Aliye Özge Kaya Wade Trappe Larry J. GreensteinWireless Information Network Laboratory (WINLAB)

{ozgekaya, trappe, ljg} @winlab.rutgers.edu

Stochastic channel models ignore variations along a trajectoryWe develop a location-specific and time–varying MIMO channel model using an environment simulator: Simulated MIMO channels in Manhattan and Boston Compared location-specific performance for varying sizes, orientations, polarizations of the antenna arrays different MIMO transmission modes

Overview

Number of Antennas

Simulation Setup

Results Simulated the channel gain matrix to compute capacity and throughput versus distance Obtained CDFs of these metrics over the paths traversed for many cases. Similar results were obtained for other paths in both cities

Simulated for a fixed transmitter and varying receiver locations along a path 4x4 and 2x2 MIMO channel gain matrices Single antenna channel gain (SISO) Predicted the channel gain matrices in 5-cm steps on every path Environment simulator is WiSE (Wireless System Engineering), a ray-tracing tool developed by Alcatel-Lucent Total transmit power is 10 dBm, Center frequency is 2.4 GHz Transmitter and receiver are 2m high

TX P1 P2Lexington Ave

E 1

05th

St E 1

04th

St

E 1

03th

St

E 1

01th

St

E 1

02th

St

Fig. 1 A partial street plan in Manhattan. The transmitter is fixed at Tx and the receiver moves from P1 to P2, a 323-m path in 5-cm steps.

Polarization and Diffraction Array Orientation

MIMO Transmission Mode

0 10 20 30 40 50 600

0.2

0.4

0.6

0.8

1

Capacity [bps/Hz]

CD

F o

f Ca

pa

city

Single Antenna2x2 MIMO4x4 MIMO

Fig. 2 CDFs of capacity for single antenna, 2x2 MIMO and 4x4 MIMO along the path in Fig.1

The average capacity for 4x4 MIMO is 90% more than the average capacity for 2x2 MIMO 2x2 gains 78% more capacity than SISO

10 15 20 25 30 35 40 45 50 55 600

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Capacity [bps/Hz]

CD

F of

Cap

acity

Isotropic antennnaHorizontal PolarizationVertical Polarization Vertical Polarization and Diffraction

Fig. 3 CDFs of capacity for isotropic antenna; horizontally and vertically polarized dipole antennas, both with and without diffraction effects considered , along the path in Fig.1 (4x4 MIMO)

Vertical polarization increases the capacity by 4.4 bps/Hz in compare to horizontal polarization Including diffraction in the simulations increases the predicted capacity by an average of 2bps/Hz

Spatial multiplexing is the best transmission mode to use at most locations on this path

0 50 100 150 200 250 3000

5

10

15

20

25

30

35

40

45

Distance [m]

Ave

rage

Cap

acity

[bps

/Hz]

WaterfillingBeamformingSpatial MultiplexingD-STTDSingle Antenna

Fig. 4 Variations of the maximum attainable throughput on the path in Fig.1. Each rate is averaged over a 1-m window (4x4 MIMO)

10 15 20 25 30 35 40 45 50 55 600

0.2

0.4

0.6

0.8

1

Capacity [bps/Hz]

CD

F of

Cap

acity

HorizontalVertical

Fig. 5 CDFs of capacity for horizontally and vertically oriented arrays on a 214-m path in Boston

Horizontally-oriented arrays yields an average capacity increase of 17 bps/Hz 68% rate improvement in compare to using vertical arrays

Publication:Aliye Özge Kaya, Wade Trappe , Larry Greenstein, "Adapting MIMO transmission mode along paths in urban environments”, submitted to ICASSP’10

Location-Specific MIMO Performance in Urban Wireless Channels

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