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The long-awaited rollout of 5G should help make this year's edition of the world's biggest mobile industry trade show a particularly interesting one.

Here are some of the top things to keep an eye on as the Mobile World Congress (MWC) unfolds in Barcelona, Spain from Sunday to Thursday.

This column has been updated to discuss the unveiling of Microsoft's HoloLens 2 headset.

1. 5G Phone Launches

Samsung (SSNLF) got this ball rolling at its Feb. 20 event in San Francisco when it unveiled the Galaxy S10 5G as well as a foldable phone (the Galaxy Fold) that will be available via both 4G and 5G models. Look for many rival Android OEMs to unveil their own 5G phones at MWC -- LG and Sony (SNE - Get Report) are expected to show off their first 5G phones, and several Chinese phone makers might do the same. Most, if not all, of the phones, will use Qualcomm's (QCOM - Get Report) Snapdragon X50 5G modem.

Given that the first devices supporting a next-gen radio interface have historically been priced at a premium and had so-so battery lives, it's worth paying attention to what the first 5G phones will sell for and what kind of battery life their creators expect from them. Samsung, notably, hasn't yet revealed either detail about the Galaxy S10 5G; it's quite likely the phone will cost more than Samsung's Galaxy S10+, which starts at $999.

2. Foldable Phones

In addition to Samsung, a number of Chinese OEMs have been working on foldable phones, and some of them are expected to be revealed at MWC. Huawei is expected to reveal a foldable device known as the Mate X, and Xiaomi could unveil the foldable phone depicted last month in an intriguing teaser video.

Like Samsung's Galaxy Fold, which is priced at $1,980, the foldable phones unveiled at MWC will likely be costly and available in limited volumes. In the near-term, foldable phone launches are less about creating a mass market than about laying the foundations for one down the line -- specifically, by creating buzz among early adopters and giving major app developers an incentive to work on better supporting foldable displays.

3. Other Phone Hardware Innovations

With global smartphone sales continuing to slump, smartphone makers also have good reason to commercialize new hardware technologies that are ready to be deployed in relatively cheaper, high-volume phone models.

LG, for example, is launching a phone featuring a vibrating OLED display that doubles as a speaker. China's Oppo plans to show off a phone with a 10x optical zoom. And several OEMs (including Samsung, via the Galaxy S10 5G) are looking to launch phones with front and/or rear cameras that sport 3D depth-sensing systems that can potentially do things such as enable background blur effects (bokeh) and create 3D models of captured objects that can be used by augmented reality apps. For its part, Apple (AAPL - Get Report) , whose TrueDepth front camera system arrived in 2017, reportedly plans to launch iPhones with 3D rear camera systems and 5G modems in 2020.

4. 5G Network Announcements and Demos

Phone makers, network equipment makers, chip suppliers and carriers will all be eager to show off what 5G networks, which among other things can deliver multi-gigabit peak download speeds, significant network capacity increases and connections with very low latency, are able to deliver. Look for network demos covering everything from smartphones to AR/VR headsets to IoT devices and home broadband connections.

In addition, some major carriers could share new details about how their 5G network rollouts are expected to progress. Ahead of MWC, Verizon  (VZ - Get Report) announced it plans to launch 5G in 30 U.S. cities this year.

5. A New Microsoft HoloLens Headset

In early 2016, Microsoft  (MSFT - Get Report) began shipping its first-gen HoloLens augmented reality headset (Microsoft prefers calling it a "mixed reality" device). It features a fairly limited field-of-view (FOV), is meant primarily for indoor use and (with the device aimed at developers and corporate early adopters) has sported a $3,000 starting price, with a commercial version going for $5,000.

On Sunday, Microsoft unveiled the HoloLens 2 at a Barcelona event. Among other things, the second-gen HoloLens packs more processing power and a better camera, has a revamped user interface, is more comfortable to wear, supports eye and hand-tracking and has a higher-resolution display with an FOV that's twice as large as its predecessor's.

However -- defying expectations that Microsoft would charge much less for its second HoloLens than it did for its first -- the HoloLens 2 is priced at $3,500. Microsoft, perhaps recognizing the competitive strengths that Apple and Alphabet/Google (GOOGL - Get Report) have in consumer AR thanks to their possession of the world's dominant mobile platforms, is aiming the HoloLens 2 squarely at businesses. The company is also hoping to sell complementary business apps and cloud services to HoloLens 2 buyers.

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6. Connected Cars

Cars have become a pretty big deal at the CES trade show, and -- as mobile chip suppliers and carriers turn to the automotive market to help grow their top lines -- they're also becoming more prominent at MWC. Companies will be eager to show off the services that 5G networks can provide for infotainment and "digital cockpit" systems, as well as their ability to support the connectivity needs of autonomous and semi-autonomous driving systems.

And though it will take a couple of years for mass-market cars supporting the technology to arrive, look for companies to also show off potential uses for cellular vehicle-to-everything (C-V2X) systems that allow cars to communicate with each other and with radios built into nearby infrastructure objects.

7. Huawei's PR Campaign

Carriers in the U.S. and parts of Europe face growing pressure to stop deploying infrastructure gear from China's Huawei and ZTE due to perceived security, in what's a potential boon for rivals such as Nokia (NOK - Get Report)  and Ericsson (ERIC - Get Report) . In response, Huawei has begun going on the offensive, highlighting its numerous 5G engagements with carriers around the world and declaring the scope of its 5G R&D investments to be second to none.

Look for Huawei to continue its PR efforts at MWC, while perhaps getting an assist or two from carriers that remain committed to using Huawei's gear in their 5G networks. Recently, The Wall Street Journal reported the German government has made a "preliminary" decision to let Huawei participate in the Germany's 5G network build-outs.