473 research outputs found
Joint Scheduling and ARQ for MU-MIMO Downlink in the Presence of Inter-Cell Interference
User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the
core of high rate data-oriented downlink schemes of the next-generation of
cellular systems (e.g., LTE-Advanced). Scheduling selects groups of users
according to their channels vector directions and SINR levels. However, when
scheduling is applied independently in each cell, the inter-cell interference
(ICI) power at each user receiver is not known in advance since it changes at
each new scheduling slot depending on the scheduling decisions of all
interfering base stations. In order to cope with this uncertainty, we consider
the joint operation of scheduling, MU-MIMO beamforming and Automatic Repeat
reQuest (ARQ). We develop a game-theoretic framework for this problem and build
on stochastic optimization techniques in order to find optimal scheduling and
ARQ schemes. Particularizing our framework to the case of "outage service
rates", we obtain a scheme based on adaptive variable-rate coding at the
physical layer, combined with ARQ at the Logical Link Control (ARQ-LLC). Then,
we present a novel scheme based on incremental redundancy Hybrid ARQ (HARQ)
that is able to achieve a throughput performance arbitrarily close to the
"genie-aided service rates", with no need for a genie that provides
non-causally the ICI power levels. The novel HARQ scheme is both easier to
implement and superior in performance with respect to the conventional
combination of adaptive variable-rate coding and ARQ-LLC.Comment: Submitted to IEEE Transactions on Communications, v2: small
correction
Multiuser MAC Schemes for High-Throughput IEEE 802.11n/ac WLANs
In the last decade, the Wireless Local Area Network (WLAN) market has been experiencing
an impressive growth that began with the broad acceptance of the IEEE 802.11 standard [1].
Given the widespread deployment of WLANs and the increasing requirements of multimedia
applications, the need for high capacity and enhanced reliability has become imperative.
Multiple-Input Multiple-Output (MIMO) technology and its single receiving antenna version,
MISO (Multiple-Input Single-Output (MISO), promise a signiÂżcant performance boost and
have been incorporated in the emerging IEEE 802.11n standard.Peer ReviewedPostprint (published version
- âŠ