| 1. |
- Araújo, Marco, et al.
(författare)
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Satellite backhaul for macro-cells, as an alternative to optical fibre, to close the digital divide
- 2019
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Ingår i: 2019 IEEE Wireless Communications and Networking Conference (WCNC). - : IEEE. - 9781538676479 - 9781538676462
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Konferensbidrag (refereegranskat)abstract
- The lack of broadband access causes a serious risk of social exclusion, by preventing citizens from full social and economic participation in the society. To avoid this risk, the concept of subsidized rural networks was developed by the European Commission, in which an operator builds, maintains and operates a network (usually an open network) capable of providing at least a 100 Mbps connection to the subscribers; deployed in low density regions being publicly subsidized when unprofitable. In this article, we suggest a methodology to measure a realistic value for the average broadband used per subscriber at busy hour. We also present a simulation model for the backhaul infrastructure costs for very fast networks in rural areas to cover the last, and more expensive, 5% of the population, while comparing optical fibre with satellite for the middle mile from an economical and financial perspective.
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| 2. |
- Hu, Sha, et al.
(författare)
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Joint Modulus Zero-Forcing MIMO Detector
- 2019
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Ingår i: 2019 IEEE Wireless Communications and Networking Conference, WCNC 2019. - 1525-3511. - 9781538676462 ; 2019-April
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Konferensbidrag (refereegranskat)abstract
- We propose an improvement over a modulus zero-forcing (MZF) detector proposed earlier in [1] for multi-input multi-output (MIMO) detection, namely, the joint MZF (JMZF) detector. The MZF detector provides better detection-performance than a traditional ZF detector through preserving controllable interferences, which are mitigated later by nonlinear modulus arithmetic operation. However, the MZF detector has a constraint that the effective MIMO channel after modulus operation is diagonal, which yields separate detections on different transmit layers and is suboptimal. In this paper, we propose the JMZF detector by considering a general effective channel which can further boost the detection-performance.
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| 3. |
- Hu, Sha, et al.
(författare)
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On Time-of-Arrival Estimation in NB-IoT Systems
- 2019
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Ingår i: 2019 IEEE Wireless Communications and Networking Conference, WCNC 2019. - 1525-3511. - 9781538676462 ; 2019-April
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Konferensbidrag (refereegranskat)abstract
- We consider time-of-arrival (ToA) estimation for a device working in narrowband Internet-of-Things (NB-IoT) systems. Due to a limited 180 kHz bandwidth, the time-domain auto-correlation function (ACF) of transmitted NB positioning reference signal (NPRS) has a wide main-lobe. Without considering that, the performance of ToA estimation can be degraded for two reasons. Firstly, the NPRS corresponding to different received paths are superimposed on each other under multipath propagation. Secondly, the measured peak-to-average power-ratio (PAPR) for detecting the presence of NPRS is inaccurate. Therefore, in this letter we propose a space-alternating generalized expectation-maximization (SAGE) based method to estimate the number of channel taps, coefficients, and corresponding delays, with taking the imperfect ACF of NPRS into consideration. The proposed ToA estimator only uses time-domain cross-correlations between the received signal and the transmitted NPRS, which yields a low computational-cost. We show through simulations that, it performs close to maximum likelihood (ML) estimator under flat-fading channels, and is superior than traditional estimators under frequency-selective fading channels.
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| 4. |
- Høiland-Jørgensen, Toke, et al.
(författare)
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PoliFi: Airtime Policy Enforcement for WiFi
- 2019
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Ingår i: IEEE Wireless Communications and Networking Conference, WCNC. - : IEEE. - 9781538676462 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- As WiFi grows ever more popular, airtime contention becomes an increasing problem. One way to alleviate this is through network policy enforcement. Unfortunately, WiFi lacks protocol support for configuring policies for its usage, and since network-wide coordination cannot generally be ensured, enforcing policy is challenging. However, as we have shown in previous work, an access point can influence the behaviour of connected devices by changing its scheduling of transmission opportunities, which can be used to achieve airtime fairness. In this work, we show that this mechanism can be extended to successfully enforce airtime usage policies in WiFi networks. We implement this as an extension our previous airtime fairness work, and present PoliFi, the resulting policy enforcement system. Our evaluation shows that PoliFi makes it possible to express a range of useful policies. These include prioritisation of specific devices; balancing groups of devices for sharing between different logical networks or network slices; and limiting groups of devices to implement guest networks or other low-priority services. We also show how these can be used to improve the performance of a real-world DASH video streaming application.
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| 5. |
- Jahandideh, Mojtaba, et al.
(författare)
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Low Complexity Sparse Channel Estimation for Wideband mmWave Systems: Multi-Stage Approach
- 2019
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Ingår i: 2019 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC). - : IEEE. - 9781538676462
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of channel estimation in hybrid transceiver architectures operating in millimeter wave (mmWave) band. Due to the dynamic features of the environment and the sensitivity of mmWave bands to blockage and deafness, it is important to estimate mmWave channels with a low complexity and high performance algorithm. In this regard, we exploit the sparse structure of the frequency-selective mmWave channels and formulate the channel estimation problem as a sparse signal reconstruction in frequency domain. In order to solve the estimation problem, we propose a multi-stage based low complexity algorithm. Simulation results show that the proposed algorithm significantly reduces the computational complexity while preserving the quality of the estimation.
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| 6. |
- Mekuria, Fisseha, 1962-, et al.
(författare)
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Spectrum Sharing for Unlicensed 5G Networks
- 2019
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Ingår i: 2019 IEEE Wireless Communications and Networking Conference (WCNC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538676462
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Konferensbidrag (refereegranskat)abstract
- 5th generation wireless ICT eco-system promises three important pillars of network innovation: (a) Ultra Reliable Low Latency Communication, (b) Enhanced gigabits wireless broadband and (c) massive machine type communication. 5G is expected to transform the way humans and devices communicate and exchange services and improved automation of industry. The aim of this paper is to discuss recent research in spectrum sharing and unlicensed wireless networks, including its extension to 5G research based on use cases and associated technologies to address the requirements of affordable wireless broadband. The paper presents research contributions on spectrum toolboxes, including smart spectrum sharing for 5G and affordable networks. The research outcome will be presented with a proof of concept network test-bed developed in South Africa. Finally the paper will conclude with a challenge to existing and future research in technology standards for 5G to contribute towards the achievement of universal affordable broadband for the next billion customers.
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| 7. |
- Prasad, Ganesh, et al.
(författare)
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QoS-aware Power Allocation and Relay Placement in Green Cooperative FSO Communications
- 2019
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Ingår i: 2019 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC). - : IEEE. - 9781538676462
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Konferensbidrag (refereegranskat)abstract
- Due to increasing quality-of-service (QoS) demand in already congested radio spectrum, there is a need for designing energy-efficient free space optical (FSO) communication networks. Considering a realistic fading model incorporating the fluctuations in angle-of-arrival, we minimize the outage probability for error free transmission of high data volumes through optimizing the power allocation (PA) and relay placement (RP) in a dual-hop decode-and-forward (DF) relay-assisted cooperative FSO communication with coherent detection and direct link unavailability. As this problem is nonconvex, first the optimal PA between source and relay is obtained using a global optimization algorithm. Also, a closed form for the solution is obtained using a tight analytical approximation with the assumption that atmospheric turbulence over both the links is nearly same. Next, we optimize the RP followed by the outage probability is jointly minimized using alternating optimization algorithm. Numerical results validate the outage analysis and provide key insights on optimal PA and RP yielding an outage enhancement of around 37% over the benchmark scheme.
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| 8. |
- Tian, Guoda, et al.
(författare)
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Modified Gold Sequence for Positioning Enhancement in NB-IoT
- 2019
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Ingår i: 2019 IEEE Wireless Communications and Networking Conference, WCNC 2019. - 1525-3511. - 9781538676462 ; 2019-April
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Konferensbidrag (refereegranskat)abstract
- Positioning is an essential feature in Narrow-Band Internet-of-Things (NB-IoT) systems. Observed Time Difference of Arrival is one of the supported positioning techniques for NB-IoT. It utilizes the downlink NB positioning reference signal (NPRS) generated based on a length-31 Gold sequence. Although a Gold sequence has good auto-correlation and cross-correlation properties, the correlation properties of NPRS in NB-IoT are still sub-optimal. The reason is mainly due to two facts: the number of NPRS symbols in each subframe is limited, and the featured sampling-rate is low. In this paper, we propose to modify the NPRS generation by exploiting the cross-correlation function of the NPRS. That is, for each orthogonal frequency division multiplexing (OFDM) symbol we generate the first NPRS symbol as specified in the current standard, i.e., a Gold sequence; while the second OFDM symbol is set to the additive inverse of the first one. Our simulation results show that the proposed NPRS sequence results in improving the correlation properties, particularly with respect to the cross-correlation property. Furthermore, 15% -30% positioning-accuracy improvements can be attained with the proposed method, compared to the legacy one under both Additive White Gaussian Noise and Extended-Pedestrian-A channels. The proposed NPRS sequence can also be applied to other similar systems, such as long-term-evolution (LTE).
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| 9. |
- Yang, Hong, et al.
(författare)
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Can Massive MIMO Support Uplink Intensive Applications?
- 2019
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Ingår i: 2019 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC). - : IEEE. - 9781538676462
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Konferensbidrag (refereegranskat)abstract
- Current outdoor mobile network infrastructure cannot support uplink intensive mobile applications such as connected vehicles that collect and upload large amount of real time data. Our investigation reveals that with maximum-ratio (MR) decoding, it is theoretically impossible to support such applications with cell-free Massive MIMO, and it requires a very large number of service antennas in single cell configuration, making it practically infeasible; but with zero-forcing (ZF) decoding, such applications can be easily supported by cell-free Massive MIMO with very moderate number of access points (APs), and it requires a lot more service antennas in single cell configuration. Via the newly derived SINR expressions for cell-free Massive MIMO with ZF decoding we show that uplink power control is unnecessary, and that with 10 MHz effective bandwidth for uplink data transmission, in urban and suburban morphologies, on the 2 GHz band, 90/km(2) and 32/km(2) single antenna APs are enough to support 18 autonomous vehicles respectively. In rural morphology, using 450 MHz band, only 2/km(2) single antenna APs is enough.
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