IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 6, JUNE 2009
2983
Increasing Downlink Cellular Throughput with
Limited Network MIMO Coordination
Howard Huang, Senior Member, IEEE, Matteo Trivellato, Student Member, IEEE,
Ari Hottinen, Senior Member, IEEE, Mansoor Shafi, Fellow, IEEE,
Peter J. Smith, Senior Member, IEEE, and Reinaldo Valenzuela, Fellow, IEEE
Abstract—Single-user, multiuser, and network MIMO performance is evaluated for downlink cellular networks with
12 antennas per site, sectorization, universal frequency reuse,
scheduled packet-data, and a dense population of stationary
users. Compared to a single-user MIMO baseline system with 3
sectors per site, network MIMO coordination is found to increase
throughput by a factor of 1.8 with intra-site coordination among
antennas belonging to the same cell site. Intra-site coordination
performs almost as well as a highly sectorized system with 12
sectors per site. Increasing the coordination cluster size from 1
to 7 sites increases the throughput gain factor to 2.5.
Index Terms—MIMO, capacity, broadcast channel, multiuser
systems, simulations, cellular networks.
MU, or network MIMO. We assume a scheduled packetdata operation used in next-generation cellular networks. First
we consider SU-MIMO, MU-MIMO and sectorization with
no coordination. Secondly, we evaluate the value of network
MIMO coordination within a site and across multiple sites.
Studies have addressed the performance of SU-MIMO in the
presence of colored interference [7], [8] and in cellular networks [9]–[11]. However they do not consider design tradeoffs
with sectorization and MU-MIMO. Performance evaluation of
network MIMO often employs an equal-rate (as opposed to
scheduled packet) criterion [4], [6] or use simplified cellular
models in order to obtain analytic results [5].
I. I NTRODUCTION
II. S YSTEM MODEL
ULTIPLE antenna techniques, also known as multipleinput multiple-output (MIMO) techniques, can provide significant performance gains over conventional singleantenna techniques [1]. While earlier MIMO research focused
on so-called single-user (SU) MIMO techniques, where spatially multiplexed channels are allocated to a single user, a
more recent topic is the study of multiuser (MU) MIMO
techniques [2], where a transceiver with multiple antennas
spatially multiplexes data among multiple users. An important
application of MIMO techniques is in cellular networks where
intercell interference is an impediment to system performance
[3]. By coherently coordinating the transmission and reception
among multiple bases, one can achieve improvements in
throughput for systems that would otherwise be interference
limited. This technique, sometimes known as network MIMO,
has been studied for both the downlink [4], [5] and uplink [6].
In this paper, we present a unified comparison of throughput
performance for downlink cellular networks employing SU,
We consider a downlink cellular network with B clusters
of M antennas each, serving K users with N antennas each.
The antennas belonging to a given cluster transmit in a
coordinated manner, and clusters operate independently. Under
sectorization, each cluster corresponds to the sector of a single
cell site. Under coordination, each cluster spans one or more
cell sites. Users are dropped uniformly in the network, and
each is assigned to the cluster with maximum average SNR
based on pathloss and shadowing as described in Section
IV. We let Sb denote the set of users assigned to cluster
b, with b = 0, . . . , B − 1. We are interested in determining
the throughput performance of cluster 0 in the presence of
interference from the other B − 1 clusters. For the kth user
assigned to cluster b = 0, the received signal is:
M
Manuscript received October 7, 2008; revised October 8, 2008; accepted
January 15, 2009. The associate editor coordinating the review of this paper
and approving it for publication was M. Win.
H. Huang and R. Valenzuela are with the Wireless Communications
Research Department, Bell Labs, Alcatel-Lucent, New Jersey, USA (e-mail:
{hchuang, rav}@alcatel-lucent.com).
M. Trivellato is with the Department of Information Engineering at the
University of Padova, Italy (e-mail: matteo.trivellato@dei.unipd.it).
A. Hottinen is with the Nokia Research Center, PO Box 407, 00045 Nokia
Group, Finland (e-mail: ari.hottinen@nokia.com).
M. Shafi is with the Telecom New Zealand, PO Box 293, Wellington, New
Zealand (e-mail: mansoor.shafi@telecom.co.nz).
P. J. Smith is with the Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand (e-mail:
p.smith@elec.canterbury.ac.nz).
Digital Object Identifier 10.1109/TWC.2009.080179
yk = Hk,0 x0 +
B−1
Hk,b xb + nk
(1)
b=1
where Hk,b is the N × M complex channel matrix between
cluster b and user k, xb is the M -dimensional transmitted
signal from cluster b, and nk ∼ CN (0, IN ) is an additive
complex white Gaussian noise vector with identity covariance
matrix. Clusters with indices 1, . . . , B − 1 correspond to the
other clusters in the network that cause interference to this
user. We assume a block fading model for the channel so that
it is static over one symbol interval and assume an average
sum power constraint (SPC) P for the M transmit antennas
in each cluster, i.e. trace(E[xb xH
b ]) ≤ P , where superscript H
denotes the Hermitian transpose.
The transmitted signal xb is a summation of the signals
for users in Sb , and in general these signals could be nonlinearly processed. Under linear precoding the signal trans-
c 2009 IEEE
1536-1276/09$25.00
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2984
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 6, JUNE 2009
mitted by cluster b is given by xb = j∈Sb Gj sj , where dj ,
Gj ∈ CM×dj and sj = [sj (1), . . . , sj (dj )]T are the number of
transmitted streams, the precoding matrix and the information
symbol vector for user j, respectively.
III. T RANSMISSION STRATEGIES
In order to reflect the operation of a next-generation packetbased cellular network, we assume that the average number
of users per sector is much larger than the number of transmit
antennas per sector. During the nth transmission interval,
a scheduler generates a quality of service (QoS) weight
qk (n) for each user k (k = 1, . . . , K). Using the multiuser
proportional fair scheduling (MPFS) algorithm [12], each
user’s QoS weight is the reciprocal of its windowed average
rate. A resource allocation algorithm, described below, then
determines the set of active users S(n) and user rates to
maximize the QoS-weighted sum rate. The MPFS algorithm
allows us to maximize the sum rate while maintaining fairness
for cell-edge users. In the following, for ease of notation, we
drop the cluster index b.
For SU-MIMO, we use the capacity-achieving closedloop BLAST technique that performs waterfilling over the
eigenmodes of a given user’s MIMO channel [1]. Since
each cluster transmits to only a single user during a given
interval, the set S(n) is simply the index of the single user with the largest weighted rate: S(n) = {k̃} =
arg maxk qk (n)rSU,k (Hk (n), P ), where rSU,k (Hk (n), P ) is
the SU MIMO capacity for user k. The actual transmitted rate
during interval n is:
RSU (n) = rSU,k̃ (Hk̃ (n), P ).
(2)
In case of MU MIMO we consider three different transmission techniques: 1) a scheme based on ZF beamforming
that selects the active users and possible multiple streams per
user in order to maximize the weighted sum rate (denoted
as ZF-m) [13], 2) ZF beamforming where only the dominant
eigenmode of each user can be selected for transmission (ZF1) [13] and 3) the capacity achieving dirty paper coding
(DPC) [14]. Both in ZF-m and ZF-1 the streams transmitted
by a cluster are non-interfering as a consequence of the ZF
constraint. Let us denote the collective set of user MIMO
channels in time interval n as H̄(n) = {H1 (n), . . . , HK (n)}.
For ZF-1 the rate achievable by user k ∈ S(n) as a function
of the power wk assigned to this user is rk (wk , S(n)) =
log2 (1 + wk vk2 (H̄(n), S(n))) where 1/vk2 (H̄(n), S(n)) is the
effective noise power as a result of the ZF beamforming. This
power is a function of the users’ MIMO channels in the set
S(n) and its derivation is given in [13]. The optimal achievable
rate vector is determined by first finding the optimum power
vector w for a given set S and then maximizing over all
possible sets S, subject to constraints on the power:
rZF −1 (q(n), H̄(n), P ), S(n) =
arg max max
qk (n)rk (wk , S) (3)
r,S
S
w
k∈S
subject to wk ≥ 0 (k = 1, . . . , K) and F (w) ≤ P,
where F (w) is the total transmit power as a function of
the individual transmit powers for the users in set S. The
optimization with respect to w is calculated using waterfilling.
The outer optimization with respect to S requires a brute
force search over all possible sets. However, we use a simple
greedy allocation algorithm based on [15] where users are
added successively one at a time up to a maximum of M
only if the weighted throughput is increased. This greedy user
selection algorithm has been shown to provide near-optimum
performance when the number of users K is large. The sum
rate throughput is simply the component-wise sum of the rate
vector:
rZF −1,k (q(n), H̄(n), P ).
RZF −1 (q(n), H̄(n), P ) =
k∈S(n)
(4)
The generalization of this technique for ZF-m is given in [13].
For DPC the resource allocator determines the point on
the boundary of the capacity region which maximizes the
weighted sum rate:
rDP C (q(n), H̄(n), P ) =
arg max
K
qk (n)rk (n),
r(n)∈C(H̄(n),P ) k=1
(5)
where rk (n) is the kth element of vector r(n), the capacity region C is defined in [14], and the rate vector
rDP C (q(n), H̄(n), P ) that maximizes the metric can be
computed numerically [16]. The sum rate during this interval is given by the element sum of the rate vector
rDP C (q(n), H̄(n), P ):
RDP C (n) =
K
rDP C,k (q(n), H̄(n), P ).
(6)
k=1
IV. C ELLULAR SYSTEM SIMULATION METHODOLOGY
The channel coefficient between each transmit and receive
antenna pair is a function of distance-based pathloss, shadow
fading, and Rayleigh fading. We let the (n, m)th element (n =
1, . . . , N, m = 1, . . . , M ) of the kth user’s MIMO channel
matrix Hk,b from cluster b be given by:
(n,m)
γ
n,m
A(θk,b(m) ) [µk,b /µ0 ] ρk,b Γ
(7)
Hk,b = βk,b
n,m
n,m
is independent Rayleigh fading, βk,b
∼
where βk,b
CN (0, 1), A(θk,b(m) ) is the antenna element response as a
function of the direction from the mth antenna of the bth
cluster to the kth user, µk,b is the distance between the bth
cluster and the kth user, µ0 is a fixed reference distance,
γ = 3.5 is the pathloss coefficient, and ρk,b is the lognormal
shadowing between the bth cluster and kth user with standard
deviation σρ = 8 dB. Since shadowing is caused by large
scatterers we assume that antennas of the same cell are close
enough to be characterized by the the same shadowing effect.
We assume universal frequency reuse, so that all clusters
transmit on the same frequency. The variable Γ is the reference
SNR defined as the SNR measured at the reference distance
µ0 , assuming a single antenna at the cell center transmits at
full power and accounting only for the distance-based pathloss.
If we let µ0 be the distance from the cell center to the cell
boundary, a reference SNR Γ = 20dB captures the various
power and noise parameters associated with a typical outdoor
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HUANG et al.: INCREASING DOWNLINK CELLULAR THROUGHPUT WITH LIMITED NETWORK MIMO COORDINATION
cellular network operating in the interference-limited regime
[6].
A. No coordination and
(C = 1)-cell coordination
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B. (C = 3)-cell coordination
For all simulations, there are 12 antennas per cell site. The
antennas are grouped and oriented so there are S = 3, 6
or 12 sectors per cell, with the orientations shown in Fig.
2. The antennas are spaced sufficiently far apart so they are
spatially uncorrelated. We model the antenna element response
as an inverted parabola that is parameterized by the 3 dB
beamwidth
θ3dB and the sidelobe power As measured in
dB: A(θk,b(m) ) dB = − min{12(θk,b(m) /Θ3dB )2 , As } where
θ ∈ [−π, π] is the direction of user k with respect to the
broadside direction of the mth antenna of cluster b. For
the case of coordination, the broadside direction could be
different for the M antennas as we discuss later. As the
sectorization order increases, the beamwidth decreases, and
the physical width of each sector’s antenna changes inversely
proportionally to the beamwidth [17]. For S = 3, 6, 12, the
corresponding parameters are Θ3dB = (70/180)π, (35/180)π,
(17.5/180)π and As = 20, 23, 26 dB, respectively.
A total of 60 users are uniformly dropped in each cell
site, and users are assigned to the cluster with the highest
average SNR accounting for distance-based pathloss and shadowing. For each drop of users, the channel is modelled as
Hk,b ∼ CN (0, I) and we assume a time-division duplexed
(TDD) system with stationary users so that channel state
information (CSI) at the transmitter is ideal. Perfect CSI is
also assumed at the receiver. Each simulation is run over
thousands of transmission intervals and to provide fairness
in the network, after each interval, the user QoS weights are
updated according to the MPFS algorithm with fairness factor
τ = 10 time slots.
We model the link performance using the Shannon limit
with a 3dB (factor of 1/2) power penalty per stream for all
techniques except for DPC so it provides a true upper bound.
With this approach we are implicitly assuming that there is a
rich set of modulation and coding rates but at the same time
we provide a practical way to account for link inefficiency. The
3dB offset provides a good approximation for the performance
of an AWGN link using typical 3G coding, modulation and
block sizes at 1% packet error rate [18].
The cell layout and the number of cells in the network
depends on the type of simulation. First we consider S =
3, 6, 12 sectors per cell site without coordination (no-C) in a
B = 19-cell network, as in Fig. 1A.
For the second set of numerical results, we study the impact
of coordination. We let C denote the number of cell sites in
the coordination cluster and consider no-C, C = 1, 3, and 7.
We assume that the antenna elements are sectorized according
to the parameters for S = 3 and the corresponding sector
orientation in Fig. 2. For C = 1, the 12 co-located antennas
for each cell site form a coordination cluster. The number of
independent clusters is B = 19 as shown in Fig. 1A. For
C = 3 and 7, each cluster uses M = 36 and 84 antennas,
respectively, and the layouts are given by Fig. 1B and C,
respectively. The number of clusters in the network is B = 7
C. (C = 7)-cell coordination
Fig. 1. Cell layout showing clusters of coordinated cell site antennas. Under
sectorization with no coordination, S = 3, 6, 12 independent sectors per cell
are used. Under coordination, antenna elements are sectorized according to
parameters and orientation for S = 3.
S=3
S=6
S = 12
Fig. 2. Sectorization with S = 3, 6, 12 sectors per cell (M = 4, 2, 1
antennas per sector, respectively) where the arrow indicates the boresight
direction of a representative sector’s antennas. If a user lies in the direction
of the arrow, then (A(θk,b ))dB = 0.
for both C = 3 and 7. 1
Colored inter-cluster interference is accounted for using
a two-phase methodology. In the first phase, the resource
allocation and transmit covariance calculations are performed
assuming the inter-cluster interference is spatially white and
estimating the achievable SINR assuming all clusters transmit
at full power and accounting for path loss and shadowing. In
the second phase, the actual achievable rates are computed
assuming that the transmit covariances are colored according
to sample covariances generated from the first phase. The
assumption of spatially white noise in the first phase is
the worst-case noise and results in a somewhat pessimistic
rate. This methodology circumvents the problem of resource
1 We note that in case of coordination between spatially separated antennas
(C = 3, 7) it would be necessary to consider an average per-site power
constraint instead of the SPC introduced in Section II. Off-line analysis of
the power allocation per site indicates that under SPC, the distribution of
power is nearly the same for all sites. This observation indicates the marginal
performance difference under a per-site constraint would be minimal.
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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 6, JUNE 2009
allocation when the statistics of the colored spatial noise are
not known. In order to achieve the rates predicted in the
presence of colored noise, we assume that fast incremental
redundancy or some other higher level medium access protocol
is employed to progressively adapt the rates.
Cell-site wraparound is used to prevent network edge effects
by ensuring each cell is surrounded by a sufficient number
of interfering cells. For the case of no-C and C = 1-cell
coordination, wraparound is used so each cell is surrounded
by two rings of cells. Each cell is at the center of its own
network, as shown in Fig. 1A. Similarly, for the case of C =
3 and C = 7-cell coordination, cluster wraparound is used
so that each cluster is surrounded by one ring of clustered
cells. Even though the network topology changes with C, the
comparisons are valid because at least two rings of interfering
cells are always considered; considering more cells as source
of interference would have a negligible effect on the user SINR
statistics.
1
0.9
CLB, S=6
ZF−1, S=3
0.8
ZF−1, S=6
DPC, S=12
CLB, S=3
0.7
0.6
DPC, S=3
cdf
2986
S=12
0.5
0.4
DPC, S=6
0.3
w/ 3dB
0.2
w/o 3dB
0.1
0
0
10
20
30
cell throughput [bit/s/Hz]
40
50
Fig. 3. CDF of spectral efficiency per cell (bps/Hz) for fixed number of
antennas per cell. S = 3, 6, 12 sectors per cell, 12 antennas per cell, N = 1
antenna per user, no coordination. The CLB and ZF performance includes a
3dB power penalty per stream.
V. N UMERICAL RESULTS
We present two sets of simulation results showing the
cumulative distribution function (CDF) of spectral efficiency
per cell calculated according to the sum rate expressions given
in Section III. Performance is measured per cell to facilitate
comparison across all results.
A. Impact of Sectorization
In the first set of results, we compare the per cell throughput
with 12 antennas per site, arranged in S = 3, 6, 12 sectors with
M = 4, 2, 1 antennas per sector, respectively. We first consider
the SU-MIMO performance using CLB for N = 1 in Fig. 3.
With only a single antenna, no spatial multiplexing is possible.
In going from S = 3 to 6, the diversity and combining order
drops from M = 4 to 2. However, this drop which occurs per
sector is offset by the doubling in the number of sectors per
cell. Overall, the median cell spectral efficiency increases by
about 35%. A similar gain is observed for N = 2 in Fig. 4
where multiple receive antennas allow for spatial multiplexing.
Comparing CLB and ZF-1, CLB transmits to a single user
using N streams whereas ZF-1 transmits a single stream to
as many as M users. For the case of S = 6, M = 2, N = 2,
even though CLB and ZF-1 have the same multiplexing order,
the ZF-1 performance is superior because of the multiuser
diversity advantage. For the other cases with S = 3 or 6, ZF-1
has a clear multiplexing advantage. For MU MIMO when N =
2 (see Fig. 4) we have the option of allocating multiple streams
to a single user using ZF-m. We observe that the performance
gain over the more restrictive ZF-1 is minimal, meaning that
multiuser diversity can compensate for the reduced potential
multiplexing gain per user. Moreover, ZF-1 is more robust in
the presence of colored intercell interference and less complex
to implement, requiring less control signalling and feedback
overhead.
For both CLB and ZF, performance improves in going from
three to six sectors. For CLB, the improvement is the result
of higher order multiplexing. However for ZF, the maximum
number of spatial channels per cell is fixed to 12, indicating
that the spatial channels formed by sectorization are more
effective than those formed by ZF beamforming. For both
CLB and ZF, the performance is further improved in going
from S = 6 to 12 sectors. In this case, since there is only
M = 1 antenna per sector, no spatial multiplexing can be
achieved, and the CLB and ZF techniques are equivalent. The
superior performance of S = 12 comes at the expense of larger
antenna elements, as mentioned in Section IV. In general, we
observe that without coordination, higher-order sectorization
improves throughput for a fixed number of antennas per cell
site.
Regarding DPC, in the case of single antenna users, the
opposite trend regarding sectorization is observed. In other
words, the CDF slightly shifts to the left as the number of
sectors goes from S = 3 to 6. The reason is that the spatial
channels formed with DPC are more effective than those
formed by sectorization. On the other hand, for N = 2 under
DPC, the performance improves as S increases. The reason
is that the transmit covariances during the first phase of the
simulation methodology are created assuming spatially white
interference while performance is measured in the presence
of colored interference. Therefore with higher order sectorization, inter-cell interference appears more spatially white and
there is less performance loss when the spectral efficiency is
actually computed.
B. Impact of network coordination
We compare the per-cell throughput when coordinating antennas among C = 1, 3, 7 sites with M = 12, 36, 84 antennas,
respectively. In going from no coordination up to C = 7cell coordination for ZF-1, the median spectral efficiency
increases by about 70% for single antenna users (see Fig. 5)
and 60% for multiple antenna users (see Fig. 6). Coordinating
antennas within the same site provides the largest gains by
eliminating intra-site interference. Diminishing returns occur
as the coordination cluster size increases, indicating that
interference mitigation is not effective once the interference
power is equal or below that of the background additive noise.
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HUANG et al.: INCREASING DOWNLINK CELLULAR THROUGHPUT WITH LIMITED NETWORK MIMO COORDINATION
1
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1
0.9
CLB, no−C
0.9
ZF−1, no−C
ZF−1, S=3
0.8
ZF−1, C=1
0.8
ZF−1, S=6
0.7
0.6
0.5
ZF−m, S=6
0.4 CLB, S=3
ZF−1, C=7
0.6
DPC, S=6
CLB, S=6
cdf
cdf
ZF−1, C=3
0.7
DPC, S=3
S=12
0.5
DPC, C=1
DPC, no−C
0.4
DPC, S=12
ZF−m, S=3
DPC, C=3
0.3
0.3
0.2
0.1
0
0
w/ 3dB
0.2
w/o 3dB
w/o 3dB
w/ 3dB
0.1
10
20
30
cell throughput [bit/s/Hz]
40
50
Fig. 4. CDF of spectral efficiency per cell (bps/Hz) for fixed number of
antennas per cell. S = 3, 6, 12 sectors per cell, 12 antennas per cell, N = 2
antennas per user, no coordination. The CLB and ZF performance includes a
3dB power penalty per stream.
0
0
10
20
30
40
cell throughput [bit/s/Hz]
50
60
70
Fig. 6. CDF of spectral efficiency per cell (bps/Hz), 12 antennas per cell,
S = 3 antenna configuration, no-C, C = 1, 3, 7-cell coordination, N = 2
antennas per user. The CLB and ZF performance includes a 3dB power penalty
per stream.
VI. C ONCLUSIONS
1
CLB, no−C
0.9
DPC, no−C
0.8
ZF−1, no−C
0.7
ZF−1, C=1
cdf
0.6
DPC, C=1
ZF−1, C=3
0.5
ZF−1, C=7
DPC, C=3
0.4
0.3
w/ 3dB
0.2
w/o 3dB
0.1
0
0
10
20
30
40
cell throughput [bit/s/Hz]
50
60
70
Fig. 5. CDF of spectral efficiency per cell (bps/Hz), 12 antennas per cell,
S = 3 antenna configuration, no-C, C = 1, 3, 7-cell coordination, N = 1
antenna per user. The CLB and ZF performance includes a 3dB power penalty
per stream.
Therefore network coordination gains are higher for higher
transmit powers (in other words, higher cell edge SNR). A
similar observation was made for uplink network coordination
in [6]. Note that the ZF-1 performance with C = 1-cell
coordination is comparable to the S = 12-sector case. ZF1 with C = 1 presents a favorable performance-complexity
tradeoff since it can be implemented with a much smaller
antenna array and minimally complex coordination among
co-located antennas. The gains of coordination for DPC are
much higher where, with C = 3-cell coordination, the CDF
median is almost double the case of no coordination. If we
consider CLB with S = 3 sectors and M = 4 antennas per
sector as a baseline, then ZF-1 with C = 7-cell coordination
gives an approximate 2.5-fold improvement in median spectral
efficiency for both N = 1 and 2.
We evaluated the throughput performance of MIMO techniques under a unified simulation environment that models a
multicell system with 12 antennas per cell site, serving a dense
population of stationary users with scheduled packet data.
For a given sectorization order, MU-MIMO outperforms
SU-MIMO because of more efficient spatial multiplexing. For
a fixed number of antennas per cell, throughput increases
as the number of sectors per cells increases, at the cost
of larger antennas. Coordinating transmissions via network
MIMO across one or more cells improves throughput by mitigating interference but requires additional backhaul resources
and higher computational complexity.
Compared to a SU-MIMO baseline with S = 3 sectors
per cell, network MIMO, using the same antenna architecture
but with only modest coordination among co-located antennas,
effectively eliminates the notion of sectors and increases the
median throughput by a factor of 1.8. Its performance nearly
matches the case of maximum sectorization order but requires
a much smaller antenna array. By coordinating a cluster of
seven cells, the throughput gain increases to 2.5.
These results assume a narrowband model and ideal channel
state information at both the transmitter and receivers. Future studies should consider wideband channels with timefrequency scheduling and the impact of imperfect channel
state information.
VII. ACKNOWLEDGEMENTS
The authors gratefully acknowledge their employing organisations who provided the facilities and time to do this work.
Ari Hottinen was supported during this work by the EU FP6
STREP project (project No. IST-026905(MASCOT).)
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Howard Huang received a BS in electrical engineering from Rice University in 1991 and a Ph.D.
in electrical engineering from Princeton University
in 1995. Since then, he has been a researcher at
Bell Labs (Alcatel-Lucent) in Holmdel, New Jersey,
currently as a Distinguished Member of Technical
Staff in the Wireless Access Domain. On behalf
of Bell Labs, he has proposed MIMO technologies in 3GPP standards for UMTS, LTE, and LTE
Advanced standards. Dr. Huang’s research interests
are in MIMO system design for cellular networks,
multiuser detection, and antenna array design. He holds over a dozen patents
and is a Senior Member of the IEEE.
Matteo Trivellato was born in Padova, Italy on
March 13th, 1981. He received the Laurea degree,
summa cum laude, in Telecommunication Engineering from the University of Padova, Italy in
2005. Since 2006 he has been a Ph.D. student in
Information Engineering at University of Padova,
Italy. In 2007 he was an intern at Alcatel-Lucent,
Bell Labs, Holmdel, NJ, in the Wireless Research
Group, working on multiuser MIMO transmission
techniques for downlink and uplink communications. His main research interests include MIMO
multiuser communications, networked control systems, channel estimation and
synchronization in multicarrier systems.
Ari Hottinen graduated with an MSc in Applied
Mathematics from the University of Helsinki in
1992, and obtained a DSc degree (with distinction)
in Computer Science and Engineering in 2004 from
Helsinki University of Technology. He joined Nokia
Cellular Systems in 1992 and Nokia Research Center in 1994. Currently, he is a Principal Member of
Research Staff at Nokia Research Center in Helsinki,
Finland working on wireless system design, cognitive radio, relay networks and MIMO systems.
He was the Nokia representative in an EU STREP
project MASCOT related to multiuser MIMO and relay network research. Dr.
Hottinen is an inventor or co-inventor in approximately 60 granted patents in
the area of wireless communications, and he has published over 80 conference
and journal papers in wireless communications. He has co-authored the book
Multi-Antenna Transceiver Techniques for 3G and Beyond (Wiley 2003).
Mansoor Shafi received his B.Sc (Engineering) in
Electrical Engineering from Engineering University,
Lahore, Pakistan and PhD degrees from the University of Auckland, Auckland New Zealand in 1970
and 1979 respectively. From 1975 to 1979 he was a
Junior Lecturer at the University of Auckland. Since
1979 he has been with Telecom New Zealand, where
he now holds the position of Principal Advisor Wireless Systems. His research interests are in Wireless
Communications. He has published widely in IEEE
Journals and IEEE Conferences in the areas of Radio
Propagation, Signal processing, MIMO Systems, and Adaptive Equalization.
He was a guest editor of a two JSAC special issue of MIMO systems published
in April and June 2003. He also co edited a JSAC special issue on MIMO
in Aug 2008 and an IEEE proceedings special issue on Cognitive radio. This
special issue will appear in early 2009.
His, co-authored, paper, “From Theory to Practice: An Overview of MIMO
Space-Time Coded Wireless Systems," published in JSAC April 2003 won the
IEEE Communications Society best tutorial paper award in 2004. Mansoor is
a Fellow of the IEEE and an Adjunct Professor at Canterbury and Victoria
Universities. He was a Cochair of the ICC 2005 Wireless Communications
Symposium, held in Seoul. In Telecom New Zealand his role is to advise
Telecom management on the future directions of Wireless Technologies and
standards. Dr Shafi is also an editor of the IEEE T RANSACTIONS W IRELESS
C OMMUNICATIONS.
Peter J. Smith (M’93) received the B.Sc degree in
Mathematics and the Ph.D degree in Statistics from
the University of London, London, U.K., in 1983
and 1988, respectively. From 1983 to 1986 he was
with the Telecommunications Laboratories at GEC
Hirst Research Centre. From 1988 to 2001 he was a
lecturer in statistics at Victoria University, Wellington, New Zealand. Since 2001 he has been a Senior
Lecturer and Associate Professor in Electrical and
Computer Engineering at the University of Canterbury in New Zealand. His research interests include
the statistical aspects of design, modelling and analysis for communication
systems, especially antenna arrays, MIMO, cognitive radio and relays.
Authorized licensed use limited to: University of Canterbury. Downloaded on November 19, 2009 at 21:35 from IEEE Xplore. Restrictions apply.
HUANG et al.: INCREASING DOWNLINK CELLULAR THROUGHPUT WITH LIMITED NETWORK MIMO COORDINATION
Reinaldo A. Valenzuela obtained his B.Sc. at the
University of Chile, and his Ph.D. from Imperial
College of Sc. and Tech., U. of London, England. At
Bell Laboratories, he carried out indoor microwave
propagation measurements and developed statistical models. He also worked on packet reservation
multiple access for wireless systems and optical
WDM networks. He became Manager, Voice Research Dept., at Motorola Codex, involved in the
implementation of integrated voice and data packet
systems. On returning to Bell Laboratories he was
involved in propagation measurements and ray tracing propagation prediction. He received the Distinguished Member of Technical Staff award and
is Director of the Wireless Communications Research Department. He is
currently engaged in MIMO / space time systems achieving high capacities
using transmit and receive antenna arrays. He has published over one hundred
papers and has twelve patents. He is a Fellow of the IEEE. He has been
editor of the IEEE T RANSACTIONS ON C OMMUNICATIONS and the IEEE
T RANSACTIONS ON W IRELESS C OMMUNICATIONS.
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