There are 3 Ways of adapting the website for mobile devices
1. Responsive design
2. Dynamic serving
3. Different URL
The first two do not require any redirection to the mobile version. The third requires.
Which method of the three better - theme holivarnaya, so I will limit myself to references to Habr:
Comparison of methods of creating mobile versions of sites
Whether to do a mobile version? 5 common Pro...
And the recommendations of the search engines how to make a mobile version of the website and the correct redirection to the mobile version:
Indexing by Yandex mobile version of the site on ...
Sites for mobile devices, recommendations Yandex
Recommendations Google if mobile/desktop vers...
In short - Google for 3rd method recommends that you register tags:
On the page for computers (http:// www.example.com/page-1) add the following code:
<link rel="alternate" media="only screen and (max-width: 640px)"
On the mobile homepage (http:// m.example.com/page-1) abstract should be:
<link rel="canonical" href="http://www.example.com/page-1">
Yandex recognizes the mobile version on subdomain, but does not recognize in a separate folder:
If the mobile version of the site located in a subdirectory of the main site, indexing Yandex robot will not be able to index the data and to recognize the website mobilephone. Use responsive design or dynamic layout