| 1. |
- Björnson, Emil, Professor, 1983-, et al.
(författare)
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Designing Wireless Broadband Access for Energy Efficiency : Are Small Cells the Only Answer?
- 2015
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Ingår i: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOP (ICCW). - : IEEE. - 9781467363051 ; , s. 136-141
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Konferensbidrag (refereegranskat)abstract
- The main usage of cellular networks has changed from voice to data traffic, mostly requested by static users. In this paper, we analyze how a cellular network should be designed to provide such wireless broadband access with maximal energy efficiency (EE). Using stochastic geometry and a detailed power consumption model, we optimize the density of access points (APs), number of antennas and users per AP, and transmission power for maximal EE. Small cells are of course a key technology in this direction, but the analysis shows that the EE improvement of a small-cell network saturates quickly with the AP density and then "massive MIMO" techniques can further improve the EE.
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| 2. |
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| 3. |
- Böhm, Annette, 1975-, et al.
(författare)
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Data age based retransmission scheme for reliable control data exchange in platooning applications
- 2015
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Ingår i: 2015 IEEE International Conference on Communication Workshop (ICCW). - Piscataway, NJ : IEEE Press. - 9781467363051 ; , s. 2412-2418
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Konferensbidrag (refereegranskat)abstract
- Recent advances in cooperative driving hold the potential to significantly improve safety, comfort and efficiency on our roads. Platooning of heavy vehicles, where automated or semi-automated driving allows minimal inter-vehicle gaps, has shown considerable reductions in fuel consumption. Although using the same wireless communication technology, a platoon differs from a VANET (Vehicular Ad-hoc NETwork) in several points. It is centralized in its nature, with a well-defined group leader, its topology is fairly stable and it has very challenging requirements on timeliness and reliability of its control data exchange. Therefore, the IEEE 802.11p protocol suite and its recently defined message types do neither support the needs of a platooning application nor take advantage of its properties. A platoons control loop must continuously be fed with fresh data, so the information age is an important parameter to be closely monitored. In this paper, we therefore propose a framework for centralized channel access and retransmission capabilities for safety critical inter-platoon control data based on the data age of earlier received messages. A simulation evaluation compares our solution to a) the decentralized, standard-compliant IEEE 802.11p MAC (Medium Access Control) method, and a time-slotted scheme b) with and c) without retransmissions and shows that the centralized, data age based retransmission scheme clearly outperforms its competitors in terms of maintained data age. © 2015 IEEE.
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| 4. |
- Campolo, Claudia, et al.
(författare)
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Service Discovery and Access in Vehicle-to-Roadside Multi-Channel VANETs
- 2015
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Ingår i: 2015 IEEE International Conference on Communication Workshop. - Piscataway, NJ : IEEE Press. - 9781467363051 ; , s. 2477-2482
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Konferensbidrag (refereegranskat)abstract
- A wide portfolio of safety and non-safety services will be provided to drivers and passengers on top of Vehicular Ad Hoc Networks (VANETs).Non-safety services are announced by providers, e.g., road-side units (RSUs), on a channel that is different from the one where the services are delivered. The dependable and timely delivery of the advertisement messages is crucial for vehicles to promptly discover and access the announced services in challenging vehicle-to-roadside scenarios, characterized by intermittent and short lived connectivity.In this paper, we present an analytical framework that models the service advertisement and access mechanisms in multichannel vehicular networks.The model accounts for dual-radio devices, and computes the mean service discovery time and the service channel utilization by considering the disruption periods due to the switching of the RSU from the advertising channel (where announcements are transmitted) to the advertised channel (where services are exchanged), under different channel and mobility conditions. It provides quick insights on parameter settings to allow providers to improve service provisioning. © 2015 IEEE
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| 5. |
- Chen, Jingjing, 1982, et al.
(författare)
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A data-rate adaptable modem solution for millimeter-wave wireless fronthaul networks
- 2015
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Ingår i: 2015 IEEE International Conference on Communication Workshop, ICCW 2015. - 2164-7038. - 9781467363051 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- For dense small cell deployment in centralized baseband architecture, wireless fronthaul is a cost efficient and flexible alternative to fiber-based fronthaul links. Due to the available wide bandwidth, millimeter-wave technology is the most promising choice to realize multi-gigabit wireless transmission of the common public radio interface (CPRI). In this paper, we present a novel differential encoding scheme for differential quadrature phase-shift keying (D-QPSK) modulation, which enables data-rate adaptable CPRI transmission without modification of a standard receiver. A multi-rate D-QPSK modulator/demodulator (modem) is implemented and tested for data rates up to 10 Gbps, limited by the bandwidth of the microwave components in use. This modem is verified to fulfill the CPRI specifications with respect to multi-rate, low latency and high system performance. Therefore, it is proposed for the implementation of wireless CPRI links at millimeter-wave bands.
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| 6. |
- Chen, Lei, et al.
(författare)
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Design of in-building distributed antenna systems: mathematical models and efficient algorithms
- 2015
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Ingår i: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOP. - : IEEE. - 9781467363051 ; , s. 1497-1502
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Konferensbidrag (refereegranskat)abstract
- In order to provide sufficient coverage and capacity for indoor users, in-building distributed antenna system (IB-DAS) has been considered. A passive IB-DAS deploys distributed antennas inside the building and connects the antennas to a base station (BS) through coaxial cables and power equipment. Power is distributed from the BS to each of the antennas. We consider an optimal design of passive IB-DAS with the target to minimize the cable usage, together with the consideration of power distribution. We decompose the problem into two sub-problems, namely the topological design and the equipment selection. Mixed integer linear models are developed for solving the sub-problems. Local search is designed to combine the sub-problems and balance their objectives. Application over realistic IB-DAS deployment and comparison with previous studies demonstrate the effectiveness of the algorithm.
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| 7. |
- Chu, Thi My Chinh, et al.
(författare)
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Channel Reservation for Dynamic Spectrum Access of Cognitive Radio Networks with Prioritized Traffic
- 2015
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Ingår i: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOP. - : IEEE Communications Society. - 9781467363051 ; , s. 883-888
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a strategy to coordinate the dynamic spectrum access (DSA) of different types of traffic. It is assumed that the DSA assigns spectrum bands to three kinds of prioritized traffic, the traffic of the primary network, the Class 1 traffic and Class 2 traffic of the secondary network. Possessing the licensed spectrum, the primary traffic has the highest access priority and can access the spectrum bands at anytime. The secondary Class 1 traffic has higher priority compared to secondary Class 2 traffic. In this system, a channel reservation scheme is deployed to control spectrum access of the traffic. Specifically, the optimal number of reservation channels is applied to minimize the forced termination probability of the secondary traffic while satisfying a predefined blocking probability of the primary network. To investigate the system performance, we model state transitions of the DSA as a multi-dimensional Markov chain with three-state variables representing the number of primary, Class 1, and Class 2 packets in the system. Based on this chain, important performance measures, i.e., blocking probability and forced termination probability are derived for the Class 1 and Class 2 secondary traffic.
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| 8. |
- Cippitelli, E., et al.
(författare)
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Time synchronization and data fusion for RGB-Depth cameras and inertial sensors in AAL applications
- 2015
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Ingår i: 2015 IEEE International Conference on Communication Workshop, ICCW 2015. - : IEEE conference proceedings. - 9781467363051 ; , s. 265-270
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Konferensbidrag (refereegranskat)abstract
- Ambient Assisted Living applications often need to integrate data from multiple sensors, to provide consistent information on the observed phenomena. Data fusion based on samples from several sensors requires accurate time synchronization with sufficient resolution, depending on the sensor sampling frequency. This work presents a technical platform for the efficient and accurate synchronization of the data captured from RGB-Depth cameras and wearable inertial sensors, that can be integrated in AAL solutions. A case study of sensor data fusion for Timed Up and Go test is also presented and discussed.
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| 9. |
- Farhadi, Hamed, 1983-, et al.
(författare)
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Pilot-assisted opportunistic user scheduling for wireless multi-cell networks
- 2015
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Ingår i: IEEE International Conference on Communications. - : IEEE. - 9781467363051
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Konferensbidrag (refereegranskat)abstract
- We consider downlink transmission in multi-cell wireless networks where in each cell one base station is serving multiple mobile terminals. There is no a priori channel state information (CSI) available at base stations and mobile terminals. We propose a low-complexity pilot-assisted opportunistic user scheduling (PAOUS) scheme. The proposed scheme operates in four subsequent phases: channel training; feedback transmission; user scheduling; and data transmission. We deploy an orthogonal pilot-assisted channel training scheme for acquiring CST at mobile terminals. Consequently, each mobile terminal obtains a noisy estimation of the corresponding local CST (i.e. channel gains from base stations to the mobile terminal). Then, it makes a local decision based on the estimated channel gains of the interfering links (i.e. the links between base stations in neighboring cells and the mobile terminal) and sends a one-bit feedback signal to the base station of the corresponding cell. Each base station schedules one mobile terminal for communication. We compute the achievable rate region and the achievable degrees of freedom (DoF) of the proposed transmission scheme. Our results show that in a multi-cell network with K base stations and coherence time T, the total DoF K-opt (1 - K-opt/T) is achievable given that the number of mobile terminals in each cell scales proportional to signal-to-noise-ratio. Since limited radio resources are available, only a subset of base stations should be activated, where the optimum number of active base stations is K-opt = min {K, T/2}. This recommends that in large networks (K > T/2), select only a subset of the base stations to be active and perform the PAOUS scheme within the cells associated to these base stations. Our results reveal that, even with single antenna at base stations and no a priori CSI at terminals, a non-trivial DoF gain can be achieved. We also investigate the power allocation between channel training and data transmission phases. Our study shows that in large networks (many base stations) more power should be allocated to channel training while in dense networks (many mobile terminals in each cell) more power should be allocated for data transmission.
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| 10. |
- Garcia, Gabriel, 1985, et al.
(författare)
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Joint scheduling and localization in UWB networks
- 2015
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Ingår i: 2015 IEEE International Conference on Communication Workshop, ICCW 2015. - 9781467363051 ; , s. 724-729
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Konferensbidrag (refereegranskat)abstract
- Ultra-wide bandwidth (UWB) systems allow for accurate localization to tackle and complement the GPS-aided solutions, which are impractical in weak signal environments. We consider the problem of fast link scheduling in the medium access control (MAC) layer for UWB localization. We present an optimization strategy to perform robust ranging scheduling with localization constraints. Given the complexity of the optimal strategy, two different MAC-aware link selection heuristics are also proposed. Our results show that significant MAC delay reductions are possible through the use of simple local heuristics. © 2015 IEEE.
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