Mobile Domain is a free wordpress plugin to redirect WordPress blog from desktop domain to mobile subdomain and it also create Mobile XML Sitemap.
To install Mobile Domain
Login to wordpress (wp-admin).
In your admin dashboard click plugins and select Add New.
Type Mobile Domain in the search field and click Search Plugins button.
Install Mobile Domain.
After the successfully Installation click the activate Plugin link to activate the plugin.
[OR]
Download Mobile Domain wordpress plugin. Download link
Unzip and upload it to your WordPress wp-content/plugins directory.
Login to wp-admin. In your admin dashboard click plugins and activate the Mobile Domain wordpress plugin