20 research outputs found
Wireless Communications in the Era of Big Data
The rapidly growing wave of wireless data service is pushing against the
boundary of our communication network's processing power. The pervasive and
exponentially increasing data traffic present imminent challenges to all the
aspects of the wireless system design, such as spectrum efficiency, computing
capabilities and fronthaul/backhaul link capacity. In this article, we discuss
the challenges and opportunities in the design of scalable wireless systems to
embrace such a "bigdata" era. On one hand, we review the state-of-the-art
networking architectures and signal processing techniques adaptable for
managing the bigdata traffic in wireless networks. On the other hand, instead
of viewing mobile bigdata as a unwanted burden, we introduce methods to
capitalize from the vast data traffic, for building a bigdata-aware wireless
network with better wireless service quality and new mobile applications. We
highlight several promising future research directions for wireless
communications in the mobile bigdata era.Comment: This article is accepted and to appear in IEEE Communications
Magazin
Distributed Information Bottleneck for a Primitive Gaussian Diamond MIMO Channel
This paper considers the distributed information bottleneck (D-IB) problem for a primitive Gaussian diamond channel with two relays and MIMO Rayleigh fading. The channel state is an independent and identically distributed (i.i.d.) process known at the relays but unknown to the destination. The relays are oblivious, i.e., they are unaware of the codebook and treat the transmitted signal as a random process with known statistics. The bottleneck constraints prevent the relays to communicate the channel state information (CSI) perfectly to the destination. To evaluate the bottleneck rate, we provide an upper bound by assuming that the destination node knows the CSI and the relays can cooperate with each other, and also two achievable schemes with simple symbol-by-symbol relay processing and compression. Numerical results show that the lower bounds obtained by the proposed achievable schemes can come close to the upper bound on a wide range of relevant system parameters
Joint Fronthaul Load Balancing and Computation Resource Allocation in Cell-Free User-Centric Massive MIMO Networks
We consider scalable cell-free massive multiple-input multiple-output
networks under an open radio access network paradigm comprising user equipments
(UEs), radio units (RUs), and decentralized processing units (DUs). UEs are
served by dynamically allocated user-centric clusters of RUs. The corresponding
cluster processors (implementing the physical layer for each user) are hosted
by the DUs as software-defined virtual network functions. Unlike the current
literature, mainly focused on the characterization of the user rates under
unrestricted fronthaul communication and computation, in this work we
explicitly take into account the fronthaul topology, the limited fronthaul
communication capacity, and computation constraints at the DUs. In particular,
we systematically address the new problem of joint fronthaul load balancing and
allocation of the computation resource. As a consequence of our new
optimization framework, we present representative numerical results
highlighting the existence of an optimal number of quantization bits in the
analog-to-digital conversion at the RUs.Comment: 13 pages, 5 figures, submitted to IEEE Transactions on Wireless
Communication
Distributed MIMO broadcasting: Reverse compute-and-forward and signal-space alignment
© 2002-2012 IEEE. We study a downlink distributed MIMO system where a central unit (CU) broadcasts messages to K′ users through K distributed BSS. The CU is connected to the BSS via K independent rate-constrained fronthaul (FH) links. The distributed BSS collectively serve the users through the air. We propose a new network coding based distributed MIMO broadcasting scheme, using reverse compute-and-forward and signal-space alignment. At the CU, a network coding generator matrix is employed for pre network coding of the users' messages. The network coded messages are forwarded to the BSS, where the FH rate-constraint determines the actual number of network-coded messages forwarded to the BSS. At the BSS, linear precoding matrices are designed to create a number of bins, each containing a bunch of spatial streams with aligned signal-spaces. At each user, post physical-layer network coding is employed to compute linear combinations over the NC messages with respect to the bins, which reverses the prenetwork coding and recovers the desired messages. We derive an achievable rate of the proposed scheme based on the existence of NC generator matrix, signal-space alignment precoding matrices, and nested lattice codes. Improved rate and degrees of freedom over existing interference alignment and compress-and-forward schemes are shown. Numerical results demonstrate the performance improvement, e.g., by as much as 70% increase in throughput over benchmark schemes
Integer-forcing architectures for uplink cloud radio access networks
Consider an uplink cloud radio access network where users are observed simultaneously by several base stations, each with a rate-limited link to a central processor, which wishes to decode all transmitted messages. Recent efforts have demonstrated the advantages of compression-based strategies that send quantized channel observations to the central processor, rather than attempt local decoding. We study the setting where channel state information is not available at the transmitters, but known fully or partially at the base stations. We propose an end-to-end integer forcing framework for compression-based uplink cloud radio access, and show that it operates within a constant gap from the optimal outage probability if channel state information is fully available at the base stations.We demonstrate via simulations that our framework is competitive with state-of-the-art Wyner-Ziv-based strategies.Accepted manuscrip