SwePub - sökning: L773:1550 2252 OR L773:9781424...

Numrering	Referens	Omslagsbild	Hitta
1.	Bilstrup, Katrin, et al. (författare) Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication 2008 Ingår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall. - Piscataway, N.J. : IEEE Press. - 9781424417216 ; , s. 1-5 Konferensbidrag (refereegranskat)abstract In this paper the medium access control (MAC) method of the upcoming vehicular communication standard IEEE 802.11p has been simulated in a highway scenario with periodic broadcast of time-critical packets (so-called heartbeat messages) in a vehicle-to-vehicle situation. The 802.11p MAC method is based on carrier sense multiple access (CSMA) where nodes listen to the wireless channel before sending. If the channel is busy, the node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for time critical communications. The simulation results reveal that a specific node/vehicle is forced to drop over 80% of its heartbeat messages because no channel access was possible before the next message was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. This MAC method is already successfully applied in commercial surveillance applications for ships (AIS) and airplanes (VDL mode 4). Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad hoc vehicular networks.
2.	Nilsson, Dennis, 1980, et al. (författare) Efficient In-Vehicle Delayed Data Authentication Based on Compound Message Authentication Codes 2008 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424417223 Konferensbidrag (refereegranskat)abstract Modern vehicles contain an in-vehicle network consisting of a number of electronic control units (ECUs). These ECUs are responsible for most of the functionality in the vehicle, including vehicle control and maneuverability. To date, no security features exist in this network since it has been isolated. However, an upcoming trend among automobile manufacturers is to establish a wireless connection to the vehicle to provide remote diagnostics and software updates. As a consequence, the in-vehicle network is exposed to external communication, and a potential entry point for attackers is introduced. Messages sent on the in-vehicle network lack integrity protection and data authentication; thus, the network is vulnerable to injection and modification attacks. Due to the real-time constraints and the limited resources in the ECUs, achieving data authentication is a challenge. In this paper, we propose an efficient delayed data authentication using compound message authentication codes. A message authentication code is calculated on a compound of successive messages and sent together with the subsequent messages, resulting in a delayed authentication. This data authentication could be used to detect and possibly recover from injection and modification attacks in the in-vehicle network.
3.	Sternad, Mikael, et al. (författare) Resource allocation and control signaling in the WINNER flexible MAC concept 2008 Ingår i: 68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008. - 9781424417216 ; , s. 1553-1557, s. Art. no. 4657161- Konferensbidrag (refereegranskat)abstract The EU WINNER projects have studied OFDM-based packet data systems beyond 3G that use adaptivity on all time-scales to obtain high flexibility and performance. The adaptive transmission in both downlink and uplink is scheduled and controlled at base stations and relay nodes and requires frequent transmission of control information over the downlink. The use of scheduling, adaptive modulation and coding, with fine granularity in both time and space, could potentially result in unrealistic bandwidth demands for such downlink control signaling. The present paper describes how this problem has been handled within WINNER in two cases: Frequency-adaptive transmission, which allows individual link adaptation within time-frequency resource units and non-frequency adaptive transmission, which averages over the channel variations in the frequency domain. An important tool for limiting the associated control information is to broadcast only a small essential set of control data to all user terminals, using a safe but therefore bandwidth-demanding code rate. The remaining control information is multicast to groups of users with different signal to interference and noise ratios (SINRs). The modulation and code rates of these transmissions are adjusted to the SINRs of these groups. The over-all coded data rate of the control transmission can thereby be reduced to acceptable levels.
4.	Verendel, Vilhelm, 1980, et al. (författare) An Approach to using Honeypots in In-Vehicle Networks 2008 Ingår i: 68th Semi-Annual IEEE Vehicular Technology, VTC 2008-Fall, Conference; Calgary, AB; Canada; 21 September 2008 through 24 September 2008. - 1550-2252. - 9781424417223 Konferensbidrag (refereegranskat)abstract An emerging trend among automobile manufacturers is to introduce wireless technology in the vehicles. By allowing wireless communication, real-time information exchange between vehicles as well as between infrastructure and vehicles becomes a reality. This communication allows for road condition reporting, decision making, and remote diagnostics and firmware updates over-the-air, creating a complex critical infrastructure involving vehicles, road-side equipment, and firmware issuers. Allowing external parties wireless access to the vehicle creates a potential entry-point for cyber attacks. Since the safety of the driver depends on correct vehicle operation it is of utmost importance that the in-vehicle network is sufficiently protected against attacks. If we can learn the attackers' preferences, techniques, and weaknesses in existing systems, we can use this information to design security solutions for the in-vehicle network. In this paper, we present and discuss the use of honeypots as a means of collecting such attacker information. We show how to design a vehicle honeypot, how to gather data from attackers, and discuss how to process and analyze the gathered data. Furthermore, we provide a discussion where we highlight important issues related to using honeypots in vehicles.
5.	Alegria, Juan Vidal, et al. (författare) Decentralized equalizer construction for large intelligent surfaces 2019 Ingår i: 2019 IEEE 90th Vehicular Technology Conference, VTC 2019 Fall - Proceedings. - 1550-2252. - 9781728112206 ; 2019-September Konferensbidrag (refereegranskat)abstract In this paper we present fully decentralized methods for calculating an approximate zero- forzing (ZF) equalizer in a large intelligent surface (LIS). A LIS is intended for wireless communication and facilitates unprecedented MU- MIMO performance, far superior to that of Massive MIMO. Antenna modules in the grid connect to their neighbors to exchange messages of information needed for interference cancellation in a fully- decentralized fashion, making the system scalable. By a careful design of how the messages are routed, we show that the proposed method is able to cancel inter-user interference sufficiently well without any centralized coordination, opening the door for the realization of this type of structures.
6.	Almers, Peter, et al. (författare) Effect of random walk phase noise on MIMO measurements 2005 Ingår i: [Host publication title missing]. - 1550-2252. ; 61:1, s. 141-145 Konferensbidrag (refereegranskat)abstract In this paper we study the influence of phase noise from free-running local oscillators on SAGE signal parameter estimation. Phase noise is here modeled as a random-walk process. We present phase noise estimates from our LUND RUSK MIMO channel sounder, and draw conclusions on requirements on local oscillators' phase noise in terms of the Allan variance. We investigate an error propagation effect in SAGE, and finally, we present random-walk phase noise effect on channel capacity.
7.	Ang, Lay-Hong, et al. (författare) Modification of SOVA-based Algorithms for Efficient Hardware Implementation 2010 Ingår i: IEEE 71st Vehicular Technology Conference (VTC 2010-Spring), 2010. - 1550-2252. ; , s. 1-5 Konferensbidrag (refereegranskat)abstract In this paper, a modified soft-output Viterbi algorithm (SOVA) is presented to enable efficient hardware implementation. The forward-only processing of the SOVA has an inherent lower latency than forward-backward algorithms such as BCJR and its offspring, which are commonly used in iterative decoders. Thus, SOVA-based architectures require less parallelization and therefore hardware for the same data throughput. A simplification is proposed to the Battail rule ( BR) SOVA to approximate the concurrent path reliability values with the corresponding metric differences. This simplified BR-SOVA (SB-SOVA) performs close to max-log-MAP. Furthermore, a novel hybrid decoding architecture is proposed that combines the simplicity of the original Hagenauer rule and the performance-preserving properties of the SB-SOVA to trade implementation complexity for decoding performance. The hybrid approach is evaluated with practical link-level simulations of the downlink data channel in LTE Rel-8.
8.	Aronsson, Daniel, et al. (författare) Performance Evaluation of Memory-less and Kalman-based Channel Estimation for OFDMA 2009 Ingår i: VTC Spring 2009 - IEEE 69th Vehicular Technology Conference; Barcelona; Spain; 26 April 2009 through 29 April 2009. - 1550-2252. - 9781424425174 ; , s. Art. no. 5073788- Konferensbidrag (refereegranskat)abstract The next generation wireless systems based onOrthogonal Frequency Division Multiple Access (OFDMA) needto operate in widely different deployment and usage scenarios. Thus, support for flexible resource allocation is important. In this paper we investigate the performance of different memory-less and memory-based channel estimators with different OFDMA subcarrier allocation schemes and different pilot patterns. We evaluate the performance in various fading environments and for different user terminal velocities. The results show that channel estimation can perform well enough for time-frequency localized resources as small as 22 channel symbols with two pilots in many important scenarios. The results provided can be used to identify appropriate subcarrier allocations for the next generation OFDMA based wireless systems.
9.	Bernadó, Laura, et al. (författare) In-tunnel vehicular radio channel characterization 2011 Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327 Konferensbidrag (refereegranskat)abstract Abstract in UndeterminedInside a tunnel, electromagnetic wave propagation differs strongly from the well understood "open-air" situation. The characterization of the tunnel environment is crucial for deploying vehicular communication systems. In this paper we evaluate vehicle-to-vehicle (V2V) radio channel measurements inside a tunnel. We estimate the time-varying root mean square (rms) delay and Doppler spreads, as well as the excess delay and the maximum Doppler dispersion. The fading process in V2V communications is inherently non-stationary. Hence, we characterize the stationarity time, for which we can consider the fading process to be wide sense stationary. We show that the spreads, excess delay, and maximum Doppler dispersion are larger on average when both vehicles are inside the tunnel compared to the "open-air" situation. The temporal evolution of the stationarity time is highly influenced by the strength of time-varying multipath components and the distance between vehicles. Furthermore, we show the good fit of the rms delay and Doppler spreads to a lognormal distribution, as well as for the stationarity time. From our analysis we can conclude that the IEEE 802.11p standard will be robust towards inter-symbol and inter-carrier interference inside a tunnel.
10.	Botella Mascarell, Carmen, 1979, et al. (författare) On the performance of joint processing schemes over the cluster area 2010 Ingår i: IEEE Vehicular Technology Conference Spring, Taipei, Taiwan, May 2010. - 1550-2252. - 9781424425181 ; 2010-January, s. 1-5 Konferensbidrag (refereegranskat)abstract In this paper, three joint processing schemes for the downlink are characterized and compared within a cluster of base stations. The motivation of this study is to analyze the performance of these schemes over the cluster area, as a first step towards designing an adaptive joint processing scheme supporting dynamic usage scenarios. Each one of the analyzed schemes, the centralized, partial and distributed joint processing approaches, requires a different amount of available channel knowledge at the transmitter side, inter-base information exchange and feedback from the users. In addition, these schemes show varying capabilities to serve the users depending on their location in the cluster area. Therefore, in a real scenario, an adaptive joint processing scheme encompassing the three schemes could be used by the cluster of base stations. Simulation results show that, assuming coherent transmission, the centralized joint processing scheme outperforms with 25% the partial joint processing scheme and with 50% the distributed joint processing approach in the cell edge when a backhaul-load weighted average sum-rate per cell metric is taken into account.
11.	Chen, Jingjing, 1982, et al. (författare) Demonstration of analog millimeter-wave fronthaul for 64-QAM LTE transmission 2015 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. Konferensbidrag (refereegranskat)abstract Centralized baseband architecture is believed to be cost efficient and to offer high network performance. The fronthaul network, connecting the centralized baseband to distributed remote radios, requires high capacity and low latency transport links, due to the stringent specifications of the data interface, known as common public radio interface (CPRI). Today, fronthaul links are mostly based on digital CPRI over fibers, although it is possible to realize CPRI over wireless technology with the drawback of poor bandwidth efficiency. In this paper, we propose an analog wireless fronthaul concept to enable bandwidth efficient and scalable fronthaul networks. The basic idea is to transport narrow band analog radio signals over millimeter-wave bands instead of multi-gigabit digital signals. The phase and frequency impairments introduced by high frequency carriers are effectively reduced using an analog pilot-based mitigation technique. As a proof-of-concept demonstration, an analog fronthaul link is implemented, and the link performance is verified for 20 MHz 64-QAM LTE transmission over 70/80 GHz (E-band). The measured error vector magnitude (EVM) is about 3% with 10% pilot bandwidth overhead.
12.	Chen, Jingjing, 1982, et al. (författare) Experimental demonstration of RF-pilot-based phase noise mitigation for millimeter-wave systems 2014 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781479944491 ; , s. Art. no. 6965978- Konferensbidrag (refereegranskat)abstract Millimeter-wave bands are gaining popularity for high data rate wireless communication systems due to the wide available bandwidth. However, oscillator phase noise also increases as the carrier frequency increases. Methods of phase noise mitigation are therefore crucial for future millimeter-wave systems. In this work, we propose to adopt analog phase noise mitigation using an RF-pilot tone, which reduces both phase and frequency impairments of an arbitrary millimeter-wave signal at the expense of reduced spectral efficiency. The method is verified experimentally at carrier frequency of 28 GHz and E-band 73 GHz showing a 20 dB noise reduction up to 100 kHz offset. Since the method relaxes phase noise requirement it is attractive for phase noise sensitive technologies at high carrier frequency, such as OFDM used in LTE. As indicated by the simulation results, the reduced phase noise enables a LTE signal on a millimeter-wave carrier with marginal performance impact.
13.	Cinque, Elena, et al. (författare) Toward a Standard-Compliant Implementation for Consensus Algorithms in Vehicular Networks 2018 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2018-August Konferensbidrag (refereegranskat)abstract Cooperative Intelligent Transport System (C-ITS) applications require a continuous exchange of information between road users and roadside infrastructures. In this regard, distributed consensus algorithms can play an essential role in the definition of the information exchange rules between an ITS station and its neighbors. Although the consensus approach for networked systems is well-established, the efficiency of consensus methods under real-world vehicular communication constraints is largely unknown. This paper provides an ITS standard-compliant framework for analysis of consensus algorithms in vehicular networks with an emphasis on the role of robustness to changes in network topology in highly dynamic and dense environments. Our simulations reveal that in regular traffic conditions, the implemented consensus algorithm is able to achieve good performances in terms of both convergence time and needed consensus iterations. However, numerical results demonstrate that under dense and high-mobility traffic conditions the frequent exchange of large amounts of range information increases the Channel Busy Ratio (CBR) of the vehicular network and reduces the effectiveness of the algorithm as well.
14.	Coldrey, Mikael, 1972, et al. (författare) Higher order MIMO outdoor-to-indoor measurements using repeaters 2010 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424425198 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract In this paper we present results from a outdoor- to-indoor MIMO measurement campaign where we study the effect of repeaters on singular values, spatial richness, capacity, and delay spread distributions. We present results from different repeater scenarios such as, e.g. different outdoor/indoor repeater deployments with single/dual polarized antennas. The measurements show that repeaters significantly enhance the received SNR while they increase the delay spread and decrease the spatial richness of the MIMO channel. However, the main conclusion is that a significant increase in channel capacity is attained when deploying repeaters mostly thanks to their ability to provide spatial multiplexing over the high-quality eigenmodes they may provide. The number of such eigenmodes is limited by the number of repeaters, deployment, and their antennas. © 2010 IEEE.
15.	Deumal, M., et al. (författare) Constrained clipping for peak power reduction of multicarrier systems by tone reservation 2007 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 1424402662 ; , s. 2195-2199 Konferensbidrag (refereegranskat)abstract In this paper we introduce a new method to limit the peak factor of a multicarrier signal based on tone reservation. A peak-reducing signal is computed by clipping the original OFDM symbol. The peak-reducing signal is forced to have the constraints of tone reservation, so that when added to the original signal, the peak factor is reduced without increasing the BER and the out-of-band radiation. The proposed method has low computational complexity requirements and is fast-converging. Moreover, simulation results show that it has higher PAPR-reduction capabilities than other PAPR-reducing methods based on TR in the literature. © 2007 IEEE.
16.	Fang, Chao, 1991, et al. (författare) HARQ in Poisson Point Process-based Heterogeneous Networks 2015 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781479980888 ; 2015 Konferensbidrag (refereegranskat)abstract Hybrid automatic repeat request (HARQ) plays animportant role in improving the transmission efficiency and the robustness of wireless networks. Considering K-tier heterogeneous networks (HetNets) and modelling the locations of the base stations (BSs) as a homogeneous Poisson point process (PPP), this paper investigates the performance of HetNets implementing HARQ. We give closed-form expressions for the coverage probability and the per-user throughput with HARQ and show that using HARQ can indeed improve the coverage probability. However, depending on the channel conditions, the per-userthroughput of the HetNets may decrease by the implementation of HARQ. Furthermore, we show that the small cell density has negligible effect on the coverage probability and per-user throughput, and the per-user throughput may increase with the small cell path loss.
17.	Gan, Mingming, et al. (författare) Modeling time-variant fast fading statistics of mobile peer-to-peer radio channels 2011 Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327 Konferensbidrag (refereegranskat)abstract Abstract in UndeterminedThe radio channels between nodes of an indoor peer-to-peer network show specific fast fading characteristics. Depending on the mobility and on the scattering properties of the environment, different kinds of fading distributions can occur: Ricean fading between static nodes, but also Rayleigh or even double-Rayleigh fading between mobile nodes. We investigate fast fading in indoor peer-to-peer networks based on radio channel measurements. It turns out that the fading statistics change over time. While the predominant fading mechanism is a combination of Rayleigh and double-Rayleigh fading, Ricean fading also occasionally occurs. On top of that, indoors, the statistics of the fast fading change over time even for small-motions of the nodes, since the propagation environment is inhomogeneous. We comprehensively model these effects using a hidden Markov model, parameterized from our measurements. The model is validated, revealing a convincing fit between the model and the measurements.
18.	Gunnarsson, Fredrik, et al. (författare) Downtilted Base Station Antennas - A Simulation Model Proposal and Impact on HSPA and LTE Performance 2008 Ingår i: Proceedings of the 68th IEEE Vehicular Technology Conference. - 9781424417223 - 9781424417216 ; , s. 1-5 Konferensbidrag (refereegranskat)abstract This paper proposes a low-complexity model for vertical antenna radiation patterns, e.g. for inclusion in system- level simulations. They can be seen as extensions to the horizontal radiation pattern model used in 3GPP simulation scenarios. The model is verified against and compared to predicted and measured data from real networks. The impact on system-level performance is also investigated. It is seen that using the proposed model, simulated geometry distributions and soft handover statistics closely matching those of real networks may be achieved. The analysis also concludes that many real networks have better cell isolation than what is modeled by the 3GPP antenna model. As a consequence, the horizontal radiation pattern model significantly under-estimates the system level performance in such networks. Furthermore, the proposed model is used to assess the LTE and HSPA system-level performance for realistic scenarios.
19.	Gunnarsson, Fredrik, et al. (författare) Post-processing of drive test measurements using spatial filtering 2004 Ingår i: IEEE Vehicular Technology Conference (VTC) Proceedings. - : IEEE. - 1550-2252. ; 1, s. 79-83 Tidskriftsartikel (refereegranskat)abstract Drive tests are important means to evaluate critical properties of a wireless network in operation. The network coverage is vital, and therefore, the received power of pilot signals from the base stations are monitored to estimate the spatial distributions and variations of the power gain. With uniform time-sampling and a varying velocity, the typical temporal filter fails to extract the interesting information. In this paper we apply convolutional spatial filtering, both causal and non-causal, to resolve the problem. Relations to spatial data analysis methods are also commented upon. Simulations indicate significant improvements.
20.	Gustafson, Carl, et al. (författare) Directional analysis of measured 60 GHz indoor radio channels using SAGE 2011 Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327 Konferensbidrag (refereegranskat)abstract Abstract in Undetermined Directional properties of the radio channel are of high importance for the development of reliable wireless systems operating in the 60 GHz frequency band. Using transfer functions measured from 61 to 65 GHz in a conference room we have extracted estimates of the multi-path component parameters using the SAGE algorithm. In the paper we compare results for line-of-sight (LOS) scenarios and the corresponding non-line-of-sight (NLOS) scenarios and present values of the direction spread at the Tx and the Rx.
21.	Haneda, Katsuyuki, et al. (författare) Feasibility study of a mm-wave impulse radio using measured radio channels 2011 Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327 Konferensbidrag (refereegranskat)abstract Abstract in UndeterminedA millimeter-wave (mm-wave) impulse radio is an attractive alternative to existing high-speed mm- wave radio systems because of the potential for a simpler transceiver architecture. This paper studies the feasibility of a mm-wave impulse radio system for home and office use by considering state-of-the- art transceivers and multiple-input multiple-output measured propagation channels as well as the IEEE 802.15.3c channel model. Our analysis reveals that reliable data transmission is infeasible even in line-of-sight (LOS) scenarios because of a low power level at the Rx if we do not use beamforming. However, introducing 7×7 beamforming at the Tx dramatically improves the coverage beyond 5 m distance in the LOS scenario and up to 5 m in a non- line-of-sight (NLOS) scenario, though the performance varies in the NLOS scenario, depending on the Tx and Rx locations. We propose an adaptive transmit signaling scheme that adjusts the pulse repetition frequency depending on the delay dispersion of the propagation channel in order to avoid intersymbol interference and keep the Rx structure simple. The proposed transmit signaling scheme leads to a pulse transmission rate of 250 Mpulses/s in all measured channels while the rate is lower when the 802.15.3c model is considered because of a more multipath-rich characteristics than our measured channels.
22.	Haneda, Katsuyuki, et al. (författare) Spatial Degrees-of-Freedom of 60 GHz Multiple-Antenna Channels 2013 Ingår i: [Host publication title missing]. - 1550-2252. Konferensbidrag (refereegranskat)abstract This paper studies the potential of spatial multiplexing for measured 60 GHz radio channels by estimating the number of eigenchannels. It is well-known that the number of available eigenchannels is dependent on a propagation channel condition as well as antenna array conguration. We evaluate a spatial degrees- of-freedom (SDoF) metric that depends on the propagation conditions and the antenna aperture size, but is otherwise independent of the realization of antenna elements on the aperture. The SDoF metric is a measure of the effective number of antenna elements for spatial multiplexing. We evaluate the SDoF for 60 GHz multiple-input multiple-output channels measured in a conference room environment under a line-of- sight (LOS) condition. Our analysis reveals that the SDoF is more than one for a transmit- receive antenna separation of more than 2 m, which indicates that spatial multiplexing can work in such LOS scenarios. Our results indicate that using only 10 antenna elements at each of the transmit and receive antenna aperture is sufficient for effective spatial multiplexing performance in the considered propagation scenario. Furthermore, by using just 5 antennas at each aperture, eigenchannels down to −15 dB relative magnitude can still be captured.
23.	Harrysson, Fredrik, et al. (författare) Dual antenna terminals in an indoor scenario 2006 Ingår i: [Host publication title missing]. - 1550-2252. ; 6, s. 2737-2741 Konferensbidrag (refereegranskat)abstract The performance of two different dual antenna hand-held test mobile terminals has been investigated in a realistic indoor office environment and scenario, with respect to antenna performance, diversity combining and Shannon MIMO channel capacity. Measurements of a 2times2 MIMO channel at 1877.5 MHz (narrowband) were performed using a dual-polarized base station antenna. Analyses show that diversity gains, using ideal selection combining and maximum ratio combining, between 0.7 and 4.6 dB was achieved at the 10% outage probability level. Ideal dual-side beamforming (single branch) gives up to 3.3 dB capacity gain compared to single antenna systems at SNR less than 10 dB, however, decreases with rising SNR. Dual branch MIMO capacity gain is only significant at higher SNR above 10 dB. In addition, horizontal polarization at the base station was found to outperform vertical polarization in this scenario
24.	Harrysson, Fredrik, et al. (författare) The composite channel method : Efficient experimental evaluation of a realistic MIMO terminal in the presence of a human body 2008 Ingår i: 2008 IEEE 67th Vehicular Technology Conference-Spring, VTC. - 1550-2252. - 9781424416455 ; , s. 473-477 Konferensbidrag (refereegranskat)abstract The immediate environment of the transmit (TX) and receive (RX) antennas, including the antenna casings and the users holding the antennas, has a strong impact on the propagation channel and thus on wireless systems. In this paper we experimentally evaluate a method that synthetically combines double-directional measurements of the propagation channel (without the user influence) with measured antenna patterns of antennas-plus-users, by comparing obtained sample results with direct measurements in the same environment. The measurements are done for a static microcell 8×4 MIMO scenario at 2.6 GHz. A realistic user phantom was used together with a test terminal prototype with four antenna elements, and a number of different configurations and orientations of the phantom were tested. In average over all test cases, the mean signal power deviation between composite channel method and measurements was well within 1 dB. The composite method shows 6% higher terminal antenna correlation but similar statistical distributions as the measured. The differences between the model and measurements for the strongest eigenvalue (relevant for MRC combining) was found to be within 1 dB above 10% outage level. Relative deviations in the ergodic MIMO capacity were smaller than 10%.
25.	Harrysson, Fredrik, et al. (författare) The Composite Channel Method: Efficient Experimental Evaluation of Realistic MIMO Terminal in the Presence of Human Body 2008 Ingår i: Proc. IEEE VTC 2008 spring, Singapore, May 2008. - 1550-2252. ; , s. 473-477 Konferensbidrag (refereegranskat)
26.	He, Jiguang, et al. (författare) Large Intelligent Surface for Positioning in Millimeter Wave MIMO Systems 2020 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2020-May Konferensbidrag (refereegranskat)abstract Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large bandwidth and inherently high angular resolution. In this paper, we introduce the newly invented concept, large intelligent surface (LIS), to mmWave positioning systems, study the theoretical performance bounds (i.e., Cramér-Rao lower bounds) for positioning, and evaluate the impact of the number of LIS elements and the value of phase shifters on the position estimation accuracy compared to the conventional scheme with one direct link and one non-line-of-sight path. It is verified that better performance can be achieved with a LIS from the theoretical analyses and numerical study.
27.	Hoang, Le-Nam, 1984-, et al. (författare) Low Complexity Algorithm for Efficient Relay Assignment in Unicast/Broadcast Wireless Networks 2017 Ingår i: 2017 IEEE 85th Vehicular Technology Conference (VTC Spring). - : IEEE. - 9781509059324 - 9781509059331 ; June Konferensbidrag (refereegranskat)abstract Using relayers in wireless networks enables higher throughput, increased reliability or reduced delay. However, when building networks using commercially available hardware, concurrent transmissions by multiple relayers are generally not possible. Instead one specific relayer needs to be assigned for each transmission instant. If the decision regarding which relayer to assign, i.e., which relayer that has the best opportunity to successfully deliver the packet, can be taken online, just before the transmission is to take place, much can be gained. This is particularly the case in mobile networks, as a frequently changing network topology considerably affects the choice of a suitable relayer. To this end, this paper addresses the problem of online relay assignment by developing a low-complexity algorithm highly likely to find the optimal combination of relaying nodes that minimizes the resulting error probability at the targeted receiver(s) using a mix of simulated annealing and ant colony algorithms, such that relay assignments can be made online also in large networks. The algorithm differs from existing works in that it considers both unicast as well as broadcast and assumes that all nodes can overhear each other, as opposed to separating source nodes, relay nodes and destination nodes into three disjoint sets, which is generally not the case in most wireless networks.
28.	Huang, Binru, et al. (författare) Joint Scheduling for Multi-Service in Coordinated Multi-Point OFDMA Networks 2012 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781467309905 ; , s. Art. no. 6240135- Konferensbidrag (refereegranskat)abstract In this paper, the issues upon user scheduling in the downlink packet transmission for multiple services are addressed for coordinated multi-point (CoMP) OFDMA networks. We consider mixed traffic with voice over IP (VOIP) and best effort (BE) services. In order to improve cell-edge performance and guarantee diverse quality of service (QoS), a utility-based joint scheduling algorithm is proposed, which consists of two steps: ant colony optimization (ACO) based joint user selection and greedy subchannel assignment. We compare the proposed algorithm with the greedy user selection (GUC) based scheme. Via simulation results, we show that 95% of BE users are satsified with average cell-edge data rate greater than 200kbps by using either of the two algorithms. Whereas, our proposed algorithm ensures that more than 95% of VoIP users are satisfied with packet drop ratio less than 2%, compared to 78% by the GUC based algorithm.
29.	Huynh, Khoa Quang, 1984, et al. (författare) Improved iterative decoders for turbo-coded decode-and-forward relay channels 2012 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. Konferensbidrag (refereegranskat)abstract An Improved Maximum A Posteriori (IMAP) decoder for turbo-coded decode-and-forward (DF) relay channels which takes into account the decoding errors at the relay is analyzed. This decoder is implemented in an iterative manner similar to the traditional iterative decoder (TID) used for turbo codes. The performance of this IMAP decoder is compared with the performance of an iterative decoder normally used in the literature which does not take into account the decoding errors at the relay, by simulation. The comparison shows that although the proposed IMAP decoder provides a better performance, especially when many decoding errors occur at the relay, the improvement is not significant. Then, another heuristic modification for the iterative decoder is proposed. In spite of the lack of theoretical analysis, the numerical results show that the proposed heuristically modified iterative decoder (HMID) gives significantly better performance than the traditional one.
30.	Ingason, Tryggvi, 1983, et al. (författare) Impact of frequency selective channels on a line-of-sight MIMO microwave radio link 2010 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424425198 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Two line-of-sight (LoS) multiple-input multipleoutput (MIMO) systems for point-to-point microwave radio links are simulated and analyzed. Both 2×2 spatially-separated, singlepolarized and 4×4 spatially-separated, dual-polarized systems are considered in the presence of a frequency selective and time varying channel. Time dependence is introduced by moving the antennas during the simulation and thereby introducing the need for an adaptive space-time-equalizer (STE). Our results indicate that a time-varying frequency selective LoS MIMO channel puts higher requirements on the STE and introduces a higher SNR penalty compared to a single-input single-output (SISO) system. © 2010 IEEE.
31.	Javidsharifi, Mahshid, et al. (författare) PV-Powered Base Stations Equipped by UAVs in Urban Areas 2022 Ingår i: 2022 IEEE 96th Vehicular Technology Conference, VTC 2022-Fall 2022 - Proceedings. - 1550-2252. - 9781665454681 ; 2022-September Konferensbidrag (refereegranskat)abstract Recently, the application of unmanned aerial vehicles (UAVs) to support the base stations in cellular telecommunication networks attracts attentions. UAV-assisted base stations can provide the extra users' demand in extreme and/ or unpredictable situations such as Olympic Games to avoid extra cost of installing ground base stations. In this paper, a PV-battery power system is presented to supply UAV-assisted base stations in cellular telecommunication networks in urban areas to prevent environmental issues as well as to reduce the cost of fulfilling the energy demand. First, the energy consumption profile of the batteries of UAVs is estimated. Afterwards, the impact of the PV system sizing and battery capacity are studied based on sensitivity analysis.
32.	Johanson, Matthias, et al. (författare) Joint subjective and objective data capture and analytics for automotive applications 2017 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781509059355 Konferensbidrag (refereegranskat)abstract In this paper we describe a novel technological framework for capture and analysis of both objective measurement data and subjective user experience data for automotive applications. We also investigate how the framework can be extended to address privacy issues by enforcing a rigorous privacy model called differential privacy. The system under development integrates a telematics system with a smartphone app service architecture and a data-driven analytics framework. The hypothesis is that the framework will improve the opportunities of conducting large scale user trials of automotive functions and services, while improving the quality of collected data. To achieve this, a number of challenges are addressed in the paper, including how to design the subjective data capture mechanisms to be both simple to use yet powerful, how to correlate subjective data with objective measurement data, and how to protect the privacy of users.
33.	Johansson, Anders J, et al. (författare) MIMO channel measurements for personal area networks 2005 Ingår i: [Host publication title missing]. - 1550-2252. - 0780388879 ; 61:1, s. 171-176 Konferensbidrag (refereegranskat)abstract This paper analyzes MIMO propagation channels for personal area networks. Such channels show important differences to propagation channels in wide-area networks, due to the different environments in which the systems are operated, as well as due to different mobility models, ranges, and presence of humans in the environment, and the impact of the antenna arrangement. We present results from a recent measurement campaign for this type of channel. We first analyze the requirements for measurement setups, especially in terms of different positions and orientations of the antenna arrays, to obtain meaningful results. We then analyze the measured data and present results for path loss, power delay profiles, spatial correlation and temporal correlation.
34.	Karout, Johnny, 1985, et al. (författare) Performance Trade-off Investigation of B-IFDMA 2009 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424425143 ; 1-4, s. 368-372 Konferensbidrag (refereegranskat)abstract A performance trade-off investigation is carried out between different possible uplink multiple access schemes, that are based on Orthogonal Frequency Division Multiplexing (OFDM), for International Mobile Telecommunication (IMT) Advanced systems. Between the Discrete Fourier Transform (DFT) precoded systems with different subcarrier allocation mappings and systems lacking DFT-precoders, Block Interleaved Frequency Division Multiple Access (B-IFDMA) is shown to provide a good trade-off between the frequency diversity collected, envelope properties achieved, and channel estimation performance compared to the other mapping schemes. The schemes are analyzed in the presence of the different possible modules which include equalizers, modulators, interleavers, and channel codes. In particular, robust codes such as Turbo codes are able to collect the diversity provided by such schemes, and B-IFDMA systems is shown to be able to beat the other systems in bit error rate (BER) performance terms.
35.	Kletsov, Andrey, et al. (författare) A General Simulation Framework for Radiative Wireless Power Transfer Systems Based On Phased-Array Transmitters 2023 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2023-June Konferensbidrag (refereegranskat)abstract Radiative wireless power transfer (WPT) is an emerging technology for charging moving objects (e.g., vehicles) or static user terminals (e.g., mobile handsets). The most popular radiative WPT techniques employ transmitter (TX) and receiver (RX) phased arrays with dynamic beamforming functionalities. In this paper, we present a simulation approach capable of accurately estimating main WPT characteristics such as received power and power transfer efficiency. The method employs the equivalence principle to approximate TX and RX antenna apertures during the charging process, whereas antenna coupling is computed using the reaction concept. We demonstrate several multi-RX charging examples for different amplitude-only TX autofocusing algorithms. The discussion is complemented by an RX rectifier performance consideration.
36.	Koirala, Remun, et al. (författare) Direction Aided Multipath Channel Estimation for Millimeter Wave Systems 2021 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2021-April Konferensbidrag (refereegranskat)abstract In this paper, we present a low-latency direction assisted channel estimation algorithm suitable for millimeter wave (mm-Wave) systems. First, during the beam training procedure, we perform angle of departure (AoD) and angle of arrival (AoA) measurements with their corresponding variances and based on them, we design both downlink and uplink beams. We then perform signal measurements with these beams and accordingly design the sensing matrix, while also iteratively refining the angle estimation and the beams for the next measurements accordingly. Finally, exploiting both the sparseness and the intrinsic geometric nature of the mm-Wave channel, we apply compressive sensing tools so as to complete the estimation procedure. Simulations show that the corresponding estimation error decreases rapidly in comparison with other conventional approaches.
37.	Kåredal, Johan, et al. (författare) Radio channel measurements at street intersections for vehicle-to-vehicle applications 2010 Ingår i: IEEE 71st Vehicular Technology Conference (VTC 2010-Spring), 2010. - 1550-2252. ; , s. 1-5 Konferensbidrag (refereegranskat)abstract This paper presents the results of an empirical study of wireless propagation channels for vehicle-to-vehicle communications in street intersections, a scenario especially important for collision avoidance applications. The results are derived from a channel measurement campaign performed at 5.6 GHz in four different types of urban intersections. We present results on typical power delay profiles, pathloss and delay spreads and discuss important propagation mechanisms. By comparing the results of the different intersections, we find that absence of line-of-sight is problematic for system coverage, especially when there are few other significant scattering objects in and around the intersection. Roadside buildings can create important propagation paths that account for a considerable part of the total received power.
38.	Kåredal, Johan, et al. (författare) Shadowing effects in MIMO channels for personal area networks 2006 Ingår i: [Host publication title missing]. - 1550-2252. ; , s. 173-177 Konferensbidrag (refereegranskat)abstract In this paper we analyze the effects of body shadowing in multiple-input-multiple-output (MIMO) channels used for personal area networks (PANs). We give physical reasoning to why PANs may experience two different types of shadowing, and to support our argument, we present results from a measurement campaign for three different PAN channels with human influence. The campaign is performed using different types of multi-element antenna devices; an access point, a body-worn device and two hand-held devices, conducted over a series of distances between 1-10 m. For each distance, a number of channel realizations are obtained by moving the antenna devices over a small area, and by rotating the persons holding the devices. The results show that it is suitable to distinguish between body shadowing (due to the rotation of the person holding the device) and shadowing due to surrounding objects (lateral movement). We also present a statistical model where the two types of shadowing are described as separate log-normal processes. Furthermore, we find that body shadowing has a big influence on the capacity of the investigated PAN channels. © 2006 IEEE.
39.	Lakshmana, Tilak Rajesh, 1980, et al. (författare) Partial joint processing for frequency selective channels 2010 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424435746 Konferensbidrag (refereegranskat)abstract In this paper, we consider a static cluster of base stations where joint processing is allowed in the downlink. The partial joint processing scheme is a user-centric approach where subclusters or active sets of base stations are dynamically defined for each user in the cluster. In frequency selective channels, the definition of the subclusters or active set thresholding of base stations can be frequency adaptive (per resource block) or non-adaptive (averaged over all the resource blocks). Frequency adaptive thresholding improves the average sum-rate of the cluster, but at the cost of an increased user data interbase information exchange with respect to the non-adaptive frequency thresholding case. On the other hand, the channel state information available at the transmitter side to design the beamforming matrix is very limited and rank deficiency problems arise for low values of active set thresholding and users located close to the base station. To solve this problem, an algorithm is proposed that defines a cooperation area over the cluster where the partial joint processing scheme can be performed, frequency adaptive or non-adaptive, for a given active set threshold value.
40.	Lakshmana, Tilak Rajesh, 1980, et al. (författare) Partial Joint Processing with Efficient backhauling in Coordinated MultiPoint Networks 2012 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781467309905 Konferensbidrag (refereegranskat)abstract Joint processing between base stations is a promising technique to improve the quality of service to users at the cell edge, but this technique poses tremendous requirements on the backhaul signaling capabilities. Partial joint processing is a technique aimed to reduce feedback load, in one approach the users feed back the channel state information of the best links based on a channel gain threshold mechanism. However, it has been shown in the literature that the reduction in the feedback load is not reflected in an equivalent backhaul reduction unless additional scheduling or precoding techniques are applied. The reason is that reduced feedback from users yields sparse channel state information at the Central Coordination Node. Under these conditions, existing linear precoding techniques fail to remove the interference and reduce backhaul, simultaneously, unless constraints are imposed on scheduling. In this paper, a partial joint processing scheme with efficient backhauling is proposed, based on a stochastic optimization algorithm called particle swarm optimization. The use of particle swarm optimization inthe design of the precoder promises efficient backhauling with improved sum rate.
41.	Lau, Buon Kiong, et al. (författare) Capacity analysis for compact MIMO systems 2005 Ingår i: IEEE 61st Vehicular Technology Conference, VTC 2005-Spring. - 1550-2252. - 0780388879 ; 61:1, s. 165-170 Konferensbidrag (refereegranskat)abstract We analyze the impact of mutual coupling on the capacity of MEMO systems with compact antenna arrays. Existing studies present conflicting views on the effect of mutual coupling. This is, in part, due to their different scopes and underlying assumptions of the system setups. In this paper, we aim to give a comprehensive picture by first examining the impact of mutual coupling on three capacity-related performance measures: antenna correlation, efficiency and bandwidth. While the first two aspects have received significant attention, antenna bandwidth with mutual coupling is a relatively uncharted territory. We show that while implementing a good matching network can drastically improve the system capacity for narrowband systems in the presence of strong mutual coupling, the same conclusions may not necessarily apply to wideband cases. To exemplify this, we carry out capacity simulations for an end-to-end MIMO system, where a recently proposed S-parameter approach is used in conjunction with the 3GPP-3GPP2 channel model to model realistic wideband channel and antenna effects at both transmit and receive ends.
42.	Lautenbach, Aljoscha, 1985, et al. (författare) A Preliminary Security Assessment of 5G V2X 2019 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2019-April Konferensbidrag (refereegranskat)abstract Research on intelligent transport systems (ITS) for improved traffic safety and efficiency has reached a high level of maturity and first applications will hit the market in 2019. Since 2004, the wireless standard 802.11p has been developed specifically for ITS services. Since then new telecommunication standards have been devised, and the new 5G telecommunication standard is nearing completion. Due to its technological advantages such as higher speeds and reliability, it is being considered to be used for ITS services.The new radio technology “NewRadio (NR)”, which is being developed as part of 5G, can complement or replace 802.11p in V2X applications. While there has been some work to compare 802.11p and 5G New Radio in terms of performance and applicability for safety-critical use cases, little work has been done to investigate the implications for security. In this paper, we provide an overview of the security requirements of known ETSI ITS use cases, and based on those use cases we compare and assess the security implications of replacing 802.11p with cellular V2X. We find that due to the use of millimeter waves, beamforming and massive MIMO, there will be an implicit improvement for confidentiality and privacy, and it may also be possible to shorten authentication procedures in certain cases. When a fully network-assisted C-V2X mode is chosen, it is also possible to outsource several of the ITS security requirements to the cellular network.
43.	Li, Jingya, 1986, et al. (författare) A novel frequency reuse scheme for coordinated multi-point transmission. 2010 Ingår i: IEEE Vehicular Technology Conference Spring, Taipei, Taiwan, May 2010. - 1550-2252. - 9781424425198 ; , s. 1-5 Konferensbidrag (refereegranskat)abstract Coordinated Multi-Point (CoMP) transmission is considered in 3GPP LTE-Advanced as a key technique to improve the cell-edge performance. In order to support joint resource allocation among coordinate cells in CoMP systems, efficient frequency reuse schemes need to be designed. However, most of the existing frequency reuse schemes are not suitable for CoMP transmission due to not considering multi-cell joint transmission scenario in their frequency reuse rule. To solve this problem, a cooperative frequency reuse (CFR) scheme is proposed in this paper, which divides the cell-edge area of each cell into two types of zones, and defines a frequency reuse rule to support CoMP transmission for users in these zones. Compared with the conventional soft frequency reuse (SFR) scheme, simulation results demonstrate that the CFR scheme reduces the blocking probability by more than 50%, and improves the cell-edge throughput by 30~40%, with 5~9% additional cell-average throughput.
44.	Li, Jingya, 1986, et al. (författare) Joint Scheduling and Power Control in Coordinated Multi-Point Clusters 2011 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424483273 ; , s. Art. no. 6092837- Konferensbidrag (refereegranskat)abstract In this paper, we address the problem of designing a joint scheduling and power control algorithm in a downlink coordinated multi-point (CoMP) cluster supporting CoMP joint transmission. The objective is to maximize the cell-edge throughput under per-point power constraints. By an analytical derivation, binary power control is proved to be the optimal solution for any given selected user group. Utilizing this analytical result, a centralized and a semi-distributed version of joint user selection and power control algorithms are proposed. Compared to algorithms without considering joint transmission and algorithms without considering power control, simulation results show that the proposed algorithms achieve a good trade-off between joint transmission and interference coordination, which helps to improve the cell-edge performance.
45.	Lioliou, Panagiota, 1982, et al. (författare) Bayesian Channel Estimation Techniques for AF MIMO Relaying Systems 2011 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424483273 ; , s. Art. no. 6093283- Konferensbidrag (refereegranskat)abstract In this paper, we consider the fundamental problem of channel estimation in multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems operating over random channels. Using the Bayesian framework, linear minimum mean square error (LMMSE) and expectation-maximization (EM) based maximum a posteriori (MAP) channel estimation algorithms are developed, that provide the destination with full knowledge of all channel parameters involved in the transmission. The performance of the proposed algorithms is evaluated in terms of the mean square error (MSE) as a function of the signal-to-noise ratio (SNR) during the training interval. Our simulation results show that the incorporation of prior knowledge into the channel estimation algorithm offers improved performance, especially in the low SNR regime.
46.	Lioliou, Panagiota, 1982, et al. (författare) Channel Tracking for AF MIMO Relaying Systems 2012 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781467322171 ; , s. 1-5 Konferensbidrag (refereegranskat)abstract In this paper, we consider the problem of channelestimation in multiple-input multiple-output (MIMO) amplifyand-forward (AF) relaying systems operating over time varyingchannels. Only data at the receiving end are assumed availablefor the estimation. By employing a first-order autoregressive(AR) model for characterizing the time-varying nature of thechannels to be estimated, we derive an expectation-maximization(EM) Kalman filter (KF) that utilizes the received signal at thedestination to track the individual channel links. The extendedKF algorithm is also derived and compared to the proposedEM-based KF. Our simulation results show that the proposedEM-based KF offers better estimation performance with lesscomplexity when compared to the EKF algorithm.
47.	Liu, Liang (författare) Energy-efficient MIMO detection using link-adaptive parameter adjustment 2013 Ingår i: IEEE 77th Vehicular Technology Conference (VTC Spring), 2013. - 1550-2252. - 9781467363365 ; , s. 1-5 Konferensbidrag (refereegranskat)
48.	Lu, Yi, et al. (författare) Joint RIS Calibration and Multi-User Positioning 2022 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2022-September Konferensbidrag (refereegranskat)abstract Reconfigurable intelligent surfaces (RISs) are expected to be a key component enabling the mobile network evolution towards a flexible and intelligent 6G wireless platform. In most of the research works so far, RIS has been treated as a passive base station (BS) with a known state, in terms of its location and orientation, to boost the communication and/or terminal positioning performance. However, such performance gains cannot be guaranteed anymore when the RIS state is not perfectly known. In this paper, by taking the RIS state uncertainty into account, we formulate and study the performance of a joint RIS calibration and user positioning (JrCUP) scheme. From the Fisher information perspective, we formulate the JrCUP problem in a network-centric single-input multiple-output (SIMO) scenario with a single BS, and derive the analytical lower bound for the states of both user and RIS. We also demonstrate the geometric impact of different user locations on the JrCUP performance while also characterizing the performance under different RIS sizes. Finally, the study is extended to a multiuser scenario, shown to further improve the state estimation performance.
49.	Maham, Behrouz, et al. (författare) Performance Analysis of Millimeter Wave CoMP Networks under Blockage 2021 Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2021-April Konferensbidrag (refereegranskat)abstract In this paper, a coordinated multi-point (CoMP) based mmWave communications operating over access links impaired by blockage is considered. By assuming realistic assumptions such as line-of-sight and non-line-of-sight channel components, fading, and random blockage, we propose a tractable analytical framework for mmWave communications. Moreover, the performance of the CoMP-based mmWave communication is evaluated by deriving the distribution of the received signal and presenting closed form expression for outage probability. Simulation results show the correctness of the analytical results and impact of blockage on the reliability of the mmWave communications.
50.	Makki, Behrooz, 1980, et al. (författare) Data Transmission in the Presence of Channel State Feedback and Outage Probability Constraint 2010 Ingår i: IEEE 72nd Vehicular Technology Conference. - 1550-2252. - 9781424435746 Konferensbidrag (refereegranskat)abstract Recently, substantial attention has been paid to increase the achievable rates of wireless networks using different kinds of limited channel state information (CSI) feedback. This paper aims to investigate the effect of limited CSI feedback on the achievable rates of power-limited block fading channels constrained to have limited outage probability. Considering different power allocation strategies and various fading conditions, the results are obtained for different outage probabilities and are compared with the case where there is no outage limitation. Simulation results show that 1) although the outage probability constraint reduces the channel average rate, its influence diminishes as the channel state information feedback or the input power increases, 2) the effect of the outage probability constraint decreases as the channel fading severity is reduced.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "L773:1550 2252 OR L773:9781424417223 "

Avgränsa träffmängd

År