doc.: ieee 802.11-13/1157r3 submissionyunzhou li, tsinghua univ.slide 1 feasibility of coordinated...
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doc.: IEEE 802.11-13/1157r3
Submission Yunzhou Li, Tsinghua Univ.Slide 1
Feasibility of Coordinated Transmission for HEW
Date: 2013-09-18
Name Affiliations Address Phone email Yunzhou Li Tsinghua Univ. Tsinghua Garden,
Beijing, P. R. China +86-10-62794193
Zhendong Luo China Academy of Telecommunication Research (CATR)
No.52 Hua Yuan Bei Rd., Beijing, China
+86 10 62300171
Meng Yang CATR No.52 Hua Yuan Bei Rd., Beijing, China
+86 10 62300175
Bo Sun ZTE Corporation 86 29 88724130 [email protected]
Authors:
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 2
Abstract
• This presentation discuss the feasibility of using coordinated transmission between adjacent APs for future WLAN networks.
• As a similar technique, CoMP in LTE has been introduced briefly.
• The potential gain derived from coordinated transmission has been analyzed, by comparing with LTE CoMP and coordinated transmission in WiFi and referring the experiment results.
• Some simple coordinated schemes have been introduced.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 3
Background &Motivation
• With the increase of AP density, the inter-BSS interference will be the dominant obstacle for increase of area throughput.
• It is very difficult to work well If there existed a good path between two adjacent APs due to DL-UL interference between the two APs.
• Therefore, effective technologies and strategies have been proposed to deal with inter-BSS interference in HEW.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission
The Feasibility of Coordinated Transmission
• As showed in the figure, Access Controller (AC) are widely used in operator deployed Wi-Fi networks – AC can play a role of controller of coordinated transmission
between adjacent APs
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 5
The Feasibility of Coordinated Transmission
• Enterprise is evolving towards a cloud-based model– No longer files and information are stored on local machines
• Mobile access to cloud is expected to increase with the increase of smart mobile devices.
11-13-0098-00-0wng-802-11-looking-ahead-to-the-future-part-II
Yunzhou Li, Tsinghua Univ.
September 2013
Enterprise WiFi
doc.: IEEE 802.11-13/1157r3
Submission Slide 6
Coordinated Multi-Point (CoMP) transmission and reception In LTE
• Joint Transmission (JT)– Simultaneous data transmission from multiple points (part of or
entire CoMP cooperating set) to a single UE or multiple UEs in a time-frequency resource
• Dynamic point selection (DPS)/muting– Data transmission from one point (within the CoMP cooperating
set) in a time-frequency resource
• Coordinated Scheduling/Beamforming (CS/CB)– Data for an UE is only available at and transmitted from one point
– scheduling/beamforming decisions are made with coordination among points corresponding to the CoMP cooperating set.
3GPP TR 36.819 Coordinated multi-point operation for LTE physical layer aspects
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission
doc.: IEEE 802.11-13/1157r3
Submission Slide 8
The Difference between TD-LTE and WiFi for Coordinated Transmission
• In cellular systems of TD-LTE, all the eNBs are synchronized in symbol and slot
• Whereas each AP in Wi-Fi systems decide to transmit/receive according to its situation and don’t take care of other adjacent AP’s TX/RX.– The AP will transmit if it can detect the channel and find the channel is
idle or the adjacent AP's signal is below the CCA level.
• In addition, the deployment of eNB are chosen base on well-planning, which is very different from selection of AP’s position.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission
• Besides, there is a significant difference in use of time and frequency block between cellular and Wi-Fi.
Yunzhou Li, Tsinghua Univ.
September 2013
The Difference between TD-LTE and Wi-Fi for Coordination Transmission
doc.: IEEE 802.11-13/1157r3
Submission Slide 10
Some Coordinated Transmission Schemes
• Integrated coordinated transmission mechanism with Wi-Fi networks– All the time domain resource is divided into two categories:
Coordinated TX/RX Intervals(CTRI) and Non-Coordinated TX/RX Intervals(NCTRI) which is scheduled and decided by coordination controller according to the amount of STA and their distribution
– CTRI is like the mechanism of DMA or Interrupt in computer system.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission
Some Coordinated Transmission Schemes
• Coordinated power allocation– The scheme of AP selection is one special case of coordinated
power allocation.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 12
Some Coordinated Transmission Schemes
• Coordinated frequency band allocation: similar to fractional frequency reuse in LTE
• Joint dynamic allocation of frequency and power– Which is the combining case of coordinated power allocation and coordinated frequency band allocation
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 13
Some Coordinated Transmission Schemes
• Joint Transmission based one joint precoding– like SU-MIMO / MU-MIMO in 802.11ac
– The combing channel is and the precoding matrix is
decided based on
– MU-MIMO can be
combined to the scheme
– JT need high-resolution synchronization in time and frequency among the adjacent APs, which can be implemented by CPRI / IEEE 1588, etc.
Yunzhou Li, Tsinghua Univ.
September 2013
Coherent
1H2H
1
2JT
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H
JTH
doc.: IEEE 802.11-13/1157r3
Submission
Experiment of Multi-AP for Dense WLAN
• Each STA can detect multiple APs within its received range.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission
Experiment of Multi-AP for Dense WLAN• Strategies:
– In UL, multi-AP demodulate the STA’s signal simultaneously and check it by CRC.
– In DL, the controller chooses one AP from multi-AP as transmit point according to channel condition and load balance.
September 2013
StarEast
doc.: IEEE 802.11-13/1157r3
Submission Slide 16
Experiment of Multi-AP for Dense WLAN
• Combining with optimal physical carrier sensing(PCS), more 100% gain can be achieved in both UL and DL.
Yunzhou Li, Tsinghua Univ.
September 2013
UL DL
doc.: IEEE 802.11-13/1157r3
Submission Slide 17
Remarks on Coordination Gain
• Although only about 15% gain from CoMP in LTE can be achieved, considerable gain from simple coordinated scheme has been showed in our experiment.
• In our opinion, the possible reason is CoMP gain in LTE derived from the improved SINR for cell-edge UEs who are at low rates, so the contribution for the whole cell throughput is not considerable.
• However, the gain from coordinated transmission in WLAN is from the decrease of collision and resulting in the increase of transmission opportunity.
Yunzhou Li, Tsinghua Univ.
September 2013
doc.: IEEE 802.11-13/1157r3
Submission Slide 18
Summary
• It is feasible for integrating coordinated transmission in to WLAN for HEW by extending the role of AC.
• For analysis of potential gain, CoMP in LTE has been introduced briefly.
• Further, the difference between TD-LTE and WiFi for coordinated transmission has been summed up and some simple coordinated scheme has been introduced.
• Finally, the potential gain for HEW has been analyzed.
Yunzhou Li, Tsinghua Univ.
September 2013