220 research outputs found
Cache-Aided Non-Orthogonal Multiple Access
In this paper, we propose a novel joint caching and non-orthogonal multiple
access (NOMA) scheme to facilitate advanced downlink transmission for next
generation cellular networks. In addition to reaping the conventional
advantages of caching and NOMA transmission, the proposed cache-aided NOMA
scheme also exploits cached data for interference cancellation which is not
possible with separate caching and NOMA transmission designs. Furthermore, as
caching can help to reduce the residual interference power, several decoding
orders are feasible at the receivers, and these decoding orders can be flexibly
selected for performance optimization. We characterize the achievable rate
region of cache-aided NOMA and investigate its benefits for minimizing the time
required to complete video file delivery. Our simulation results reveal that,
compared to several baseline schemes, the proposed cache-aided NOMA scheme
significantly expands the achievable rate region for downlink transmission,
which translates into substantially reduced file delivery times.Comment: Accepted for presentation at IEEE ICC 201
Cache-Aided Non-Orthogonal Multiple Access: The Two-User Case
In this paper, we propose a cache-aided non-orthogonal multiple access (NOMA)
scheme for spectrally efficient downlink transmission. The proposed scheme not
only reaps the benefits associated with NOMA and caching, but also exploits the
data cached at the users for interference cancellation. As a consequence,
caching can help to reduce the residual interference power, making multiple
decoding orders at the users feasible. The resulting flexibility in decoding
can be exploited for improved NOMA detection. We characterize the achievable
rate region of cache-aided NOMA and derive the Pareto optimal rate tuples
forming the boundary of the rate region. Moreover, we optimize cache-aided NOMA
for minimization of the time required for completing file delivery. The optimal
decoding order and the optimal transmit power and rate allocation are derived
as functions of the cache status, the file sizes, and the channel conditions.
Simulation results confirm that, compared to several baseline schemes, the
proposed cache-aided NOMA scheme significantly expands the achievable rate
region and increases the sum rate for downlink transmission, which translates
into substantially reduced file delivery times.Comment: Accepted for publication in IEEE J. Sel. Topics Signal Process. arXiv
admin note: text overlap with arXiv:1712.0955
Cache-Aided Non-Orthogonal Multiple Access for 5G-Enabled Vehicular Networks
The increasing demand for rich multimedia services and the emergence of the
Internet-of-Things (IoT) pose challenging requirements for the next generation
vehicular networks. Such challenges are largely related to high spectral
efficiency and low latency requirements in the context of massive content
delivery and increased connectivity. In this respect, caching and
non-orthogonal multiple access (NOMA) paradigms have been recently proposed as
potential solutions to effectively address some of these key challenges. In the
present contribution, we introduce cache-aided NOMA as an enabling technology
for vehicular networks. In this context, we first consider the full file
caching case, where each vehicle caches and requests entire files using the
NOMA principle. Without loss of generality, we consider a two-user vehicular
network communication scenario under double Nakagami fading conditions and
propose an optimum power allocation policy. To this end, an optimization
problem that maximizes the overall probability of successful decoding of files
at each vehicle is formulated and solved. Furthermore, we consider the case of
split file caching, where each file is divided into two parts. A joint power
allocation optimization problem is formulated, where power allocation across
vehicles and cached split files is investigated. The offered analytic results
are corroborated by extensive results from computer simulations and interesting
insights are developed. Indicatively, it is shown that the proposed
caching-aided NOMA outperforms the conventional NOMA technique.Comment: Accepted for publication in IEEE Transactions on Vehicular Technolog
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