Apple and Samsung dominate the smartphone market, and rumors always surround the two giants as consumers dream about the next-generation iOS or Android handset.

Both companies have massive fan-bases who are always eagerly awaiting updates to their favorite handset, whether it's Apple's flagship or Samsung's. The hugely popular Samsung Galaxy S3 is not even a year old, but rumors have already started swirling in anticipation of the next-generation smartphone, the purported Samsung Galaxy S4.

During this year's International CES tech fest in Las Vegas, smartphone manufacturers such as Sony and Huawei unveiled new 5-inch handsets sporting full-HD 1080p displays. Neither Apple's nor Samsung's current flagship smartphones sport this feature, but thing are expected to change with the next generation.

According to some of the rumors making rounds online, Samsung's upcoming smartphone will address this issue by boasting a 5-inch display with a pixel density of 440 pixels-per-inch (ppi). Samsung will also likely use the recently-unveiled octa-core Exynos 5 for its next-generation Galaxy flagship smartphone, but nothing is official yet.

Flexible, Unbreakable Screen

The purported Samsung Galaxy S4 could also pack the flexible YOUM display Samsung unveiled at CES 2013. If this proves to be true, it would mean the handset will have a virtually unbreakable screen. Competition may be tough on today's smartphone market, but a foldable, unbreakable screen could be hard to top.

1080p 

According to CNET UK, a 5-inch 1080p display is in the works, and is headed towards the upcoming Samsung Galaxy S4. While it would be a major step forward, it would not come as a great surprise. Samsung's competitors have already unveiled 1080p smartphones, and the South Korean company is not likely to stay behind.

Octa-Core 

Virtually every high-end smartphone packs powerful quad-core processors under the hood, and Samsung needs to raise the bar if it wants to stay on top. Packing its latest Exynos 5 Octa system-on-chip processor onto the next-generation Galaxy handset would likely do the trick.

Wireless Charging

Various rumors suggested that the Samsung Galaxy S4 will sport wireless charging capabilities, and a new SamMobile report claims those rumors are real. Samsung will reportedly sell a separate dock and back cover with wireless charging capabilities for the Galaxy S4 handset. The wireless charging kit will become available a couple of weeks after the handset goes on sale. The next-generation Samsung flagship device will also reportedly pack a 2,600mAh battery, compared to the Galaxy S3's 2,100mAh one. 

S Pen

The upcoming Samsung Galaxy S4 is expected to come with the S Pen stylus, which helped Samsung's Galaxy Note 2 phablet distinguish itself from its competitors. Should this rumor prove to be true, the Samsung Galaxy S4 will be the first smartphone to have such a stylus.

Camera 

Some recent reports claim that the Samsung Galaxy S4 will sport a 13-megapixel camera to match its competitors. The current model features an 8-megapixel sensor.

Name? 

Interesting fact: the number four does not appear in any of the model numbers of Samsung's phones, and that's because the number four is considered "unlucky." In Chinese and Japanese it sounds like "death," while in Korean it sounds like "kill." With this in mind, one question lingers: what name will the next-generation Galaxy flagship smartphone have? If the number four is out of the question, so is the name Samsung Galaxy S4. 

The successor to the popular Samsung Galaxy S3 is expected to make its debut at the Mobile World Congress (MWC) 2013 in February and hit the market by April or May this year. Considering the impressive track record that Samsung Galaxy devices have set, the next-generation Galaxy flagship smartphone will likely squash competition. It has some big shoes to fill nonetheless, as the Galaxy S3 sold over 30 million units worldwide in just six months after its release, but if the rumored specs prove to be true, the next-generation handset should have no problem meeting expectations.