245 research outputs found
A Novel Transmission Scheme for the -user Broadcast Channel with Delayed CSIT
The state-dependent -user memoryless Broadcast Channel~(BC) with state
feedback is investigated. We propose a novel transmission scheme and derive its
corresponding achievable rate region, which, compared to some general schemes
that deal with feedback, has the advantage of being relatively simple and thus
is easy to evaluate. In particular, it is shown that the capacity region of the
symmetric erasure BC with an arbitrary input alphabet size is achievable with
the proposed scheme. For the fading Gaussian BC, we derive a symmetric
achievable rate as a function of the signal-to-noise ratio~(SNR) and a small
set of parameters. Besides achieving the optimal degrees of freedom at high
SNR, the proposed scheme is shown, through numerical results, to outperform
existing schemes from the literature in the finite SNR regime.Comment: 30 pages, 3 figures, submitted to IEEE Transactions on Wireless
Communications (revised version
Retroactive Anti-Jamming for MISO Broadcast Channels
Jamming attacks can significantly impact the performance of wireless
communication systems. In addition to reducing the capacity, such attacks may
lead to insurmountable overhead in terms of re-transmissions and increased
power consumption. In this paper, we consider the multiple-input single-output
(MISO) broadcast channel (BC) in the presence of a jamming attack in which a
subset of the receivers can be jammed at any given time. Further,
countermeasures for mitigating the effects of such jamming attacks are
presented. The effectiveness of these anti-jamming countermeasures is
quantified in terms of the degrees-of-freedom (DoF) of the MISO BC under
various assumptions regarding the availability of the channel state information
(CSIT) and the jammer state information at the transmitter (JSIT). The main
contribution of this paper is the characterization of the DoF region of the two
user MISO BC under various assumptions on the availability of CSIT and JSIT.
Partial extensions to the multi-user broadcast channels are also presented.Comment: submitted to IEEE Transactions on Information Theor
On the Degrees-of-freedom of the 3-user MISO Broadcast Channel with Hybrid CSIT
The 3-user multiple-input single-output (MISO) broadcast channel (BC) with
hybrid channel state information at the transmitter (CSIT) is considered. In
this framework, there is perfect and instantaneous CSIT from a subset of users
and delayed CSIT from the remaining users. We present new results on the
degrees of freedom (DoF) of the 3-user MISO BC with hybrid CSIT. In particular,
for the case of 2 transmit antennas, we show that with perfect CSIT from one
user and delayed CSIT from the remaining two users, the optimal DoF is 5/3. For
the case of 3 transmit antennas and the same hybrid CSIT setting, it is shown
that a higher DoF of 9/5 is achievable and this result improves upon the best
known bound. Furthermore, with 3 transmit antennas, and the hybrid CSIT setting
in which there is perfect CSIT from two users and delayed CSIT from the third
one, a novel scheme is presented which achieves 9/4 DoF. Our results also
reveal new insights on how to utilize hybrid channel knowledge for multi-user
scenarios
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