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Re: [802.3_50G] 答复: [802.3_50G] Relating DER, BER and Q in Draft 1.2


Thanks for the pointers.

Reviewing Annex 120D:

Table 120D–8 shows DER0 is 1e-5.

There is no BER spec. Instead, Table 120D–6 specifies a PCS symbol error ratio (SER) of 1e-4.

With precoding, BER=2*DER0. Without precoding, BER=DER0. But precoding is optional.

So it looks like this was overcome by specifying SER instead of BER.

SER=10*DER0, independent of precoding.

Looks consistent.

120D.3.1.1 says:

"J4 is defined as the time interval that includes all but 10–4 of the jitter probability density distribution, ..."

120D.3.2.1 says:

 Q4 is 3.8906.

But Q4=Q(3.8906) = 5e-5 which is inconsistent with J4=1e-4.

Q4 should be 3.7 instead?

Same applies to

Clause 136:

Table 136-13 has a DER0 value of 1E-4.

136.1 specifies BER of 2.4E-4. " ... BER better than 10–4".




On 03/21/2017 02:21 AM, Yang Zhiwei wrote:

Hi Vinu,

I'm not sure how the DER0 and BER values are derived for CR, but to my understanding the basic consideration should be same with other. You can refer to "ran_020415_25GE_adhoc" for DER0 calculation. and "cideciyan_02a_1111" for PreFEC BER calculation for radom error.

As to the Q=5E-5, you can get it by Q(3.8906) there Q(x) is the Q function defined in Equation 95-1 and in mathematical also 0.5*erfc(x/sqrt(2)).

Hope a some helpful for you and may be someone can provide more details for the calculation process.

Best Regards!

Yang Zhiwei

Senior SI and Architecture Engineer, ZTE

+86 18675573560

日 期 :2017年03月18日 06:02
主 题 :[802.3_50G] Relating DER, BER and Q in Draft 1.2


Table 136-13 has a DER value of 1E-4. 136.1         specifies BER of 2.4E-4.
        calculates Q for 5E-5.

Could someone please point to the contribution(s) that relate       these values?