Revisions Revision Comments Date R0 Initial draft template May 8th 2014 R1 May 14th 2014 R2 Update of MAC calibration and style template May 15th 2014 R3 Correction of traffic parameters in appendix 2, revised appendix 1, new VOIP models July 17th 2014 Notes on this version In R2 added: Text for box 3 of the calibration procedure Variable bit rate coding heading in Appendix 2 Table of contents and style template In R3 added: Video traffic parameter correction New text describing PHY abstraction in Appendix 1 New text for VOIP traffic Simulation Methodologies - General Concept Two types of simulation methodologies are defined to enable the assessment of the performance and gain of proposed 11ax techniques relative to 11ac, each having its own advantages: PER simulations – typically used for new PHY features for assessing to point performance
where SINRn is the post processing SINR at the n-th subcarrier, N is the number of subcarriers in a coded block and Φ is a mapping function. For PHY and integrated system simulation, the mapping function is based on received bit mutual information rate (RBIR) assuming coded-modulation. For M-QAM, the mapping function is defined as where U is a zero-mean complex Gaussian random variable with variance 1, i.e., U~CN(0,1). The lookup tables of Φ functions for different modulations are attached in appendix 3 with an SNR granularity of 0.02dB (note that high granularity is needed to accurately capture the steepness of the curve). A lookup table of AWGN PER vs. SNR for each MCS and each coding scheme (BCC, LDPC) is collected with the SNR granularity of 0.1dB for 2 reference packet lengths for BCC and 1 reference packet length for LDPC. The AWGN PER lookup tables are attached in Appendix 3. To determine if a PPDU of Nss spatial streams over N tones has been successfully received, a PHY abstraction is illustrated in the following diagram. Figure 5. RBIR based PHY Abstraction Procedure The detailed procedure of RBIR based PHY abstraction as shown in Figure 5 is: Generate (both desired and interfering) channels. Calculate the equalizer-output SINR per spatial stream for the n-th tone/t-th OFDM symbol, SINR(iss,n,t), iss=1…Nss, n=1…N, t=T0…T0+T. Equalizer is MRC if Nss=1, or MMSE if Nss>1. Definition of T0 and T are TBD. Map N×T×Nss SINRs to 1 RBIR. Reverse map 1 RBIR to 1 effective SNR. Estimate PER for based on AWGN PER lookup table. In case of BCC, PL0 = 32bytes if PL< 400bytes; or 1458bytes otherwise. In case of LDPC, PL0 = 1458bytes. Determine if this PPDU is successfully received. Appendix 2 – Traffic model descriptions
The VDI traffic is generated as shown in Figure xx. At MAC layer, arrival interval of VDI packets is generated according to exponential distribution. Figure 8: Traffic generation model Traffic direction specific parameters for packet arrival time are specified in Table 7. Step 2: At MAC layer generate VDI MSDU frame size (in bytes) for uplink and downlink transmission, respectively. For uplink the packet size is generated according to a Normal distribution. For downlink the packet size is generated with a bimodal Normal distribution. The traffic direction specific PDFs and the packet size parameters are specified in Table 7. 7: Parameters for VDI traffic model Component Distribution Parameters PDF DL UL DL UL Initial packet arrival (ms) Uniform Uniform a=0, b=20 a=0, b=20 Packet arrival time (ms) Exponential Exponential Packet size (Byte) Bimodal Normal Normal Evaluation metrics MAC throughput Latency VoIP Traffic Model