Sony just released the Xperia Z3 as one of its premium phones and already, the company is reportedly working on an Xperia Z4 slotted to be unveiled in March 2015.

The new Sony Xperia Z4 is speculated to incorporate major improvements from the current features of the company's current flagship device, the Z3. The Z4 is expected to come with a 5.5-inch display with QHD 1440 x 2560 resolution whereas the Z3 currently sports a full 5.2-inch HD display.

The Xperia Z4 has also been rumored to be powered by a 64-bit octa-core Snapdragon 810 processor clocked at 2.8 GHz, and the new Adreno 430 GPU. It will also include 4 GB of RAM and 32 GB of storage, a major upgrade from previous Xperia devices with which storage options are typically available at 16 GB.

In addition, as an improvement from the IMX220 camera sensor used in the Xperia Z3, the upcoming Z4 is expected to have a new and better sensor, possibly an Exmore RS CMOS, and will come with a 27-megapixel rear camera and 10-megapixel front snapper.

For the first time among Xperia devices, the Z4 is also rumored to support Cat. 6 LTE connectivity, aside from Bluetooth 4.1. The Android 5.0 Lollipop OS will also be integrated into the device.

While Sony is yet to reveal major details about the upcoming Xperia Z4, the current Z3 has already raked in positive reviews for its special features, such as being waterproof, enabling users to take photos underwater, and editing these images with various Xperia camera apps.

Thanks to its support for the PS4 Remote Play, dynamic display, and noise-cancelling capabilities, the Z3 has also received praises for allowing and enhancing the PS4 gaming experience.

Other devices in the Z3 lineup, including the Z3 Compact and Z3 Tablet Compact, have also garnered positive reviews for their features, specs and performance.