| 1. |
- Elkotob, Muslim, et al.
(författare)
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Challenges and opportunities in content distribution networks: A case study
- 2012
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Ingår i: Proceedings of the 2012 IEEE Globecom Workshops (GC Wkshps). - : IEEE Communications Society. - 9781467349413 ; , s. 1021-1026
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Konferensbidrag (refereegranskat)abstract
- In this paper we present some contemporary examples of research-oriented as well as commercial content delivery networks (CDN)s. We discuss how both types of CDNs complement each other in tackling the posed technical and commercial challenges. We also show which performance metrics such as quality of experience (QoE) and time to first byte (TTFB) best capture the dynamics of traffic and services in CDNs. The core of this paper is our proposed network architecture for CDN providers/operators. The architecture combines video multicast optimized trees and cross-layer coordination between the physical DWDM layer (L1) and network layer (L3) for achieving higher efficiency and lower latency values for live streaming and on demand (VoD) video. Due to the pilot implementation of the presented concept being limited in scale, we use simulations in order to perform proof-of-concept on a sufficiently large environment. Results show that there is a strong correlation between the TTFB and QoE metrics with the former taking on values as low as 75 msec in a national 3-tier network.
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| 2. |
- Islam, Raihan Ul, et al.
(författare)
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Nomadic mobility between smart homes
- 2012
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Ingår i: Proceedings of the 2012 IEEE Globecom Workshops (GC Wkshps). - : IEEE Communications Society. - 9781467349413 ; , s. 1062-1067
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Konferensbidrag (refereegranskat)abstract
- Powerful, user-friendly mobile devices and cost-efficient wireless access technologies have lately changed the landscape for smart home environments to a large extent. Developments in the media landscape with large flat screens, new capturing devices, and large digital media libraries have also changed the way smart home environments are used. This paper presents and evaluates an architecture for nomadic mobility in such environments where end-users, by authenticating their terminals with a node in the home or visited environment using the infrastructure provided by the operator, easily can gain access to various types of resources at home while roaming to other people's home networks.
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| 3. |
- Seifi, Nima, 1981, et al.
(författare)
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Throughput optimization in MU-MIMO systems via exploiting bs antenna tilt
- 2012
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Ingår i: 2012 IEEE Globecom Workshops, GC Wkshps 2012. - 9781467349413 ; , s. 653-657
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a novel framework to enhance the throughput in a single-cell multiuser multiple-input multiple-output (MU-MIMO) system via adaptive base station (BS) antenna tilting. The key idea is to partition the cell into so-called vertical regions and to apply one out of a finite number of tilt and vertical half-power beamwidth (HPBW) pairs at the BS when serving each vertical region. This strategy results in an increased average received signal-to-noise ratio (SNR) over the coverage area. A scheduler is then employed to schedule the transmission to one of the vertical regions at each time-slot with the objective to maximize a suitable utility function of users' achievable throughput. MU-MIMO zero-forcing beamforming in the horizontal plane is used at the BS to serve the users in each vertical region. Simulation results show that the proposed adaptive BS tilting scheme is a promising approach to provide a noticeable throughput gain compared to a conventional scheme employing a fixed tilt at the BS. The proposed framework also achieves a superior performance-complexity tradeoff compared to a conventional system in which the tilt can be adapted to the location of the served users at each time-slot.
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| 4. |
- Tombaz, Sibel, et al.
(författare)
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Impact of Densification on Energy Efficiency in Wireless Access Networks
- 2012
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Ingår i: Globecom Workshops (GC Wkshps), 2012 IEEE. - : IEEE. - 9781467349413 ; , s. 57-62
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Konferensbidrag (refereegranskat)abstract
- Mobile communication networks alone consume 0.5 percent of the global energy today. Rapidly growing demand for capacity will further increase the energy consumption. Thus, improving energy efficiency has recently gained great interest within the research community not only for environmental awareness but also to lower the operational cost of network operators. Base station deployment strategy is one of the key challenges to be addressed for fulfilling the future capacity demand in an energy efficient manner. In this paper, we investigate the relationship between energy efficiency and densification with regard to network capacity requirement. To this end, we refine the base station power consumption model such that the parameters are determined by the maximum transmit power and develop a simple analytical framework to derive the optimum transmit power that maximizes energy efficiency for a certain capacity target. Our framework takes into account interference, noise and backhaul power consumption. Numerical results show that deployment of smaller cells significantly reduces the base station transmit power, and thus shifts the key elements of energy consumption to idling and backhauling power. Network densification can only be justified when capacity expansion is anticipated.
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| 5. |
- Vanin, Evgenii V.
(författare)
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Analytical model for optical wireless OFDM system with digital signal restoration
- 2012
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Ingår i: 2012 IEEE Globecom Workshops, GC Wkshps 2012. - 9781467349413 ; , s. 1213-1218
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Konferensbidrag (refereegranskat)abstract
- An analytical model for performance evaluation of the optical wireless communication (OWC) system employing orthogonal frequency division multiplexing (OFDM) with deliberate signal clipping and digital signal restoration is developed. The deliberate digital baseband clipping is introduced in the system transmitter in order to reduce a high peak-to-average power ratio (PAPR) of the OFDM signal and achieve an optimum modulation index of the intensity-modulated (IM) optical signal. In the system receiver a post-detection digital signal restoration is applied in an iterative manner in order to compensate for the effect of clipping noise and improve the system performance. It is emphasized that at the operation of decoding in the process of iterative signal restoration the main mechanism limiting the system performance at small clipping levels of the signal is introduced.
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| 6. |
- Yutao, Sui, 1984, et al.
(författare)
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Performance Comparison of Fixed and Moving Relays under Co-channel Interference
- 2012
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Ingår i: 2012 IEEE Globecom Workshops, GC Wkshps 2012; Anaheim, CA; United States; 3 December 2012 through 7 December 2012. - 9781467349413 ; , s. 574-579
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study and compare the outage probability (OP) of a vehicular user of dual-hop moving relay node (MRN) assisted transmission, dual-hop transmission assisted by a fixed relay node (FRN), as well as of the baseline single-hop direct transmission under of co-channel interference. For an accurate comparison, we numerically optimize the FRN position which minimizes the average vehicular user OP. When vehicular penetration loss is moderate to high, MRN assisted transmission is shown to greatly outperform transmission assisted by an FRN as well as direct transmission. Hence the use of MRNs is very promising for improving the quality-of-service of vehicular users for future mobile communication systems.
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