China has the potential to be a huge market for small cells - the numbers are huge. With some 1 billion mobile subscribers, even a small course change creates an enormous industry impact. We find that while Picochip/Mindspeed dominate the 3G TD-SCDMA small cell designs, the door is open for other chipset vendors to capitalise on TD-LTE. The timescale for LTE in China remains unclear, but the huge potential to upgrade many of today's 4 million public Wi-Fi hotspots into small cells would a very tempting market for any aspiring small cell vendor.
A quick recap on the Chinese mobile landscape
China is one of the most populated countries in the world, with over 1 Billion citizens. Mobile penetration is high, and spread across three national operators:
- CMCC (China Mobile) with 722 million subscribers, running 2G GSM and 3G TD-SCDMA (a Chinese only variant of 3G).
- China Unicom with about 219 million (June 2012), running 2G GSM and 3G UMTS/HSPA (same as much of the rest of the world)
- China Telecom, with some 151 million subscribers (June 2012), running 2G and 3G CDMA
China has invested a lot in TDD mode for both 3G and 4G/LTE. The 3G TD-SCDMA hasn't been particularly successful – it has quite a few differences from the standard 3G FDD mode used everywhere else, and the only significant rollout is by China Mobile themselves. While the range of handsets/smartphones supporting it continues to grow, the iPhone and many other fashionable devices don't.
This has led to extensive deployment of carrier Wi-Fi – China Mobile alone has over 4 million public access Wi-Fi hotspots – reporting 3.83 million at end 2012. This isn't artificially boosted by large numbers of residential home Wi-Fi routers configured for open access (the FON business model), but are specifically installed/owned/operated directly by the carrier. This is a carrier grade, paid for service, available to China Mobile and roaming customers. The price per GByte of data is much lower via Wi-Fi than via cellular.
China Mobile's White Book Small Cell Specification
The operator published a kind of specification/guideline/wishlist for a small cell in 2012, stating that if any vendor can provide a product which meets it, they would buy it. The functionality includes both Wi-Fi and Cellular, but doesn't explicitly state whether it's 3G or 4G (or both). The only realistic choice of chipset for 3G TD-SCDMA today is Picochip (now Mindspeed), who dominate the market.
Partly for this reason, and partly because TD-LTE is perceived to be a larger worldwide market, many prospective small cell vendors want to focus primarily on TD-LTE.
It is said that CMCC may replace many of their current Wi-Fi hotspots with these new small cells, which could be a huge market.
When will China launch 4G/LTE services?
It's really difficult to answer this question. It's down to the regulator. Most people expect the LTE spectrum to be released during 2013, but this is far from certain. While it is a given that China Mobile will use TD-LTE, other Chinese operators aren't so keen. China Telecom have said they aren't interested in the TDD mode and said if the government forces them down that route, they would rather lease the network from China Mobile than build out their own. China Unicom is much more interested in 3G – they still have the option to upgrade to 3G HSPA+ and have less pressure to adopt 4G as quickly.
This isn't holding back TD-LTE though, China Mobile has continued to invest heavily in TD-LTE and are said to have plans to deploy as many as 200,000 LTE capable macrocells even before the licence is awarded. They are in the process of procuring that amount of basestation equipment. The technology is already in large scale trials throughout many provinces across China, and is also being used for wireless backhaul of many commercial Wi-Fi hotspots.
The maturity of TD-LTE small cell products
It's difficult to say there are any truly commercially useful small cell products available for TD-LTE today, although several vendors have advanced prototypes. For example, Alcatel-Lucent demonstrated a live call using their product (based on Mindspeed chipset) last year. Traditional DAS vendors, such as Comba, and mainstream basestation vendors, such as ZTE, have been showing TD-LTE small cells on their exhibition stands for some time, but it's difficult to be certain how ready these are for full scale commercial rollout.
Fibre is widely available to larger buildings across China – apartment blocks, shopping malls, enterprise/offices. This would likely be used for most (non residential) indoor small cells. Outdoor Metrocells are likely to need wireless backhaul to the nearest hub.
Special technical requirements for TD-LTE
TDD mode requires that all cellsites – small cells and macrocells – are tightly co-ordinated to transmit and receive at the right times. This mandates not just very accurate frequency synchronisation, but also phase timing. The choices are really between GPS (which is difficult to receive the signal indoors) and IEEE 1588v2.
It seems less likely that some of the LTE-Advanced features, such as Carrier Aggregation or Co-ordinated MultiPoint (CoMP) will be introduced from the outset. Some vendors have/can demonstrate aspects of these features, but it is though the device eco-system may take some time to catch up. There are also plenty of issues to work through including voice (Voice over LTE), which we can see both Korean and North American operators have not yet fully overcome.
My thanks to Calvin Wang, webmaster of www.FemtoChina.com, for providing much of the content for this article.