15,513 research outputs found
Information Exchange Limits in Cooperative MIMO Networks
Concurrent presence of inter-cell and intra-cell interferences constitutes a
major impediment to reliable downlink transmission in multi-cell multiuser
networks. Harnessing such interferences largely hinges on two levels of
information exchange in the network: one from the users to the base-stations
(feedback) and the other one among the base-stations (cooperation). We
demonstrate that exchanging a finite number of bits across the network, in the
form of feedback and cooperation, is adequate for achieving the optimal
capacity scaling. We also show that the average level of information exchange
is independent of the number of users in the network. This level of information
exchange is considerably less than that required by the existing coordination
strategies which necessitate exchanging infinite bits across the network for
achieving the optimal sum-rate capacity scaling. The results provided rely on a
constructive proof.Comment: 35 pages, 5 figur
Joint Multi-Cell Resource Allocation Using Pure Binary-Integer Programming for LTE Uplink
Due to high system capacity requirement, 3GPP Long Term Evolution (LTE) is
likely to adopt frequency reuse factor 1 at the cost of suffering severe
inter-cell interference (ICI). One of combating ICI strategies is network
cooperation of resource allocation (RA). For LTE uplink RA, requiring all the
subcarriers to be allocated adjacently complicates the RA problem greatly. This
paper investigates the joint multi-cell RA problem for LTE uplink. We model the
uplink RA and ICI mitigation problem using pure binary-integer programming
(BIP), with integrative consideration of all users' channel state information
(CSI). The advantage of the pure BIP model is that it can be solved by
branch-and-bound search (BBS) algorithm or other BIP solving algorithms, rather
than resorting to exhaustive search. The system-level simulation results show
that it yields 14.83% and 22.13% gains over single-cell optimal RA in average
spectrum efficiency and 5th percentile of user throughput, respectively.Comment: Accepted to IEEE Vehicular Technology Conference (VTC Spring), Seoul,
Korea, May, 201
Analysis Framework for Opportunistic Spectrum OFDMA and its Application to the IEEE 802.22 Standard
We present an analytical model that enables throughput evaluation of
Opportunistic Spectrum Orthogonal Frequency Division Multiple Access (OS-OFDMA)
networks. The core feature of the model, based on a discrete time Markov chain,
is the consideration of different channel and subchannel allocation strategies
under different Primary and Secondary user types, traffic and priority levels.
The analytical model also assesses the impact of different spectrum sensing
strategies on the throughput of OS-OFDMA network. The analysis applies to the
IEEE 802.22 standard, to evaluate the impact of two-stage spectrum sensing
strategy and varying temporal activity of wireless microphones on the IEEE
802.22 throughput. Our study suggests that OS-OFDMA with subchannel notching
and channel bonding could provide almost ten times higher throughput compared
with the design without those options, when the activity and density of
wireless microphones is very high. Furthermore, we confirm that OS-OFDMA
implementation without subchannel notching, used in the IEEE 802.22, is able to
support real-time and non-real-time quality of service classes, provided that
wireless microphones temporal activity is moderate (with approximately one
wireless microphone per 3,000 inhabitants with light urban population density
and short duty cycles). Finally, two-stage spectrum sensing option improves
OS-OFDMA throughput, provided that the length of spectrum sensing at every
stage is optimized using our model
A Non-Cooperative Power Control Game in Delay-Constrained Multiple-Access Networks
A game-theoretic approach for studying power control in multiple-access
networks with transmission delay constraints is proposed. A non-cooperative
power control game is considered in which each user seeks to choose a transmit
power that maximizes its own utility while satisfying the user's delay
requirements. The utility function measures the number of reliable bits
transmitted per joule of energy and the user's delay constraint is modeled as
an upper bound on the delay outage probability. The Nash equilibrium for the
proposed game is derived, and its existence and uniqueness are proved. Using a
large-system analysis, explicit expressions for the utilities achieved at
equilibrium are obtained for the matched filter, decorrelating and minimum mean
square error multiuser detectors. The effects of delay constraints on the
users' utilities (in bits/Joule) and network capacity (i.e., the maximum number
of users that can be supported) are quantified.Comment: To apprear in the proceedings of the 2005 IEEE International
Symposium on Information Theory, Adelaide, Australia, September 4-9, 200
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