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Intra- and Inter-Session Network Coding in Wireless Networks
In this paper, we are interested in improving the performance of constructive
network coding schemes in lossy wireless environments.We propose I2NC - a
cross-layer approach that combines inter-session and intra-session network
coding and has two strengths. First, the error-correcting capabilities of
intra-session network coding make our scheme resilient to loss. Second,
redundancy allows intermediate nodes to operate without knowledge of the
decoding buffers of their neighbors. Based only on the knowledge of the loss
rates on the direct and overhearing links, intermediate nodes can make
decisions for both intra-session (i.e., how much redundancy to add in each
flow) and inter-session (i.e., what percentage of flows to code together)
coding. Our approach is grounded on a network utility maximization (NUM)
formulation of the problem. We propose two practical schemes, I2NC-state and
I2NC-stateless, which mimic the structure of the NUM optimal solution. We also
address the interaction of our approach with the transport layer. We
demonstrate the benefits of our schemes through simulations
Modeling Network Coded TCP Throughput: A Simple Model and its Validation
We analyze the performance of TCP and TCP with network coding (TCP/NC) in
lossy wireless networks. We build upon the simple framework introduced by
Padhye et al. and characterize the throughput behavior of classical TCP as well
as TCP/NC as a function of erasure rate, round-trip time, maximum window size,
and duration of the connection. Our analytical results show that network coding
masks erasures and losses from TCP, thus preventing TCP's performance
degradation in lossy networks, such as wireless networks. It is further seen
that TCP/NC has significant throughput gains over TCP. In addition, we simulate
TCP and TCP/NC to verify our analysis of the average throughput and the window
evolution. Our analysis and simulation results show very close concordance and
support that TCP/NC is robust against erasures. TCP/NC is not only able to
increase its window size faster but also to maintain a large window size
despite losses within the network, whereas TCP experiences window closing
essentially because losses are mistakenly attributed to congestion.Comment: 9 pages, 12 figures, 1 table, submitted to IEEE INFOCOM 201
Network coding meets TCP
We propose a mechanism that incorporates network coding into TCP with only
minor changes to the protocol stack, thereby allowing incremental deployment.
In our scheme, the source transmits random linear combinations of packets
currently in the congestion window. At the heart of our scheme is a new
interpretation of ACKs - the sink acknowledges every degree of freedom (i.e., a
linear combination that reveals one unit of new information) even if it does
not reveal an original packet immediately. Such ACKs enable a TCP-like
sliding-window approach to network coding. Our scheme has the nice property
that packet losses are essentially masked from the congestion control
algorithm. Our algorithm therefore reacts to packet drops in a smooth manner,
resulting in a novel and effective approach for congestion control over
networks involving lossy links such as wireless links. Our experiments show
that our algorithm achieves higher throughput compared to TCP in the presence
of lossy wireless links. We also establish the soundness and fairness
properties of our algorithm.Comment: 9 pages, 9 figures, submitted to IEEE INFOCOM 200
milliProxy: a TCP Proxy Architecture for 5G mmWave Cellular Systems
TCP is the most widely used transport protocol in the internet. However, it
offers suboptimal performance when operating over high bandwidth mmWave links.
The main issues introduced by communications at such high frequencies are (i)
the sensitivity to blockage and (ii) the high bandwidth fluctuations due to
Line of Sight (LOS) to Non Line of Sight (NLOS) transitions and vice versa. In
particular, TCP has an abstract view of the end-to-end connection, which does
not properly capture the dynamics of the wireless mmWave link. The consequence
is a suboptimal utilization of the available resources. In this paper we
propose a TCP proxy architecture that improves the performance of TCP flows
without any modification at the remote sender side. The proxy is installed in
the Radio Access Network, and exploits information available at the gNB in
order to maximize throughput and minimize latency.Comment: 7 pages, 6 figures, 2 tables, presented at the 2017 51st Asilomar
Conference on Signals, Systems and Computers, Pacific Grove, CA, 201
eCMT-SCTP: Improving Performance of Multipath SCTP with Erasure Coding Over Lossy Links
Performance of transport protocols on lossy links is a well-researched topic, however there are only a few proposals making use of the opportunities of erasure coding within the multipath transport protocol context. In this paper, we investigate performance improvements of multipath CMT-SCTP with the novel integration of the on-the-fly erasure code within congestion control and reliability mechanisms. Our contributions include: integration of transport protocol and erasure codes with regards to congestion control; proposal for a variable retransmission delay parameter (aRTX) adjustment; performance evaluation of CMT-SCTP with erasure coding with simulations. We have implemented the explicit congestion notification (ECN) and erasure coding schemes in NS-2, evaluated and demonstrated results of improvement both for application goodput and decline of spurious retransmission. Our results show that we can achieve from 10% to 80% improvements in goodput under lossy network conditions without a significant penalty and minimal overhead due to the encoding-decoding process
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