Ergodic and Non-ergodic channel

ergodic channel

Hello,

What is the meaning of ergodic and non-ergodic channel? and what is the method to know if it is ergodic or not?

Thanks in advance
Regards

non ergodic process

A channel process is said to be ergodic if its statistical properties (such as its mean and variance) can be deduced from a single, sufficiently long sample (realization) of the process. This means that, observing many samples of a single process is statistically equivalent to observing single sample of many processes for ergodic processes.

For more information:
https://en.wikipedia.org/wiki/Ergodic_process

ergodic source

An ergodic source is one, if obserev for long period of time, will emit the sequence of souce symbol which is typical.
In this source after certain interval of time it is possible to go from any state to any state with non zero probability.

ergodic channel wiki

hi, all
we use the shannon capacity and outage capacity in different case. can anyone talk about what decides the channel is ergodic or no-ergodic. is it the propagat environment or others?

thanks

non-ergadic channel

insatiable said:

hi, all
we use the shannon capacity and outage capacity in different case. can anyone talk about what decides the channel is ergodic or no-ergodic. is it the propagat environment or others?

thanks

Click to expand...

Hi,

As many people said above, ergodic channel has a long term constant bit rate. Actually, guys who know random process will say that erogodic channel has same time and ensemble average. When we say the time average and the ensemble average, we have to begin from the observation with time. So ensemble means a set of signals observed, and time average means average for oberving time. Anyway, most of nature events (e.g channel) do not have ergodic property, but we should assume it to calculate the some results.
For example, you know, there are several channels the great have defined. The channel properties are different according to the environments, and it can be represented by the channel gain roughly, but the channel gain that we use is usually the function of time.
In the case of erogdic channel, the channel has constant capacity at the constant rate since the long term average of channel gain is constant.
However, in the case of non-ergodic channel, the channel gain is not the function of time, so that we can not say constant capacity such as shannon's.
Another important thing is the probability of the special rate. If a certain channel has the static characteristic at the special rate, or we can make such a condition(e.g. quasi-static channel), the capacity of that channel can be measured with special rate. That is outage probability.
It is all about what I know... please let me know my fault. Thanks.