Dedicated resources allocation for direct communications in IEEE n Document Number: IEEE C802.16n-10/0051r2 Date Submitted: Source: Young-Ho Jung Korea Aerospace University Sungcheol Chang, Eunkyung Kim, Sungkyung Kim, Hyun Lee, Chulsik Yoon ETRI * Re: Call for contributions for n AWD Base Contribution: N/A Purpose: To be discussed and adopted by TG802.16n Notice: This document does not represent the agreed views of the IEEE Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Copyright Policy: The contributor is familiar with the IEEE-SA Copyright Policy. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and..html#6sect6.html#6.3 Further information is located at and.

Direct Communication Scenarios S1: HR-MS forwarding to network (IEEE n network reference model  ) –Case 1: HR-MS S/S is outside of HR-BS coverage –Case 2: HR-MS S/S is within the coverage of HR-BS S2: Local connection between HR-MSs (IEEE n network reference model  ) –Case 1: one of HR-MSs is outside of HR-BS coverage –Case 2: all HR-MSs are within the coverage of HR-BS –Case 3: all HR-MSs are outside of HR-BS coverage HR-MS S/S: HR-MS with sourcing and sinking of data Forwarding HR-MS: HR-MS with fowrding function

Candidate Options for Direct Communication Resources O1: some of DL resources are allocated for direct communications –TDM –FDM O2: some of UL resources are allocated for direct communications –TDM –FDM

Interference scenarios for direct communications Inter-Carrier Interference (ICI) and Inter-Symbol Interference (ISI) –Condition: When the signals from different transmitters arrive with a time difference larger than CP size –Examples HR- BS HR-MS (RF) HR- MS AMS Utilize different subcarriers of UL resources HR- BS HR-MS (RF) HR- MS AMS Utilize different subcarriers of DL resources

Interference scenarios for direct communications ADC bit resolution reduction due to large RMS value in time domain (see Appendix for numerical analysis) –Condition: When receiving signals, if some signals from adjacent transmitters (even if orthogonal subcarriers are used) are received with very large power. –Examples HR- BS HR-MS (RF) HR- MS AMS Utilize different subcarriers of UL resources HR- BS HR-MS (RF) HR- MS AMS Utilize different subcarriers of DL resources p-p for ADC Direct-comm. signal Cellular UL signal p-p for ADC Direct-comm. signal Cellular DL signal

Interferences for Direct-mode Resource Allocation Options (HR-MS forwarding) HR-MS  AMS or MS HR-MS  HR-RS or HR-BS AMS or MS  HR-MS HR-RS or HR-BS  HR-MS S1 Case 1 DL (O1) TDM---- FDM Reduction of ADC bit resolution for adjacent active AMS or MS -- - (time synchronization is required) UL (O2) TDM- - (time synchronization is required) - (time synchronization is required) - FDM-- Reduction of ADC bit resolution of HR-MS due to adjacent active AMS or MS - Case 2 DL (O1) TDM---- FDM Reduction of ADC bit resolution for adjacent AMS or MS --- UL (O2) TDM---- FDM-- Reduction of ADC bit resolution of HR-MS due to adjacent active AMS or MS - S1: HR-MS forwarding to network Case 1: HR-MS S/S is outside of HR-BS coverage, Case 2: HR-MS S/S is within the coverage of HR-BS

Interferences for Direct-mode Resource Allocation Options (Local Connection) HR-MS  AMS or MS HR-MS  HR-RS or HR-BS AMS or MS  HR-MS HR-RS or HR-BS  HR-MS S2 Case 1 DL (O1) TDM---- FDM Reduction of ADC bit resolution for adjacent active AMS or MS -- - (time synchronization is required) UL (O2) TDM- - (time synchronization is required) - (time synchronization is required) - FDM-- Reduction of ADC bit resolution of HR-MS due to adjacent active AMS or MS - Case 2 DL (O1) TDM---- FDM Reduction of ADC bit resolution for adjacent AMS or MS --- UL (O2) TDM---- FDM-- Reduction of ADC bit resolution of HR-MS due to adjacent active AMS or MS - S2: Local connection between HR-MSs Case 1: one of HR-MSs is outside of HR-BS coverage, Case 2: all HR-MSs are within the coverage of HR-BS

Interferences for Direct-mode Resource Allocation Options (Local Connection) HR-MS  AMS or MS HR-MS  HR-RS or HR-BS AMS or MS  HR-MS HR-RS or HR-BS  HR-MS S2 Case 3 DL (O1) TDM - (ICI and ISI to cell edge AMS or MS)* --- FDM - (ICI and ISI to cell edge AMS or MS)* --- UL (O2) TDM-- - (ICI and ISI from cell edge AMS or MS)* - FDM-- - (ICI and ISI from cell edge AMS or MS)* - S2: Local connection between HR-MSs Case 3: all HR-MSs are outside of HR-BS coverage *: If there is any AMS or MS within the HR-BS coverage near the HR-MS pair (outside of HR-BS coverage), ICI and ISI can be taken effect due to timing synchronization mismatch, however, the possibility is very little.

Proposed text for IEEE802.16n AWD Frame structure supporting direct communication For direct communication, some of downlink and uplink resources shall be dedicatedly assigned for direct communication.

Conclusion If exclusive resources are allocated for direct communication, there is no severe interference. If TDM type resource segmentation is used, there is no interference at all. If FDM type resource segmentation is used, degradation of ADC resolution problem can be happened, however, its possibility is very little, and the effect of ADC resolution reduction is not severe. (DL resource: HR-MS  AMS or MS, UL resource: AMS or MS  HR- MS)  If dedicated resources are allocated for direct communication, all combinations of TDM/FDM and DL/UL resources can be considered as resource segmentation option for direct communication.

Appendix Analysis of ADC bit resolution reduction due to high power interfering signals –ADC resolution reduction at HR-MSs due to adjacent AMSs in the uplink resources is analyzed, however, the effect at the AMS due to HR-MSs in the downlink resource is identical.

Typical parameters –ADC resolution for mobile station: 12 bits (for both I/Q signals) –RMS value of AGC output = 127 RMS value of received signal is mapped to 127 of ADC output –RMS value of direct-communication signal 127*sqrt(P direct )/sqrt(P direct +P Cellular ） e.g. ） P Cellular ／ P direct ＝ 1000 (30dB ）  RMS value of direct mode signal ＝ 4.02 P Cellular ／ P direct ＝ 100 (20dB ）  RMS value of direct mode signal ＝ 12.7 P Cellular ／ P direct ＝ 10 (10dB ）  RMS value of direct mode signal ＝ 40.1  ADC bit resolution of the desired signal (direct comm.) is reduced (1/3 ~ 1/30) The effect of ADC bit resolution reduction

Interference due to ADC bit resolution reduction –ADC bit resolution reduction  incensement of quantization noise in time domain  inter-carrier interference (ICI) in the frequency domain –Quantization error (variance) =  2 /12 –  ＝１／ RMS direct 4.02 (-30dB), 12,7 (-20dB), 40.1 (-10dB) –Upper bound of SINR SINR (dB) = 10log 10 (1/Quantization error variance) = 10log 10 (12/  2 ) Assumptions for performance analysis –FFT size = 1024 –Dedicated resources are allocated for direct communication –RMS value of AGC output = 127 P direct /P Cellular Theoretical bound Simulation results -10dB42.9dB -20dB32.9dB -30dB22.9dB The effect of ADC bit resolution reduction

Power of direct comm./ power of cellular interference = -20dB Power of direct comm. / power of cellular interference = -30dB The effect of ADC bit resolution reduction - constellations blue o – floating point, red x – with the effect of ADC bit resolution reduction)

SNR vs. SINR (effect of ICI due to ADC resolution reduction) –Power of direct comm. power/ power of cellular interference = -20dB –Performance loss at the High SNR range (marginal loss less than SNR = 15dB) - Power of direct comm. power/ power of cellular interference = -30dB The effect of ADC bit resolution reduction - SINR reduction due to ICI (inter-carrier interference)