HTC Corp, the world's No.5 smartphone maker by shipments, is widely expected to roll out four models later this month at the Barcelona Mobile World Congress, including an ultra-slim type, currently codenamed the HTC Ville, and one that uses advanced quad-core chips.

The challenge, analysts say, is to make such devices stand out in an increasingly competitive marketplace.

"It can be turned around," says Melissa Chau, Singapore-based research manager for IDC. "But the problem remains the same: How are they going to differentiate?"

The size of the problem is getting clearer. Before the Barcelona conference, analysts expect HTC to post an 11.6 percent decline in revenue this quarter compared with the last one, after a worse-than-expected decline in the fourth quarter, the first decline in two years.

The company will announce first-quarter guidance at around 0800 GMT on Monday.

"We think the company is likely to give muted 1Q shipment and sales guidance due to lackluster demand for its old products, and as most of their new projects will be only kicked off in late 1Q," said BNP Paribas analyst Laura Chen in a report.

She noted aggressive price cuts, lower economies of scale and likely inventory digestion as pressuring sales and margins this quarter. BNP expects HTC to resume sales momentum from late in the first quarter of 2012 and more than 30 percent sales growth in the first half of the year. But it won't stop year-on-year sales and earnings growth remaining in decline.

DROPPED TO FIFTH PLACE

HTC dropped to fifth place in the global league table in the fourth quarter, according to tech research company IHS, down one place from the previous quarter, as its models scrambled to compete with Apple Inc's iconic iPhone and Samsung Electronics' Galaxy range.

The Taiwanese former contract maker had a fairytale ride in 2010 and early 2011, when its shares more than tripled in the 14 months to April 2011 and sales grew four-fold in 1- years as consumers snapped up its innovative phones with their distinctive large clock numerals.

Back then, HTC was synonymous with the Android operating system: indeed, Google chose HTC to build its flagship Nexus One phone to showcase Android's features in early 2010.

But an equally rapid fall from grace saw its stock become the worst performer among global smartphone companies last year, down 42 percent. Analysts questioned its lack of new designs in the fickle and fast-changing smartphone market.

HTC has found it hard to differentiate itself as more players have entered the Android market, says IDC's Chau. The software, and increasingly the hardware, have become commoditized, forcing HTC to hunt for new ways to stand out.

"They have been differentiating by their user interface, and that worked at the beginning," she said. "But do users now buy a phone based on that?"

Meanwhile Samsung ambitiously created new segments from the high-end, with models such as its large-screen Galaxy Note, down to Android phones costing less than $200, as well as leveraging its marketing and retail networks to promote its products.

AMBITIOUS PLANS

HTC has ambitious plans for the year. It will announce four new smartphones at the Mobile World Congress on February 26, according to Barclays Capital. The HTC Ville will feature a 4.3-inch AMOLED display and an 8-megapixel camera and run on the latest version of Android, 4.0.

Other reported models include a high-end design codenamed the Edge that uses a quad-core CPU, as well as a couple of mid-range smartphones. Improved designs and performance and an absence of next new models from Samsung and Apple in the quarter will provide HTC some room to make up its lost market share, analysts said.

But challenges remain. Slowing growth in developed markets, wider distribution of Apple's iPhone 4S, especially in the United States, and a narrowing technology gap with other makers in the Android camp are all challenges HTC will have to tackle in 2012, Morgan Stanley said in research note.

HTC shares have climbed 15 percent since the beginning of this year, above the main TAIEX share index's 9 percent rise, as investors see value in the company and consider its stock oversold in previous weeks.

According to 19 analysts polled by Thomson Reuters I/B/E/S, HTC would see T$89.64 billion ($3.04 billion) in revenue this quarter, down from T$101.42 billion in the fourth quarter. Analysts also forecast a 15-20 percent decline in shipments in the quarter.

"It's going to be hard, but Android has a lot of steam behind it. Samsung leads because it's marketing hard but that doesn't mean that HTC can't reach some demographics," said IDC's Chau. She points to a doubling in the smartphone market in Asia Pacific in 2011 and a likely 40 percent growth this year.

"Not everyone wants the same device."

($1 = 29.5300 Taiwan dollars)

(Additional reporting by Jeremy Wagstaff; Editing by Jonathan Standing and Alex Richardson)

• A Permanent Economic Emergency