood by considering Shannon’s law. This work studies in detail the performance of Home eNBs (HeNBs), nodes with a smaller coverage area. After a detailed theoretical study of the SINR, a simulation approach is used to extract performance results in small cell indoor scenarios. Results corresponding to the goodput, delay and packet loss ratio are analyzed. Based on an improved version of LTE-Sim, the proportional fair, frame level scheduler (FLS) and exponential rule are tested in an indoor environment. With the saturation conditions taken into consideration, the FLS performs better than the other schedulers. This work shows that with the considered applications, it is possible to achieve a reduction in the transmitter power of HeNBs without compromising the small cell network performance.
- Impact of the Two-Slope Path Loss Model in the Service Quality of 4G and 5G Small CellsPublication . Paulo, Rui R.; Velez, Fernando J.Together with cell-free networks, small cells enable ultra-dense networks in 5G. Although small cell networks will be part of heterogeneous networks, the comparison of service quality of urban micro (UMi) small cells between 4G and 5G second phase scenarios is still of great relevance. Usage of video (VID), is considered. Quality of service (QoS) is determined by considering a packet loss ratio (PLR) lower than 2%, for different sub-6 GHz frequency bands. The aim is to compare the system capacity between 4G and 5G enhanced mobile broadband in different bands. ITU defined two UMi cell scenarios for urban micro cells that consider two-slope (TS) path loss models (PLMs). In this work, we have included TS-PLMs into the LTESim (4G) and 5G-air-simulator. The service quality and system performance bands have then been evaluated. Results shows that it is possible to support more user terminals (UTs) with 5G (up to 26 UTs) than with 4G (10 UTs only). When PLR<2%, the average delay decreases and the average goodput increases when 5G is considered. The maximum average goodput also increases with 5G.
- Design of Coordinated HeNB DeploymentsPublication . Paulo, Rui; Velez, Fernando; Piro, GiuseppeUncoordinated deployment of HeNBs has been widely considered, in the research community. However, due to economic or physical constraints, a coordinated deployment of HeNBs can also be considered. This work studies a selected examples of HeNB deployment. We consider the deployment of four Enterprise HeNB which serve up to 8 simultaneous users, in a building, with a geometry of 5x5 apartments. From the theoretical study on the average SINR, we have learned that the smaller the apartment areas are the higher the values for the average SINR are. The performance evolution of the system focuses on the values obtained for the average goodput, Packet Loss Ratio (PLR) and delay for the Proportional Fair, Frame Level Scheduler (FLS) and Exponential Rule (EXPRule) schedulers, with users using a video and a best effort flows at the same time. For the video flows the maximum average goodput was obtained with the FLS scheduler, but when the PLR is taken into account the EXPRule present a slight advantage. In the case of the BE flows, the EXPRule present the best performance. But the main lesson learned is that it is possible to operate a coordinated HeNB deployments without setting the transmitter power of the HeNBs to the maximum value, which can be a step to achieve a greener system.