16 research outputs found
Performance characterization and transmission schemes for instantly decodable network coding in wireless broadcast
We consider broadcasting a block of packets to multiple wireless receivers under random packet erasures using
instantly decodable network coding (IDNC). The sender first broadcasts each packet uncoded once, then generates
coded packets according to receivers’ feedback about their missing packets. We focus on strict IDNC (S-IDNC), where
each coded packet includes at most one missing packet of every receiver. But, we will also study its relation with
generalized IDNC (G-IDNC), where this condition is relaxed. We characterize two fundamental performance limits of
S-IDNC: (1) the number of transmissions to complete the broadcast, which measures throughput and (2) average
packet decoding delay, which measures how fast each packet is decoded at each receiver on average. We derive a
closed-form expression for the expected minimum number of transmissions in terms of the number of packets and
receivers and the erasure probability. We prove that it is NP-hard to minimize the average packet decoding delay of
S-IDNC. We also prove that the graph models of S- and G-IDNC share the same chromatic number. Next, we design
efficient S-IDNC transmission schemes and coding algorithms with full/intermittent receiver feedback. We present
simulation results to corroborate the developed theory and compare our schemes with existing ones
Instantly Decodable Network Coding: From Point to Multi-Point to Device-to-Device Communications
The network coding paradigm enhances transmission efficiency by
combining information
flows and has drawn significant attention in information theory,
networking, communications
and data storage. Instantly decodable network coding (IDNC), a
subclass of network coding,
has demonstrated its ability to improve the quality of service of
time critical applications
thanks to its attractive properties, namely the throughput
enhancement, delay reduction,
simple XOR-based encoding and decoding, and small coefficient
overhead. Nonetheless, for
point to multi-point (PMP) networks, IDNC cannot guarantee the
decoding of a specific new
packet at individual devices in each transmission. Furthermore,
for device-to-device (D2D)
networks, the transmitting devices may possess only a subset of
packets, which can be used
to form coded packets. These challenges require the optimization
of IDNC algorithms to be
suitable for different application requirements and network
configurations.
In this thesis, we first study a scalable live video broadcast
over a wireless PMP network,
where the devices receive video packets from a base station. Such
layered live video has a
hard deadline and imposes a decoding order on the video layers.
We design two prioritized
IDNC algorithms that provide a high level of priority to the most
important video layer
before considering additional video layers in coding decisions.
These prioritized algorithms
are shown to increase the number of decoded video layers at the
devices compared to the
existing network coding schemes.
We then study video distribution over a partially connected D2D
network, where a group
of devices cooperate with each other to recover their missing
video content. We introduce
a cooperation aware IDNC graph that defines all feasible coding
and transmission conflictfree
decisions. Using this graph, we propose an IDNC solution that
avoids coding and
transmission conflicts, and meets the hard deadline for high
importance video packets. It is
demonstrated that the proposed solution delivers an improved
video quality to the devices
compared to the video and cooperation oblivious coding schemes.
We also consider a heterogeneous network wherein devices use two
wireless interfaces to
receive packets from the base station and another device
concurrently. For such network,
we are interested in applications with reliable in-order packet
delivery requirements. We
represent all feasible coding opportunities and conflict-free
transmissions using a dual interface
IDNC graph. We select a maximal independent set over the graph by
considering dual
interfaces of individual devices, in-order delivery requirements
of packets and lossy channel
conditions. This graph based solution is shown to reduce the
in-order delivery delay
compared to the existing network coding schemes.
Finally, we consider a D2D network with a group of devices
experiencing heterogeneous
channel capacities. For such cooperative scenarios, we address
the problem of minimizing
the completion time required for recovering all missing packets
at the devices using IDNC
and physical layer rate adaptation. Our proposed IDNC algorithm
balances between the
adopted transmission rate and the number of targeted devices that
can successfully receive
the transmitted packet. We show that the proposed rate aware IDNC
algorithm reduces the
completion time compared to the rate oblivious coding scheme