Mississippi State University has a well-regarded, ABET-accredited engineering school that now offers its PhD in Computer Engineering almost completely online. Graduates from this program would gain an expanded background of both the hardware & software specializations that comprise the field of computing, and the cost ($325/hour) is less than many masters programs across the country.
Prospective students keep in mind this is a quality program, but...the application requirements here are quite strict. They admit only a limited number of students, so they rarely accept applicants that don't meet all of their criteria. When applying, definitely dot each "i" and cross each "t".
