Nokia’s tablet strategy was in the spotlight again, following speculation that the company has a device known as Sirius in the pipeline.

While the company has (unsurprisingly) been rumoured to have a tablet in the works for a while, this week The Verge said that the recovering device maker is set for a launch “shortly”.

According to speculation, the new tablet will have a design which “more closely resembles Nokia’s Windows Phone products”, suggesting a set of brightly coloured polycarbonate devices will be available.

It is said to be thinner and lighter than Apple’s iPad, with full HD display. It would be powered by a Qualcomm Snapdragon 800 processor, and include LTE connectivity.

Also mooted was a peripheral keyboard which includes a battery, to provide additional power for the device.

But there is one significant potential fly in the ointment: it is reported to use Microsoft’s Windows RT platform, which has so far failed to see any significant momentum.

Windows RT, which is designed for tablets which use processors based on an ARM architecture, does not offer app compatibility with either the Windows 8 platform for PC or the Windows Phone 8 platform for smartphones.

Apps for Windows RT, therefore, have to be specifically written for the platform and made available through Microsoft’s own store.

This has created something of a vicious circle for Windows RT: without having a significant number of users, its appeal to developers is limited. But without developers writing apps for the platform, the appeal to users is also reduced.

To date, Windows RT tablets have also been premium-priced, and the Nokia device looks set to follow a similar path. But this puts them into competition with Apple’s iPad line, which has the healthiest app portfolio of any tablet device proposition.

While there are some signs that Nokia is starting to see some momentum with its Window Phone 8-powered Lumia product line, the dynamics here are significantly different.

Nokia has been able to build on its strong position in the mobile phone market, having been an unchallenged number one for many years, including its brand and its relationship with operators.

It has also been able to offer Lumia devices at a range of price points, from entry level to premium, in order to target the largest possible customer base.

And the company has also created a portfolio of its own high-quality apps, which have contributed in strengthening the Windows Phone ecosystem.

Contrastingly, Nokia has no established position in the tablet market to speak of, and a number of smartphone and computer makers including Motorola, LG, BlackBerry and HP/Palm have found this market impossible to crack.

With Apple’s iPad maintaining its leadership against competition from Android device makers including Samsung, Amazon (Kindle Fire) and Google’s own-brand offering (Nexus, made by Asus and Samsung), Nokia will have an uphill battle to make significant inroads in this space.