5G Millimeter-Wave and Device-to-Device Integration

By: Niloofar BahadoriAdvisors: Dr. B Kelley,

Dr. J.C. Kelly

Spring 2017

Outline

• 5G communication Networks• Why we need to move to higher frequencies?• What are the characteristics of mmWave band communications?• What are the challenges in using mmWave?• How mmWave challenges can improve D2D communication performance?• Challenges of D2D mmWave • Hybrid D2D network• Simulation Result

Network Specification 5G 4G

Peak Data Rate 10 Gb/s 100 Mb/s

Mobile Data Volume 10 Tb/s/k𝑚2 10 Gb/s/k𝑚2

E2E Latency 5 ms 25 ms

Energy Efficiency 10% current consumption

Number of Devices 1 M/k𝑚2 1 k/k𝑚2

Mobility 500 km/h -

Reliability 99.999% 99.99%

5G networks

Existing solutions to improve network capacity:• Increase Available BW

• Carrier Aggregation• Cognitive Radio

• Spectrum Reuse• D2D Communication • Small Cell network

• Increase Spectral Efficiency • Massive MIMO• Spectrum Sharing

Even though some of these techniques can boost performance significantly, there is no clear

roadmap on how to achieve the so far defined 5G performance targets.

Carrie #1: 20 MHz

Carrie #2: 20 MHz

Carrie #3: 20 MHz

Carrie #4: 20 MHz

Carrie #5: 20 MHz

100 MHz

5G networks

AM Broadcast

TV Broadcast

Cellular Communication

Wi-Fi

Equivalent Spectrum

U.S. Frequency AllocationThe Radio Spectrum

Source: U.S. Dept. of Commerce, NTIA Office of Spectrum Management

• Microwave band is referred to as Sweet spot due to its favorable propagation characteristics• Low frequency bands have been almost used up• It is difficult to find sufficient frequency bands in the microwave range for 5G improvements• mmWave with high bandwidth can be a potential solution for 5G communication• However, wave propagation in mmWave band has specific characteristics that should be considered

in design of network architecture

3 GHz 57-64 164-200 300 GHz

Cellular communication

54 GHz 99 GHz 99 GHz

Oxygen molecule Absorption Water Absorption

Potential available bandwidth

mmWave Communication

Candidate Bands

27.5–28.35 31.225–31.3

29.1–29.25 71-76

31.075–31.225 81-86

31.0–31.075 92-95

Atmospheric Absorption• Raindrops are roughly the same size as the radio wavelengths (millimeters) and therefore cause scattering

of the radio signal • The rain attenuation and molecular absorption characteristics of mmWave propagation limit the range of

mmWave communications

mmWave Characteristics

Source: E-band technology. E-band Communications. [Online]. Available: http://www.e-band.com/index.php?id=86.

The rain attenuation and atmospheric

absorption do not create significant

additional path loss for cell sizes on the order

of 200 m.

mmWave CharacteristicsHigh Propagation Loss and Sensitivity to Blockage• mmWave communication suffers from high propagation loss 𝑃𝐿 ∝ 𝑓2

• Electromagnetic waves have weak ability to diffract around obstacles with a size significantly larger than the wavelength

• For example, blockage by a human attenuate the link budget by 20-30 dB• Only LOS communication is efficient.

Frequency Band (GHz)

PLE- LOS PLE- NLOS Rain Attenuation @200 m (dB)

Oxygen Absorption

@200 m (dB)

28 1.8~1.9 4.5~4.6 0.9 0.04

38 1.2~2 2.7~3.8 1.4 0.03

60 2.23 4.19 2 3.2

73 2 2.45~2.69 2.4 0.09

𝐹 𝑑 = 𝑃𝐿(𝑑0) + 10𝑛𝑙𝑜𝑔10𝑑

𝑑0

Path-loss Exponent (PLE)

LOS path

NLOS path

NLOS suffer from high attenuation

mmWave CharacteristicsDirectivity• To combat severe propagation loss, high gain, directional

antennas are employed at both transmitter and receiver• Beamforming is a key enabling technology of mmWave

communication• With a small wavelength, electronically steerable antenna

arrays can be realized as patterns of metal on circuit board

Directional antenna High gain at one

directionvery low gain in all

other directions

IBM: The packaged transceiver operates at frequencies in the

range of 90-94 GHz. It is deployed as a unit tile,

combining 4 phased array ICs and 64 dual-polarized

antennas.

IBM Breakthrough Could Alleviate Mobile Data Bottleneck

IEEE RFIC 2014 Seattle, WA

D2D Communication

D2D communication allows mobiles to establish a direct connection without traversing the eNodeB (or BS).D2D is a key component in the context of IoT, since a substantial fraction of the traffic is generated and consumed locally.Eliminating the eNodeB from the transmission path leads to:• Higher spectral efficiency• Lower signaling overhead• Higher energy efficiency• Increase the coverage of cell edge UEs• Reduce the traffic load of BS

However, these gains can only be achieved if we can overcome several challenges faced by D2D communication.

D2D Communication

Main problem in D2D: Interference Management

D2D over ISM band (using WiFi)• Devices compete to achieve channel

access• Little interference control• Quality of communication is not

guaranteed.

D2D over licensed band• Guaranteed communication quality• Require accurate interference management

between cellular and D2D users

Several techniques are proposed to solve these challenges. Still D2D link capacity is significantly affected by the network density:• Insufficient communication bandwidth• Significant interference caused due to the omni-directional nature of communication

mmWave Shortcomings Advantage for D2DSome of the mmWave communication challenges are desirable features for D2D communication: • High path loss• Directional beam forming

• Less interference • Improve spatial reuse

• High bandwidth• Supports high throughput D2D applications

Challenges• Narrow beam width• Low antenna height in D2D communication comparing to BS heightMakes devices more vulnerable to blockage which may cause difficulty to fulfill D2D device discovery and beam alignment.

Hybrid communication: works on mmWave in Line-of-Sight (LoS) case and switch back to microwave in case of blockage, and exchange control signaling in microwave to aid the alignment for mmWave.

mmWave D2D integration

Beam alignment protocol1. BS finds that there is a UE who wants to communicate directly with another UE in its cell 2. BS broadcasts this information as a D2D-link-set-up-request to both UEs. 3. DUE pair receive the request and prepare for the beam alignment process (micro wave

band)4. DUE A will send channel probing signals from each of its sectors in a cycle, and B will

receive at each of its sectors and keep recording the signal strength (𝐴𝑘 × 𝐵𝑛)5. BS gets the feedback of the power strength from B and convey information to A.

LoS Link: If the mmWave power received by B in some sector is greater than a minimum power threshold (T), BS will send A the information: mmWave communication.Blockage: If none of B’s sectors received enough power higher than the threshold, which shows there are blockages in the link, BS will inform A to communicate with B on micro wave band

6. A begins to communicate with B in micro wave or mmWave. 𝑃11 ⋯ 𝑃1𝑛⋮ ⋱ ⋮𝑃𝑘1 ⋯ 𝑃𝑘𝑛

Ak…A1 Bn…B1

mmWave D2D integration

AssumptionsLocation of BSs: The locations of the BSs form a homogeneous Poisson Point Process (PPP) 𝜙 on the plane with density 𝜆𝐵 and all BSs employ constant downlink transmission power 𝑃𝐵.Location of DUEs: The D2D users form another homogeneous PPP 𝜙 on the plane with density 𝜆𝐷 . The DUE reuse the downlink resource of the cellular links. Blockage model: The blockages are modeled as another PPP of buildings independent of the communication network. Each point of the building PPP is independently marked with a random width, length, and orientationBeam-Forming : In millimeter wave band, antenna arrays at the base stations and DUEs are all adopted for directional communication. Angle gain between the transmitter beam and the receiver beam is denoted as 𝐺(𝜃𝑡, 𝜃𝑟), and the maximum achievable array gain is 𝐺(0, 0). In microwave band they use omni-directional antenna.Beam Alignment: Due to small size of antenna, they can be used in large scale at equipment to obtain high gain communication. The main beams of the transceiver antennas are perfectly aligned with each other when transmission is being carried on.

mmWave D2D integration

Converge probability:𝑃 = 𝑃 𝑆𝐼𝑁𝑅 > 𝑇

Microwave Mode:

𝛾𝑚𝑖𝑐𝑟𝑜 =𝜇𝑚𝑖𝑐𝑟𝑜𝑟

−𝛼ℎ𝐷𝐷𝐼𝐵𝐷 +𝐼𝐷𝐷 +𝜎

2

mmWave Mode:

Probability of blockage : 𝑎 = 1 − 𝑒−𝛽𝑑 , 𝛽 =2𝜆 𝑏𝑙𝑜𝑐𝑘𝑎𝑔𝑒𝐸 𝑤 𝐸[𝐿]

𝜋

𝛾𝑚𝑚 =𝜇𝑚𝑚α 0 𝑔(𝑟0)

𝜎2 + σ𝑘=0𝐾−1𝜇𝑚𝑚α[𝜃𝑘]𝑔(𝑟𝑘)

Hybrid Mode: 𝑃 𝑆𝐼𝑁𝑅 > 𝑇 = 𝑎 𝑃 𝑆𝐼𝑁𝑅𝑚𝑚 > 𝑇 + 1 − 𝑎 𝑃(𝑆𝐼𝑁𝑅𝑚𝑖𝑐𝑟𝑜 > 𝑇)

Parameter Value

Density of BSs 𝜆𝐵 1 × 10−6𝑚2

Density of DUEs 𝜆𝐷 1 × 10−5𝑚2

Density of Blockages 1 × 10−5𝑚2

Transmitting power of BS 𝜇 𝐵 30dBm

Transmitting power of DUE in micro wave 𝜇𝑚𝑖𝑐𝑟𝑜 23dBm

Transmitting power of DUE in mmWave 𝜇𝑚𝑚 23dBm

SINR threshold T -10dB

Microwave Path loss exponent 3

mmWave path loss 4

Noise Power -87dBm

Average blockage width 50m

Average blockage length 50m

Carrier frequency in mmWave 28 GHz

Simulation result

Simulation Result

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