Analog Integration in the Mobile World – Scenes From MWC

I just returned from the Mobile World Congress (MWC) in Barcelona. The weather was chilly but the city welcomed us with warm hearts. This was a perfect place to experience the dramatic impact analog integration has on our mobile world. Thought I'd share some of my observations.

The MWC buzz around new smartphones and tablets is how these mobile devices have become an extension of our individual personality and behavior. More human interface features are being integrated (i.e., analog functions), such as vivid, high-sensitivity touch screens; gesture recognition; advanced audio processing; IR-based remote control; and 3D motion sensing. To handle all the data processing, almost every new device features more powerful quad-core processors.

These features, combined with the trend toward larger batteries and the fact that device form factors aren't changing, means that with each smartphone generation, device makers must add more stuff in the same size box. And this means that more analog integration is needed to solve some very difficult engineering problems. We're talking about high-efficiency power conversion that reduces heat dissipation and extends battery runtime; accurate fuel gauging and rapid charging to optimize battery life; high-performance sound processing with echo cancellation and noise suppression to deliver an exciting audio experience; and intelligent light sensing with high-sensitivity signal conversion to enable smart power-saving gesture recognition.

There was also a tremendous amount of talk and excitement about small cell base stations and Heterogeneous Networks (HetNet). To deliver the 4G experience that we all desire, we need a mobile infrastructure in place that's capable of delivering broadband services with ubiquitous connectivity. A HetNet architecture is needed to address the 4G explosion in both number of new subscribers and demand for data throughput. To do this, the mobile operators will deploy a HetNet made up of small cell base stations to complement the Macro Cell base station footprint (the large towers).

Its important to know that indoor usage is responsible for 80 percent of all mobile voice and data traffic. And that poor indoor coverage is a major reason for subscriber churn. To improve indoor coverage and deliver high data throughput on 4G networks the base stations are moving closer to mobile users. This is basically driven by Shannon;s Limit which sets the boundary for signal-to-noise ratio and information capacity in a given channel bandwidth. One way to improve communication link signal-to-noise ratio and overcome interference from buildings and walls is to move base stations indoors.

The role of RF analog integration in small cell base stations is astounding. And RF design is the quintessence of analog design, because it demands multi-disciplinary analog design talent. These small base stations use high-performance RF transceivers that integrate every analog function needed in the radio signal chain, except RF power amplifier and band selectivity filters. For example, a device introduced by my employer integrates a 2×2 MIMO radio, which means it has two RF receiver and two RF transmitter paths in a single device.

The device also integrates an incredible number of complex analog and mixed-signal blocks, including multiple fractional-n PLL/VCO synthesizers for local oscillator tuning across 700MHz to 2.7GHz range; high-speed ADCs and high-speed DACs used to quantize and synthesize wideband I/Q signals; multiple banks of RF mixers, low-noise amps and variable gain amps in the RF signal path; as well as digital decimation, interpolation, and channel selection filters. All in a single device — now this is analog integration!

It's obvious that analog integration is playing a critical and central role in the mobile industry — from new generation smartphones and tablets to a new generation cellular network infrastructure.

4 comments on “Analog Integration in the Mobile World – Scenes From MWC

  1. amrutah
    March 15, 2013

    @Damian, Thanks for the post and really fascinated to know about the 2×2 MIMO radio on the same device.

      Once it comes to RF integration on a chip it calls for a lot of substrate analysis. Having 2 banks of RF channels will make it more worse.  Kudos to the team for pulling this off.  I am intereseted to know what kind of applications needs MIMO radio?


  2. amrutah
    March 15, 2013

    “the mobile operators will deploy a HetNet made up of small cell base stations”

    Does this mean that almost every 2nd or 3rd house (or a colony) will have a base station; something similar to what the cable-TV distributors have, a hub for each colony?

    Also, this will call for increase in cost, as the provider has to support both the macro base stations and cell base stations.  Any discussions about this in MWC??

  3. Damian Anzaldo
    March 16, 2013

    Yes these issues were discussed at MWC by the operators (i.e. provider) and base station OEM

    There are different deployment scenarios for small cell base stations depending on traffic patterns, load conditions and site characteristics. For specific indoor public areas with dense data traffic (like shopping malls, underground train stations or indoor sporting events) there will be several small cells installed to cover a given footprint and traffic load; for Small-Office-Home-Office (SOHO) or high occupancy buildings like high-rise apartment complexes in NYC, Tokyo or Shenzhen, there might be a small cell for every location like residential femto cells that are in use now. Or a higher capacity single small cell can be deployed to support several offices depending on the network topology.

    There could be an increase in operator cost but maybe not depending on the operator business model. For example an operator might have a fixed CAPEX and decides that 80% of CAPEX goes to small cells and 20% goes to macro cells. In this case there is no increase in CAPEX. Or an operator might decide to increase CAPEX (like recently announced by two major carriers one in US and other in China) and distribute the CAPEX a different way maybe 50/50-small/macro.

    In terms of OPEX it may not increase cost. For example if there is dense indoor traffic at the cell edge, the macro site can offload this to a small cell where the small cell operates at much lower RF power (ex. 5W) and the macro site can operate at lower RF output power (example 40W versus 100W). This works because the macro site no longer needs to support the indoor cell edge traffic load with high output RF power which translates to much lower kWh electric cost. The macro cell kWh cost savings can now subsidize the small cell OPEX. Also, because high ARPU subscribers are getting better QoE service then the operator revenue stream is protected or possibly improved. You can see this in recent US operator earnings reports where higher ARPU is attributed to new LTE networks.

  4. Damian Anzaldo
    March 16, 2013

    FYI – MIMO is an acronym for Multiple Input Multiple Output and is a form of spatial multiplexing. There are many applications that use MIMO for example all new 4G cellular standards like LTE, LTE-Advanced and HSPA+ require MIMO support (from 2×2 and 4×4 up to 8×8). Also Wi-Fi based on 802.11n takes advantage of MIMO. You can see this on Wi-Fi routers where there are two antennas for 2×2 MIMO. And the new WLAN standard called 802.11ac supports 2×2 and up to 8x MIMO. Even wireless backhaul systems like microwave and millimeter wave use different MIMO configurations.

    MIMO is used to increase spectral effficiency (improve bits/s/Hz). RF spectrum is a limited resource so MIMO is one communications tool that is used to deliver more network capacity. 

    Maxim Integrated has several highly integrated RF transceivers for different air-interface standards that support different forms of MIMO like the MAX2580, MAX2842, MAX2850 and MAX2851

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