Resource Allocation for Full-Duplex Communication and Ne - PowerPoint Presentation

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 Resource Allocation for Full-Duplex Communication and Networks

Zhu HanDepartment of Electrical and Computer EngineeringUniversity of Houston, Houston, TX, USABased on Tutorial with Dr. Lingyang Song, Beijing UniversitySlides are available at : http://wireless.egr.uh.edu/research.htm Slide2

Table of ContentBasic of Full-duplex CommunicationsFull Duplex Crosslayer Design

Full Duplex Cognitive Radio: Listen and TalkFull Duplex RF CSMA/CDFull Duplex HetNetResource Allocation SummaryConclusionsSlide3

2015

2005200019952010Cellular Phone Technology Evolution 2G, 3G and 4G all have its distinguished technology, respectively.Backwards-compatible evolutionBut larger technology steps require revolutions:From TDMA:

to CDMA:

to OFDMA:Slide4

KPIs

1000X Capacity(Traffic and Connections)10Gbps10X Peak Data Rate(10+Gbps)10X User Rate Anywhere(100M-1Gbps)1000X Energy&Cost Reduce10X Low Latency, High reliability

But what is 5G? D2D, small cell, Massive MIMO or

full duplex

?

5-10

X Spectrum Efficiency

6 Key Performance Indicators (KPIs) for 5GSlide5

Background of Full-Duplex TechniquesTraditional half duplex: using orthogonal resourcesTime-division duplexFrequency-division duplex

ProblemsThe orthogonal resources are allocated for reception and transmission.Solutions The same resources are allocated for reception and transmissionTime-division duplexFrequency-division duplexSpectral lossFull-duplexCommsSlide6

Full Duplex IntroductionA full duplex system allows communication at the same time and frequency resources.

AdvantagesHigh spectral efficiencySame time & same frequency bandLow costReadily use the existing MIMO radiosHardware advancement, etc.: Signal of interest: Self interferenceFull duplex communicationSlide7

Main ChallengesTraditional ChallengesVery large self interference50-110dB larger than signal of interestDepending on inter-node distanceADC is the bottleneckLimited dynamic range: saturation distortion.Limited

precision: signal of interest is less than noise.1 bit ADC is 6 dB in SNRSelf interference costs 8-18 bitsNeed to reduce interference before ADCFig. 6 Very large Self interferenceSelf interferenceReceived signalSignal of interestFig. 7 Signal after quantizationSlide8

Self-interference CancellationSelf interference channelPassive antenna propagation suppressionActive cancelationActive analog cancelationActive digital cancelation

Pre-mixer Post-mixerSlide9

Passive Propagation CancellationMIMO systemExample, two transmitting antenna has 180 degree difference at the receiving antennaMultiple antenna for beamforming, nulling and self-interference cancellation.

Challenges: Narrow band. For wideband, wavelength is different, so the cancellation is not goodSlide10

Active Analog Cancelation (2)

Post-mixerPost-mixerPost-mixerPre-mixer

ADC

DAC

x

x

Post-mixerSlide11

Active Digital CancelationConceptually simpler – requires no new “parts”Two-step cancellation:Estimate the self residual interference channel hRI through training symbolsCancel h

RIx[n] at basebandUseless if interference is too strong (ADC bottleneck)Slide12

Some existing prototypesStanford

RiceFinland Aalto UniversityBeijing UniversitySlide13

Table of ContentBasic of Full-duplex CommunicationsFull Duplex Crosslayer Design

Full Duplex Cognitive Radio: Listen and TalkFull Duplex RF CSMA/CDFull Duplex HetNetResource Allocation SummaryConclusionsSlide14

Listen-and-Talk Protocol For Cognitive Radio

We propose a novel “listen-and-talk” (LAT) protocol with the help of the full-duplex technique that allows SUs to simultaneously sense and access the vacant spectrum.Unique features of the LAT is discussed and comparison between the LAT and the conventional Listen before talk (LBT) protocol is presented.Yun Liao, Tianyu Wang, Lingyang Song, and Zhu Han, “Listen-and-Talk: Full-duplex Cognitive Radio Networks,” in Proc. IEEE Globecom’14, Austin, TX, Dec. 2014. Best Paper AwardYun Liao, Lingyang Song, Yonghui Li, and Zhu Han, “Full-Duplex Cognitive Radio: A New Design Paradigm for Enhancing Spectrum Usage,” to appear, IEEE Communications Magazine [arxiv: http://arxiv.org/abs/1503.03954]Slide15

The Listen Before Talk (LBT) Protocol

SUs sense the spectrum before transmissionSensing and transmission separate in time domainDiscontinuous transmissionDiscontinuous sensingSlide16

Motivation of Listen and Talk (LAT) Protocol

Discontinuous transmissionCan never fully utilize spectrum holes for transmissionDiscontinuous sensingInevitable collision and spectrum wasteContinuousContinuousDetect PU’s state change in no timeSlide17

System ModelOne PUNon-slottedOne FD-SU pairEach with two antennasSU1: secondary transmitterSU2: secondary receiverSlottedSlide18

Listen-and-Talk Protocol (1)

Ant1 of SU1 senses the spectrum, while Ant2 transmits if a spectrum hole is detected simultaneously.

Sensing result of one slot determines SU’s activity in the next slot.Slide19

Listen-and-Talk Protocol (2)Four states of the system:1: only the PU uses the spectrum2: only SUs use the spectrum3: neither the PU nor SUs use the spectrum – spectrum waste3-A: change of PU’s state – PU leaves in a slot3-B: sensing error – false alarm4: both the PU and SUs use the spectrum –

collision4-A: change of PU’s state – PU arrives in a slot4-B: sensing error – miss detectionSlide20

Sensing Threshold (1)The received signal in sensing varies in association with SU1’s activity.Active SU1Silent SU1Thus, the sensing threshold needs to change according to SU1’s state to achieve better sensing performance.

RSISlide21

Sensing Threshold (2)

How to set ε0 and ε1?Slide22

Sensing Threshold (3)Slide23

Sensing Threshold (4): Sensing ErrorSensing error includes two parts: false alarm and miss detection, which are defined as, respectively,Slide24

Sensing Threshold (5): State TransitionState Transition is simplified as a discrete-time Markov chain, and the probabilities that the system is at each state can be obtained.Slide25

Sensing Threshold (6): Collision RatioThe sensing thresholds are determined by the constraint of the maximum collision ratio, which is defined asSlide26

Power-Throughput Tradeoff (1): SU ThroughputThe secondary throughput isR is the rate of transmissionP

w is the time ratio of spectrum waste, defined asSlide27

Power-Throughput Tradeoff (2)

Increase with RSIThere may exist a tradeoff between secondary transmit power and the throughput, and an optimal transmit power can be derived.Slide28

Adaptive SwitchingComparison of the spectrum usageAdaptive switching of the two protocol

Lower spectrum waste ratiounder strict constraintFull utilization of spectrum holes

Spatial correlation factor

Sensing duration / Slot lengthSlide29

Table of ContentBasic of Full-duplex CommunicationsFull Duplex Crosslayer Design

Full Duplex Cognitive Radio: Listen and TalkFull Duplex RF CSMA/CDFull Duplex HetNetResource Allocation SummaryConclusionsSlide30

Full Duplex CSMA/CDLiao Yun, Tianyu Wang, Kaigui Bian, Lingyang Song and Zhu Han, “Decentralized Dynamic Spectrum Access in Full-Duplex Cognitive Radio Networks,” IEEE International Conference on Communications (ICC), Best paper award

, London, 2015.Yun Liao, Kaigui Bain, Lingyang Song,and Zhu Han, “Full-duplex MAC Protocol Design and Analysis," appear, IEEE Communications Letters Yun Liao, Kaigui Bian, Lingyang Song and Zhu Han, “Full-duplex WiFi: Achieving Simultaneous Sensing and Transmission for Future Wireless Networks,” ACM Mobihoc (poster), Hangzhou, China, 2015. Roundabout example for CSMA, CSMA/CD and Aloha RF half duplex can only use CSMA Full duplex enable CSMA/CD Performance gain when traffic is highSlide31

Full Duplex Radom Access MAC in CRNsSensing with FD: With FD techniques, SUs can keep sensing during transmission. Contention window: determine the optimal backoff length.

Handling the RSI: the RSI results in false alarm and miss detection problems.Slide32

Table of ContentBasic of Full-duplex CommunicationsFull Duplex Crosslayer Design

Full Duplex Cognitive Radio: Listen and TalkFull Duplex RF CSMA/CDFull Duplex HetNetResource Allocation SummaryConclusionsSlide33

FD HetNet System Model33Single cell FDD OFDMA

Two-tier network with base station (BS) and femto cell access point (FAP)MIMO is equipped in BS and FAP.Option to either connect to BS or one of SAPs Constrained by a maximum transmission power Slide34

Resource Allocation for FD HetNetCompared with resource allocation in HD-HetNetMode selection and connection selectionOther resources such as power and channels

34Slide35

Numerical Results and intuition Bias: connection to FAP and BSBackhaul constraintSwitch between HD and FDHuman brain is full duplex, but sometime it is better to be half duplex…35Slide36

Table of ContentBasic of Full-duplex CommunicationsFull Duplex Crosslayer Design

Full Duplex Cognitive Radio: Listen and TalkFull Duplex RF CSMA/CDFull Duplex HetNetResource Allocation SummaryConclusionsSlide37

Resource Allocation Problem Summary (1)Mode SwitchHalf-duplex radio Due the limited size of transmitter and receiver, many wireless communication systems suffer from the spatial correlation which degrades the performance gain of HD mode.Full-duplex radio It allows a node to send and receive signals at the same time in the same frequency band. However, it is practically impossible to have perfect self interference cancelation, and thus, the amount of RSI greatly affects the performance of FD system.As a result, in some scenarios, the HD mode may outperform the FD mode

for certain RSI values.This motivates the adaptive mode switching between the FD and HD modes based on the RSI and channel conditionsSlide38

Resource Allocation Problem Summary (2)Power Controldue to RSI, power control algorithm needs to be properly redesigned in order to maximize system performance of all users.FD-MIMO: The antennas at the FD node are divided into transmit and receive antenna setsWater-filling power allocation can be applied at the transmit antenna set to maximize the sum rate based on individual power constraint.FD-Relay: In FD-Relay networks with individual power constraint at each relay, the relayed signals are corrupted by the RSI, Power allocation can be considered to reduce RSI subject to total and individual power constraintsSlide39

Resource Allocation Problem Summary (3)Power ControlFD-OFDMA: for FD-OFDMA with one FD BS and HD multiple users, uplink (transmit) and downlink (receive) users are paired to communicate with FD BS at the same time. The transmit power can be allocated at the BS side with total power constraint by splitting the power among all he subcarriers for different user pairs. At the user side, power control needs to take into account the inter-user distance among the transmit-receiver user pair.FD-HetNet: Similar to FD-OFDMA, the power control can be performed for the FD BS and

femtocell access points (FAPs) and HD users in FD-HetNet to optimize the network performance. However, both the inter-cell interference and RSI need to be considered jointly in optimizing the overall network performance.Slide40

Resource Allocation Problem Summary (3)Transmit Beamforming: The robust transmit beamforming algorithms can improve the signal strength at the receiver side, and meanwhile reduce the self interference subject to various design criteria.FD-MIMO: the transmit antenna set at each FD nodes can perform beamforming

to simultaneously transmit information and reduce the interference to its own received signals FD-OFDMA: The FD BS is equipped with multiple antennas, consisting of transmit and receive antenna sets, while the users only operate in the HD transmission mode due to hardware constraint. The BS can construct beamformer to support multiple users in the downlink while maximizing the received SNRs at BS by minimizing the RSI.Slide41

Resource Allocation Problem Summary (4)Link SelectionFor a FD communication system, each antenna can be configured to transmit or receive the signals. This will create multiple possible virtual links between two nodes, with one virtual link representing the channel from a transmit antenna of one node to a receive antenna of the other. An important question arisen is how to optimally select the link for each direction to optimize the system performance.Antenna selection in FD-MIMO systemsJoint antenna and relay selection in FD-Relay systemsCoordinated multiple point transmissionSlide42

Resource Allocation Problem Summary (5)Subcarrier AllocationIn a FD-OFDMA network consisting of one FD BS with Nf subcarriers, Nu uplink users, and Nd downlink users,a fundamental challenge is how to pair uplink and downlink users, and allocate subcarrier across these user pairs

;The subcarrier allocation involves allocating the different subsets of subcarriers to different users taking into account the RSI at the BS and the co-channel interference between the uplink and downlink users within each user pair.In FD-Relay networks, consisting of multiple source and destination nodes, and FD relay nodes using OFDM transmission, the corresponding subcarriers should be also properly allocated at the relay for different source-destination pairs.Slide43

ConclusionsThis tutorial presented the recent development of FD bascis and discussed representative FD communications: FD CRN, FD CSMA/CD, and FD-HetNet networks. The associated resource allocation problems are discussed:e.g. mode switch, power control, link selection and pairing, interference-aware beamforming, and subcarrier assignment. A few examples on FD resource allocation are illustrated:FD communication is very promising, which enables many potential future research applications, e.g.,

FD MIMOFD Relay networksFD Two Way RelayFD D2DFD OFDMSlide44

Useful info for Research on FD Comms Full-duplex communication websitehttp://wireless.pku.edu.cn/home/songly/fullduplex.htmlTutorial and survey, books, technical papers, standardization…

BooksYun Liao, Tianyu Wang, Lingyang Song, and Zhu Han, “Listen-and-Talk: Full-Duplex Cognitive Radio,” in contract with SpringerBieft.Lingyang Song, Risto Wichman, Yonghui Li, and Zhu Han, “Full-Duplex Communications and Networks,” in contract with Cambridge University Press, UK.TutorialsLingyang Song and Zhu Han, “Resource Allocation for Full-Duplex Wireless Communication and Networks,” IEEE International Conference on Communications (ICC), London, UK, Jun. 2015Lingyang Song and Zhu Han, “Full-Duplex Wireless Communication and Networks: Key Technologies and Applications,” IEEE International Conference on Communications in China (ICCC 2014), Shanghai, China, Oct. 2014Slide45

Slides are available at :

http://wireless.egr.uh.edu/research.htm Thanks for your attending!