On E-MBS with Layered Transmission

Document Number: IEEE C80216m/09_0355r1Date Submitted: 2009-01-12

Source: Debdeep Chatterjee, Furuzan Atay, Jong-Kae (JK) Fwu, Huaning Niu, Hujun YinEmail: jong-kae.fwu@intel.com

Venue: IEEE Session #59, San Diego

Base Contributions:None

Re: 802.16m-08/052, Call for Comments on 802.16m SDD (802.16m-08/003r6), Subject: EMBS Purpose: For TGm discussion and adoption of 802.16m SDD text

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Layered Transmission (MCW Transmission) using SPC

• Transmission of two types of frames using superposition coding (SPC) to support hierarchical encoding– Basic frames (B)– Additional frames (A)

• Both types of frames are MBS frames– B-frames carry “coarse” information– A-frames carry “fine” or “enhanced” information

• Need to provide a larger coverage for the basic frames– Users with good channels and successive interference

cancellation (SIC) receivers may use interference cancellation (IC) to decode the additional frames too.

• Total system capacity reflected by the sum-throughput for the two kinds of frames

System Level Simulation

• Multi-BS MBS with SFN• No HARQ• Adaptive MCS to provide:

– 95% coverage for the basic frames – 40% coverage for the additional frames

• Transmission mode: 2-stream spatial multiplexing (SM) mode

• ISD = 1.5 km• Channel Estimation: Ideal

System Level Simulation Parameters

Parameters Value

Number of Cells (3 sectors) 19

Bandwidth 10 MHz

Operating Frequency 2500 MHz

Minimum Mobile-to-BS Distance 35 m

Test Sector Centre Cell any sector

Sector Orientation Bore-Sight Pointing

BS Height 32 m

MS Height 1.5 m

Propagation Model eITU PedB

Log-Normal Shadowing Standard Deviation 8 dB

BS Shadowing Correlation 2

ISD 1500m

MS Noise Figure 7 dB

BS Antenna Gain 17 dB

CPE Antenna Gain 0 dBi

System Level Simulation Parameters (2)

Parameters Value

BS Maximum PA Power 46 dBm

Frequency Reuse Factor 1x3x1

Antenna Configuration BS: 2tx, 2rxMS: 1tx, 2rx

FFT Size 1024

Cyclic Prefix 1/8

MS Rx Combining Scheme MMSE, and MMSE-SIC

Modulation and Coding QPSK ½, QPSK ¾, 16QAM ½, 16QAM¾ , 64QAM ½, 64QAM 2/3, 64QAM ¾, 64QAM 5/6

Fast Fading Model 100% PedB 3km/h

Cyclic Prefix 1/8

Permutation type PUSC

Fast Fading Model 100% PedB 3km/h

BS and SS antenna correlation 0.0

Geometry distribution for MBSFN with Layered Transmission

100 MS/sector. Power for B-frames 20dB more than that for A-frames

100 MS/sector. Power for B-frames 10dB more than that for A-frames

• For B-frames, the interference caused by signals corresponding to the A-frames (from all the BSs, including the home-BS) is treated as noise

• For A-frames, the B-frames are assumed to have been successfully decoded, and the SINR is computed as in a typical SFN scenario

• The geometry is affected by the power allocation between the two types of frames

Throughput Performance

“X dB power diff.” = “Power for B-frames is X dB more than that for A-frames”.MCS Adaptation Target: 95% coverage for B-frames and 40% coverage for A-frames at PER of 1%

Summary

• For 1.5km ISD, the overall throughput gain over 2x2 SM with single layer transmission is about 17.7% (for 95% coverage). This assumes– Ideal channel estimation– Optimal power allocation between the two

layers– All MSs have SIC receivers

Practical Considerations• The effect of channel estimation errors (for the case of non-ideal channel

estimation) is more pronounced for SIC receivers than for non-SIC receivers

• Considerably higher receiver complexity required (need to be able to perform SIC) to be able to decode the “enhanced” layer

• The performance heavily depends on the power allocation between the basic and additional frames, and this would require at least a semi-static adaptation to cope with variations in the large-scale fading

• The percentage of MSs in the actual system with SIC capability affects the overall coverage performance

• The throughput gains over 2x2 SM with SCW decreases with ISD. Thus, for real E-MBS systems that may have large ISDs, the throughput gain may not be significant