5,386 research outputs found
Delay Estimation and Fast Iterative Scheduling Policies for LTE Uplink
We consider the allocation of spectral and power resources to the mobiles
(i.e., user equipment (UE)) in a cell every subframe (1 ms) for the Long Term
Evolution (LTE) orthogonal frequency division multiple access (OFDMA) cellular
network. To enable scheduling based on packet delays, we design a novel
mechanism for inferring the packet delays approximately from the buffer status
reports (BSR) transmitted by the UEs; the BSR reports only contain queue length
information. We then consider a constrained optimization problem with a concave
objective function - schedulers such as those based on utility maximization,
maximum weight scheduling, and recent results on iterative scheduling for small
queue/delay follow as special cases. In particular, the construction of the
non-differentiable objective function based on packet delays is novel. We model
constraints on bandwidth, peak transmit power at the UE, and the transmit power
spectral density (PSD) at the UE due to fractional power control. When
frequency diversity doesn't exist or is not exploited at a fast time-scale, we
use subgradient analysis to construct an O(N log L) (per iteration with small
number of iterations) algorithm to compute the optimal resource allocation for
N users and L points of non-differentiability in the objective function. For a
frequency diversity scheduler with M sub-bands, the corre- sponding complexity
per iteration is essentially O(N(M^2+L^2)). Unlike previous iterative policies
based on delay/queue, in our approach the complexity of scheduling can be
reduced when the coherence bandwidth is larger. Through detailed system
simulations (based on NGMN and 3GPP evaluation methodology) which model H-ARQ,
finite resource grants per sub-frame, deployment, realistic traffic, power
limitations, interference, and channel fading, we demonstrate the effectiveness
of our schemes for LTE
Joint Data Scheduling and FEC Coding for Multihomed Wireless Video Delivery
This paper studies the problem of mobile video delivery in heterogenous
wireless networks from a server to multihomed device. Most existing works only
consider delivering video streaming on single path which bandwidth is limited
causing ultimate video transmission rate. To solve this live video streaming
transmission bottleneck problem, we propose a novel solution named Joint Data
Allocation and Fountain Coding (JDAFC) method that contain below characters:
(1) path selection, (2) dynamic data allocation, and (3) fountain coding. We
evaluate the performance of JDAFC by simulation experiments using Exata and
JVSM and compare it with some reference solutions. Experimental results
represent that JDAFC outperforms the competing solutions in improving the video
peak signal-to-noise ratio as well as reducing the end-to-end delay.Comment: 6 page
Joint Source-Channel Coding for Real-Time Video Transmission to Multi-homed Mobile Terminals
This study focuses on the mobile video delivery from a video server to a
multi-homed client with a network of heterogeneous wireless. Joint
Source-Channel Coding is effectively used to transmit video over
bandwidth-limited, noisy wireless networks. But most existing JSCC methods only
consider single path video transmission of the server and the client network.
The problem will become more complicated when consider multi-path video
transmission, because involving low-bandwidth, high-drop-rate or high-latency
wireless network will only reduce the video quality. To solve this critical
problem, we propose a novel Path Adaption JSCC (PA-JSCC) method that contain
below characters: (1) path adaption, and (2) dynamic rate allocation. We use
Exata to evaluate the performance of PA-JSCC and Experiment show that PA-JSCC
has a good results in terms of PSNR (Peak Signal-to-Noise Ratio).Comment: 5 pages. arXiv admin note: text overlap with arXiv:1406.7054 by other
author
Scalable Peer-to-Peer Streaming for Live Entertainment Content
We present a system for streaming live entertainment content over the Internet originating from a single source to a scalable number of consumers without resorting to centralized or provider-provisioned resources. The system creates a peer-to-peer overlay network, which attempts to optimize use of existing capacity to ensure quality of service, delivering low startup delay and lag in playout of the live content. There are three main aspects of our solution: first, a swarming mechanism that constructs an overlay topology for minimizing propagation delays from the source to end consumers; second, a distributed overlay anycast system that uses a location-based search algorithm for peers to quickly find the closest peers in a given stream; and finally, a novel incentive mechanism that encourages peers to donate capacity even when the user is not actively consuming content
A Novel Play-out Algorithm for HTTP Adaptive Streaming
In the paper, we proposed a novel algorithm dedicated to adaptive video
streaming based on HTTP. The algorithm employs a hybrid play-out strategy which
combines two popular approaches: an estimation of network bandwidth and a
control of a player buffer. The proposed algorithm was implemented in two
versions which differ in the method of handling fluctuations of network
throughput.
The proposed hybrid algorithm was evaluated against solutions which base
their play-out strategy purely on bandwidth or buffer level assessment. The
comparison was performed in an environment which emulated two systems: a Wi-Fi
network with a single immobile node and HSPA (High Speed Packet Access) network
with a mobile node. The evaluation shows that the hybrid approach in most cases
achieves better results compared to its competitors, being able to stream the
video more smoothly without unnecessary bit-rate switches. However, in certain
network conditions, this score is traded for a worse throughput utilisation
compared to other play-out strategies
Distortion-Aware Concurrent Multipath Transfer for Mobile Video Streaming in Heterogeneous Wireless Networks
The massive proliferation of wireless infrastructures with complementary
characteristics prompts the bandwidth aggregation for Concurrent Multipath
Transfer (CMT) over heterogeneous access networks. Stream Control Transmission
Protocol (SCTP) is the standard transport-layer solution to enable CMT in
multihomed communication environments. However, delivering high-quality
streaming video with the existing CMT solutions still remains problematic due
to the stringent QoS (Quality of Service) requirements and path asymmetry in
heterogeneous wireless networks. In this paper, we advance the state of the art
by introducing video distortion into the decision process of multipath data
transfer. The proposed Distortion-Aware Concurrent Multipath Transfer (CMT-DA)
solution includes three phases: 1) per-path status estimation and congestion
control; 2) quality-optimal video flow rate allocation; 3) delay and loss
controlled data retransmission. The term `flow rate allocation' indicates
dynamically picking appropriate access networks and assigning the transmission
rates. We analytically formulate the data distribution over multiple
communication paths to minimize the end-to-end video distortion and derive the
solution based on the utility maximization theory. The performance of the
proposed CMT-DA is evaluated through extensive semi-physical emulations in
Exata involving H.264 video streaming. Experimental results show that CMT-DA
outperforms the reference schemes in terms of video PSNR (Peak Signal-to-Noise
Ratio), goodput, and inter-packet delay.Comment: This paper has already accepted for publication in IEEE Transactions
on Mobile Computing on Jun, 23rd, 201
Delay-Aware Coded Caching for Mobile Users
In this work, we study the trade-off between the cache capacity and the user
delay for a cooperative Small Base Station (SBS) coded caching system with
mobile users. First, a delay-aware coded caching policy, which takes into
account the popularity of the files and the maximum re-buffering delay to
minimize the average rebuffering delay of a mobile user under a given cache
capacity constraint is introduced. Subsequently, we address a scenario where
some files are served by the macro-cell base station (MBS) when the cache
capacity of the SBSs is not sufficient to store all the files in the library.
For this scenario, we develop a coded caching policy that minimizes the average
amount of data served by the MBS under an average re-buffering delay
constraint
Temporal Reachability Graphs
While a natural fit for modeling and understanding mobile networks,
time-varying graphs remain poorly understood. Indeed, many of the usual
concepts of static graphs have no obvious counterpart in time-varying ones. In
this paper, we introduce the notion of temporal reachability graphs. A
(tau,delta)-reachability graph} is a time-varying directed graph derived from
an existing connectivity graph. An edge exists from one node to another in the
reachability graph at time t if there exists a journey (i.e., a spatiotemporal
path) in the connectivity graph from the first node to the second, leaving
after t, with a positive edge traversal time tau, and arriving within a maximum
delay delta. We make three contributions. First, we develop the theoretical
framework around temporal reachability graphs. Second, we harness our
theoretical findings to propose an algorithm for their efficient computation.
Finally, we demonstrate the analytic power of the temporal reachability graph
concept by applying it to synthetic and real-life datasets. On top of defining
clear upper bounds on communication capabilities, reachability graphs highlight
asymmetric communication opportunities and offloading potential.Comment: In proceedings ACM Mobicom 201
Distributed Overlay Anycast Table using Space filling curves
In this paper we present the \emph{Distributed Overlay Anycast Table}, a
structured overlay that implements application-layer anycast, allowing the
discovery of the closest host that is a member of a given group. One
application is in locality-aware peer-to-peer networks, where peers need to
discover low-latency peers participating in the distribution of a particular
file or stream. The DOAT makes use of network delay coordinates and a space
filling curve to achieve locality-aware routing across the overlay, and Bloom
filters to aggregate group identifiers. The solution is designed to optimise
both accuracy and query time, which are essential for real-time applications.
We simulated DOAT using both random and realistic node distributions. The
results show that accuracy is high and query time is low.Comment: 7 pages, 4 figure
Error Resilient Multipath Video Delivery on Wireless Overlay Networks
Real time applications delivering multimedia data over wireless networks still pose many challenges due to high throughput and stringent delay requirements. Overlay networks with multipath transmission is the promising solution to address the above problems. But in wireless networks the maintenance of overlay networks induce additional overheads affecting the bulky and delay sensitive delivery of multimedia data. To minimize the overheads, this work introduces the Error Compensated Data Distribution Model (ECDD) that aids in reducing end to end delays and overheads arising from packet retransmissions. The ECDD adopts mTreebone algorithm to identify the unstable wireless nodes and construct overlay tree. The overlay tree is further split to support multipath transmissions. A sub packetization mechanism is adopted for multipath video data delivery in the ECDD. A forward error correction mechanism and sub-packet retransmission techniques adopted in ECDD enables to reduce the overhead and end to end delay. The simulation results presented in this paper prove that the ECDD model proposed achieves lower end to end delay and outperforms the existing models in place. Retransmission requests are minimized by about 52.27% and bit errors are reduced by about 23.93% than Sub-Packet based Multipath Load Distribution
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