Sony Xperia Z3 Series devices
Sony Unveils New Z3 Series Xperia Smartphones, Tablet, Smart Wearables at IFA 2014Sony Mobile

There is lull around the Sony Xperia Z4 after months of hype, sparking off speculations whether it would be launched at the Mobile World Congress 2015 (MWC 2015) to be held in Barcelona from 2 to 5 March or delayed by a few weeks.

It was earlier reported that Sony's flagship smartphone would be unveiled on the first day of MWC 2015 along with Xperia Z4 Ultra but nothing much has been talked about these devices off late with focus shifting to the Xperia Z4 Tablet and the Xperia M4.

Interestingly, a report by XperiaBlog has claimed that Sony might not announce its flagship smartphone, the Xperia Z4 at the MWC 2015 but release it this summer. Leaked email from Sony executive had earlier hinted that the device could be released between May and November this year. 

Meanwhile, reports have suggested that the Sony Xperia Z4 would have at least six feature upgrades over the Xperia Z3.

1) Display: There are conflicting reports on the screen size of Sony's flagship smartphone with some reports suggesting that it would sport a 5.2-inch IPS LCD capacitive touchscreen with 2560 x 1440 pixels (565 ppi pixel density), while others claim that it would be seen in either 5.4-inch or 5.5-inch screen. On the other hand, the Xperia Z3 has a 5.2-inch IPS LCD capacitive touchscreen with 1080 x 1920 pixels (424 ppi pixel density).

2) Processor: The Xperia Z4 is expected to be powered by Qualcomm Snapdragon 810 processor clocking at 1.5 GHz, while its predecessor has Qualcomm Snapdragon 801 that clocks at 2.5 GHz.

3) Operating System: The Xperia Z3 runs on Android 4.4.4 KitKat (planned upgrade to Android 5.0 Lollipop), while its successor is expected to come running with Android 5.0 Lollipop.

4) Memory: The next-generation smartphone is expected to come packed with 32/64 GB internal memory, 4 GB RAM and microSD up to 128 GB, while its predecessor has 16/32 GB internal storage, 3 GB RAM and microSD up to 128 GB.

5) Camera: The Xperia Z4 also expected to have a 20.7 MP main camera like the Xperia Z3 but it is expected to have a superior front snapper with 5 MP compared to 2.2 MP seen in its predecessor.

6) Battery: The Xperia Z3 is powered by non-removable Li-Ion 3100 mAh battery, while its successor is expected to come with a 3420 mAh battery.