5G Enabled Vehicular Networks

1. 5G ENABLEDVEHICULAR
NETWORKS
School of Electronics and Communication Engineering
South China University ofTechnology

2. overview
■ Introduction
■ Purpose of vehicular communication
■ CommunicationTechnology
■ Calculation
■ Simulations results
■ Future work

3. Introduction
■ Vehicle to Everything (V2X)
This communication is the passing of information from a vehicle to any entity
that may affect the vehicle, and vice versa

4. ■ The original V2X standard is based on a Wi-Fi offshoot, IEEE 802.11p (part of the IEEE's
WAVE, or Wireless Access for Vehicular Environments program), running in the
unlicensed 5.9GHz frequency band. IEEE 802.11p, which was finalized in 2012,
■ V2X communication via 802.11p goes beyond line-of-sight-limited sensors such as
cameras, radar and LIDAR, and covers V2V and V2I use cases such as collision
warnings, speed limit alerts, and electronic parking and toll payments.

5. Purpose of vehicular Communication
■ V2X communication: Basically, it can focus on three kind of problems on the road,
• Fewer accident means we can have safe road
• Less congestion means we can over come the traffic jam and travel fast
• Reduce emission means green transportation

6. ■ Blind Spot Monitoring (BSM)
■ Automatic Stability Control (ASC)
■ Forward CollisionWarning (FCW)
■ Automatic Emergency Braking (AEB)
■ Lane DepartureWarning System (LDWS)

7. CommunicationTechnology
■ WLAN -based
■ Cellular -based
WIFI based 802.11p established the foundation for latency critical communication. Later on,
cellular V2X which is not only enhance safety but also bring new capabilities to users in
the era of more autonomous driving.
■ CellularV2X defines two new transmission modes that work together,
I. First, leverages existing LTE networks with ubiquitous coverage so you can be
alerted to an accident a few miles ahead or even guided to open parking space.
II. Second, transmission mode builds on LTE direct with innovations to enhance
real time information directly between the car traveling at fast speed in high
density traffic even out of coverage.

8. ■ LTE network allow massive number of devices to access theV2X.
■ On the other hand, the conventional OFDM based LTE network faces congestion
issues due to its low efficiency of orthogonal access, resulting in significant access
delay and posing a great challenge especially to safety critical applications.
Non Orthogonal Multiple Access (NOMA)
■ an effective solution for the future 5G cellular networks to provide broadband
communications and massive connectivity.
■ the applicability of NOMA in supporting cellular V2X services to achieve low latency
and high reliability.
■ To make the NOMA scheme more practical, various multi-user detection (MUD)
techniques, such as successive interference cancellation (SIC), are applied at the end-
user receivers for decoding to cope with the co-channel interference caused by
spectrum sharing among various users.

9. Non Orthogonal Multiple Access (NOMA)
■ NOMA has been proposed as a new access technique for next generation mobile
communications, supporting massive connectivity and sufficient spectrum usage.

10. ■ Two types of NOMA schemes
I. Power Domain NOMA (PD-NOMA)
II. Code Domain NOMA (CD-NOMA)
PD-NOMA
■ share the same channel simultaneously by power domain multiplexing at theTx
■ SIC can be applied at the end-user Rx users to decode the received signals
■ It smartly exploits the differences of received power levels to obtain higher spectrum
efficiency than the OMA scheme.

11. CD-NOMA (Know as SCMA)
■uses sparse (or low-correlation) spreading sequences to integrate data streams of
various users
■Each user is identified by a codebook containing multiple codewords
■one codeword is represented by the spreading sequence of which length equals the size
of the subcarrier set
■At the transmitter, bit streams of each user are directly mapped to different sparse
codewords of the corresponding codebook
■All mapped codewords are then multiplexed over the dedicated subchannels, followed
by a near-optimal detection of over-laid receiving sequences

12. NOMA Applicability to CellularV2X
NOMA-BasedV2X Unicast System Model
■ One sub-channel can be assigned to multiple pairs
■ OneV2X pair can occupy multiple sub-channels
■ The BS is capable of frequency resource allocation requiring global positioning
information
■ SIC is performed based on the decreasing channel gains of Tx users for decoding the
target signals because of Rx users suffer co-channel interference from neighboring Tx
users

13. Key Problems and Solutions of
Resource Allocation and Signaling Control
■ Considering the mobility of vehicles and complicated cross-interference caused by the
dense topology,
■ Traditional dynamic centralized resource allocation may cause significantly large delay
since the users need to send resource request messages to the BS for every data
packet.
■ Accurate Channel State Information (CSI) is hard for the BS to obtain in a mobile
environment.

14. ■ To achieve the optimal scheduling given the latency requirement and mobility
features, a new Mixed Centralized/Distributed (MCD) scheme is provided in which the
BS performs the SPS and the Tx users perform distributed autonomous power control
in each time slot
■ At the beginning of each SPS period, the BS determines how to allocate frequency
resources to the Tx users, which takes full advantage of the global position information
obtained by the BS to perform interference management.
■ Dynamic distributed power control by the Tx users is then performed to resolve the
issue of the BS not being able to obtain real-time CSI as well as to improve the rate
performance of PD-NOMA.

15. Calculation
■ indicator variable X j,k
■ sub-channel K is allocated toTx j
■ The aim at improving the number of successfully decoded signals,
■ decoding, Rate j’,k
■ the data rate of the linkTx user j’ — Rx user k, Sj
■ represents the set ofTx users with higher channel gain s3 thanTx user j over
subchannel k, and h is the slope parameter of the logistic function.
***This is a non-convex problem due to the binary variables, which can be converted into a many-to-
many matching problem with externalities***

16. Simulation Results
■ System performance of the NOMA-MCD scheme: a) PRP vs. speed of vehicles; b)
latency satisfaction ratio vs. decoding rate threshold.

17. Performance Evaluation
■ At the beginning of each SPS period, each vehicle user updates its position and
velocity information to the BS. The BS then allocates the frequency resources to the Tx
users to maximize the number of successfully transmitted messages in which large-
scale fading is considered based on predictable distance information.
■ After the centralized spectrum assignment, distributed power control coupled with Tx-
Rx selection is performed. In each iteration of the control signaling sub-slot, the Tx
users adjust their transmit power based on the feedback from neighboring Rx users.
The whole distributed power control process ends within the control sub-slot of a
transmission slot, followed by the data transmission in which Rx users can decode
received signals given the CSI obtained from the control sub-slot.

19. ■ The proposed NOMA-MCD scheme is then naturally extended to this case such that
one Rx user can receive from multipleTx users simultaneously, reducing the resource
collision and improving massive connectivity via power domain multiplexing.
■ The robustness toward data collision can then be improved along with the reduction
of retransmissions and the corresponding access delay.
Conclusion

20. ThankYou