11,595 research outputs found
Energy-efficient wireless communication
In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters
Reliable and Low-Latency Fronthaul for Tactile Internet Applications
With the emergence of Cloud-RAN as one of the dominant architectural
solutions for next-generation mobile networks, the reliability and latency on
the fronthaul (FH) segment become critical performance metrics for applications
such as the Tactile Internet. Ensuring FH performance is further complicated by
the switch from point-to-point dedicated FH links to packet-based multi-hop FH
networks. This change is largely justified by the fact that packet-based
fronthauling allows the deployment of FH networks on the existing Ethernet
infrastructure. This paper proposes to improve reliability and latency of
packet-based fronthauling by means of multi-path diversity and erasure coding
of the MAC frames transported by the FH network. Under a probabilistic model
that assumes a single service, the average latency required to obtain reliable
FH transport and the reliability-latency trade-off are first investigated. The
analytical results are then validated and complemented by a numerical study
that accounts for the coexistence of enhanced Mobile BroadBand (eMBB) and
Ultra-Reliable Low-Latency (URLLC) services in 5G networks by comparing
orthogonal and non-orthogonal sharing of FH resources.Comment: 11pages, 13 figures, 3 bio photo
In-Order Delivery Delay of Transport Layer Coding
A large number of streaming applications use reliable transport protocols
such as TCP to deliver content over the Internet. However, head-of-line
blocking due to packet loss recovery can often result in unwanted behavior and
poor application layer performance. Transport layer coding can help mitigate
this issue by helping to recover from lost packets without waiting for
retransmissions. We consider the use of an on-line network code that inserts
coded packets at strategic locations within the underlying packet stream. If
retransmissions are necessary, additional coding packets are transmitted to
ensure the receiver's ability to decode. An analysis of this scheme is provided
that helps determine both the expected in-order packet delivery delay and its
variance. Numerical results are then used to determine when and how many coded
packets should be inserted into the packet stream, in addition to determining
the trade-offs between reducing the in-order delay and the achievable rate. The
analytical results are finally compared with experimental results to provide
insight into how to minimize the delay of existing transport layer protocols
Run-time Energy Management for Mobiles
Due to limited energy resources, mobile computing requires an energy-efficient a rchitecture. The dynamic nature of a mobile environment demands an architecture that allows adapting to (quickly) changing conditions. The mobile has to adapt d ynamically to new circumstances in the best suitable manner. The hardware and so ftware architecture should be able to support such adaptability and minimize the energy consumption by making resource allocation decisions at run-time. To make these decisions effective, a tradeoff has to be made between computation , communication and initialization costs (both time and energy). This paper describes our approach to construct a model that supports taking such decisions
Cross-layer based erasure code to reduce the 802.11 performance anomaly : when FEC meets ARF
Wireless networks have been widely accepted and deployed in our world nowadays. Consumers are now accustomed to wireless connectivity in their daily life due to the pervasive- ness of the 802.11b/g and wireless LAN standards. Specially, the emergence of the next evolution of Wi-Fi technology known as 802.11n is pushing a new revolution on personal wireless communication. However, in the context of WLAN, although multiple novel wireless access technologies have been proposed and developed to offer high bandwidth and guarantee quality of transmission, some deficiencies still remain due to the original design of WLAN-MAC layer. In particular, the performance anomaly of 802.11 is a serious issue which induces a potentially dramatic reduction of the global bandwidth when one or several mobile nodes downgrade their transmission rates following the signal degradation. In this paper, we study how the use of adaptive erasure code as a replacement of the Auto Rate Feedback mechanism can help to mitigate this performance anomaly issue. Preliminary study shows a global increase of the goodput delivered to mobile hosts attached to an access point
Achievable DoF-delay trade-offs for the K-user MIMO interference channel with delayed CSIT
©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any
current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new
collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other
works.The degrees of freedom (DoFs) of the K-user multiple-input multiple-output (MIMO) interference channel are studied when perfect, but delayed channel state information is available at the transmitter side (delayed CSIT). Recent works have proposed schemes improving the DoF knowledge of the interference channel, but at the cost of developing transmission involving many channel uses (long delay), thus increasing the complexity at both transmitter and receiver side. This paper proposes three linear precoding strategies, limited to at most three phases, based on the concept of interference alignment, and built upon three main ingredients: delayed CSIT precoding, user scheduling, and redundancy transmission. In this respect, the interference alignment is realized by exploiting delayed CSIT to align the interference at the non-intended receivers along the space-time domain. Moreover, a new framework is proposed where the number of transmitted symbols and duration of the phases is obtained as the solution of a maximization problem, and enabling the introduction of complexity constraints, which allows deriving the achievable DoF as a function of the transmission delay, i.e., the achievable DoF-delay trade-off. Finally, the latter part of this paper settles that the assumption of time-varying channels common along all the literature on delayed CSIT is indeed unnecessary.Peer ReviewedPostprint (author's final draft
- âŠ