6,489 research outputs found
Opportunistic Interference Mitigation Achieves Optimal Degrees-of-Freedom in Wireless Multi-cell Uplink Networks
We introduce an opportunistic interference mitigation (OIM) protocol, where a
user scheduling strategy is utilized in -cell uplink networks with
time-invariant channel coefficients and base stations (BSs) having
antennas. Each BS opportunistically selects a set of users who generate the
minimum interference to the other BSs. Two OIM protocols are shown according to
the number of simultaneously transmitting users per cell: opportunistic
interference nulling (OIN) and opportunistic interference alignment (OIA).
Then, their performance is analyzed in terms of degrees-of-freedom (DoFs). As
our main result, it is shown that DoFs are achievable under the OIN
protocol with selected users per cell, if the total number of users in
a cell scales at least as . Similarly, it turns out that
the OIA scheme with () selected users achieves DoFs, if scales
faster than . These results indicate that there exists a
trade-off between the achievable DoFs and the minimum required . By deriving
the corresponding upper bound on the DoFs, it is shown that the OIN scheme is
DoF optimal. Finally, numerical evaluation, a two-step scheduling method, and
the extension to multi-carrier scenarios are shown.Comment: 18 pages, 3 figures, Submitted to IEEE Transactions on Communication
Can One Achieve Multiuser Diversity in Uplink Multi-Cell Networks?
We introduce a distributed opportunistic scheduling (DOS) strategy, based on
two pre-determined thresholds, for uplink -cell networks with time-invariant
channel coefficients. Each base station (BS) opportunistically selects a mobile
station (MS) who has a large signal strength of the desired channel link among
a set of MSs generating a sufficiently small interference to other BSs. Then,
performance on the achievable throughput scaling law is analyzed. As our main
result, it is shown that the achievable sum-rate scales as
in a high signal-to-noise ratio (SNR) regime, if the
total number of users in a cell, , scales faster than
for a constant . This
result indicates that the proposed scheme achieves the multiuser diversity gain
as well as the degrees-of-freedom gain even under multi-cell environments.
Simulation results show that the DOS provides a better sum-rate throughput over
conventional schemes.Comment: 11 pages, 3 figures, 2 tables, to appear in IEEE Transactions on
Communication
Tsunami Flooding Probability determined by Probability Distribution Type
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
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