Evolution of Hardware Architecture in Smartphone
Wahab Ahmad, Research Scholar, Department
of Computer Science. Muhammad
Ali Mustafa, Research Analyst, Department of Computer Science
phone has become a vital component of our daily life
provide us the capability of a typical computer with absolute mobility and
small form factor. Smartphones are increasingly ubiquitous, so much so that many
users are inconveniently forced to carry multiple smartphones to accommodate
work, personal, and geographic mobility needs. Smartphones are high end mobile communication devices equipped
with computational capabilities similar that of a computer. The hardware
architecture of smartphone is significantly different from the conventional hardware
architectures. The feature and architecture of the processors is totally
different the traditional processor as these processors are developed to
cope-up with fewer energy availability with smart phones or any other ultra-portable
devices. The main challenge for hardware designers of such hybrid and complex
architectures is to increase the computational performance of the computing
unit, while keeping power constant, or even reducing it Mobile processors are
growing rapidly with each passing generation. The goal of this paper is to
review various processor architectures for mobile phones.
Smartphone development issues, smartphone processor
architecture, specialized processor architecture, hardware
smartphone is a mobile phone built on a mobile computing platform, with more
advanced computing ability and connectivity than a feature phone. The processor
architecture of conventional processor is not suitable for smartphones as
conventional processor consumes very high energy. Ever since the development of smartphones,
these devices has incorporated more and more functions. One of the big problems
is that more features mean more chips and more processing cycles, which means
higher power consumption. Because batteries do not evolve at the same speed as
the appetite of the manufacturers (and buyers) for new features, so a tradeoff
always exists between battery and mobile device.
mobile processor is a system on a chip designed to support applications that
are running in a mobile phone’s operating system. A mobile processor provides a
self-contained operating environment that provides all
capabilities required to support a mobile application, including memory
management, graphics processing and multimedia.
Hardware architecture of smart phone or any
feature phone differs significantly from the conventional processor
architecture like x86 and x64. Multiple computational units which are most
obvious part of conventional CPU can’t fit in energy starved smartphone. So, lots
or changes are required to be done in conventional CPU design and architecture
to make them suitable for smartphone or any other ultra-portable devices.
2. MOBILE PROCESSOR ARCHITECTURE TRENDS
2.1 Traditional DSP (Digital Signal Processor) Architectures
is a multiple approach to implement the smartphone hardware architecture. One
approach emphasizes programmable DSP’s, while the other approach utilizes ASIC
(Application-specific integrated circuit) techniques. definition of a digital
signal processor takes many forms. In a strict sense, a DSP is any
microprocessor that processes digitally represented signals 2. A DSP filter
for example, takes one or more discrete inputs, xin, and produces one
corresponding output, yn for n …., -1, 0, 1, 2,, and i = 1,…, N 3,
where n is the nth input or output at time n, i is the ith coefficient and N is
the length of the filter. In effect, the DSP implements the discrete-time
First Generation of mobile phone use 1G which is the form
of traditional DSP Architecture. Tightly-encoded instructions that could
specify five operations in a single instruction were initially used
to improve code density with the belief that this also
reduced instruction memory requirements, and hence
cost. Tightly-encoded instructions were also used to
reduce instruction memory bandwidth, which was of
concern when packaging was not very advanced.
Figure 1: Traditional DSP
Architecture (Harvard Architecture)
generation of mobile communications i.e. 1G systems used analog transmission
with the limitations of requiring more power for transmission and allowing
limited users 2.
of the biggest bottlenecks in executing DSP algorithms is transferring
information to and from memory. This includes data, such as samples from the
input signal and the filter coefficients, as well as program instructions, the
binary codes that go into the program sequencer. Global System for Mobile
Communications (GSM) standard evolved after first generation of mobile communication
for analog cellular networks. DSP processors form one of the most important
classes of mobile embedded processors in second generation i.e. 2G systems.
general, DSP functions are mathematical operations on real-time signals and are
repetitive and numerically intensive. Samples from real-time signals can number
in the millions and hence a large memory bandwidth is needed. It is because of
this very nature that DSP processors are created with an architecture unlike
those of conventional microprocessors. Most DSP algorithms are not complicated
and only require multiply and accumulate calculations 4. Most, if not all,
DSP processors have circuitry built and hard wired to execute these
calculations as first as possible.
architecture results in fewer cycles for executing a particular function as it
enables high memory bandwidth and multiple operand operations.
Multiply-accumulate (MAC) instructions are commonly associated with DSP
2.2 Modern DSP Architectures
modern DSP architectures, the execution pipelines were visible to the
programmer and necessarily shallow to allow assembly language optimization.
This programming restriction encumbered implementations with tight timing
constraints for both arithmetic execution and memory access. The key
characteristic that separates modern DSP architectures from classical
architectures is the focus on compellability. Once the decision was made to
focus the DSP design on programmer productivity, other constraining decisions
could be relaxed. As a result, significantly longer pipelines with multiple
cycles to access memory and compute arithmetic could be utilized. This has
resulted in higher clock frequencies and higher performance DSPs.
DSPs have become common in mobile
devices because they provide real-time operation at low power costs. Future
mobile devices have to be aligned to integrate more functions, considering
computational power requirements. Advancements in DSP lead to higher clock
frequencies as well as a reduced power consumption per MIPS for mobile phones
the digital “Revolution” of the 80’s and 90’s, when computers became available
for almost everyone and prices dropped dramatically, the development of Digital
Signal Processors and the accompanying techniques moved from the military to
industry. Digital Signal Processing has spread into a wide area of applications
like image processing, audio processing or scientific areas like spectral
analysis or earthquake analysis.
modern DSP’s, architecture can be extended by duplicating the processor cores.
Enhanced DSP’s utilizes SIMD operations, while multiple-issue DSP’s may
implement either VLIW or superscalar architectures.
Figure 2: Modern DSP
Architecture (Flow)This Simplified Diagram is of the Analog Devices SHARC DSP.
All of the steps within the loop can be executed in single clock cycle
2.3 System on Chip (SoC) based architectures
A system on a chip or system on chip (SoC or SOC)
is an integrated circuit (IC) that integrates all components of a computer or
other electronic system into a single chip. It may contain digital, analog,
mixed-signal, and often radiofrequency functions—all on a single chip
SoC is handled by a programmable processor and it
is accelerating through a function hardware. SoC based architecture have more
potential than other architecture. Highly integrated SoC’s leveraging multicore
technology has emerged for higher performance and low power designs. Low power
operation often limits the architectural choices. High throughput of VLIW
architectures in mobile devices requires a fast memory system like cache
Figure 3: System on Chip
Since the evolution of Smartphones, big SoCs are present in the
them. There’s huge requirement of memory, processing power to run a smartphone
and gpus for displays. To tackle this problem big SoCs development companies
are making high end SoCs with huge memories, buffer space, GPUs, RAM capacity
and other things.
Modern SoCs also
come with advanced (DirectX-9 equivalent) graphics capabilities that can
surpass game consoles like the Nintendo Wii. which was once known in the PC
world with licenses its graphics processors design to many SoC makers,
including Samsung, Apple and many more. Others like Qualcomm or NVIDIA design
their own graphics architecture.
Nowadays, smartphones are using SoCs which have RAM capacity of
3GB, 4GB and we have met with a smartphone having 6GB RAM just few days ago.
For most of the mobile applications, faster dual-core CPU provides better
performance than quad-core SoC’s. Future SoC’s for mobile will become more
sophisticated improving the overall performance.
Figure 4: ARM
processor Architecture (Flow)
ARM Processor introduced its first 64-bit Cortex-A50 series
processor designs as the company tries to preserve its dominance in smartphones
and tablets while catching up with Intel in servers. The new ARM processors,
Cortex-A57 and Cortex-A53, deliver higher performance at either the same or
lower power levels compared to ARM processors today. The improved performance
is key with mobile devices handling applications such as video and servers
processing an increasing number of Web transactions.
More importantly, the processors deliver
64-bit support, which enables a new range of hardware capabilities including
more memory. The new processors also boast virtualization support, error
correction, security capabilities and better floating point performance,
Forsyth said. The processor designs will offer a range of new features and
capabilities to mobile devices and servers while balancing performance with
provide chip design and instruction set customization licenses to third party
vendors like Apple, Qualcomm etc. who design their own products based on the
provided architecture. ARM licenses
architecture and processor designs to chip companies, which then make the chips
that go into tablets, smartphones and servers. The first Cortex A50-series
chips could be available in late 2013, after which companies can start making
products. Servers may be the first products to reach the market, and some chip
partners are aggressively looking at high-end smartphones and tablets
ARM dominates in smartphones and tablets, but is aiming to
make its mark in the server market ruled by x86 chips from Intel and Advanced
Micro Devices. There is growing interest in ARM servers as an energy-efficient
way to handle large numbers of Web requests such as in search or social
networks. Dell and Hewlett-Packard already offer prototype ARM-based servers
for testing to customers looking to deploy ARM servers to cut energy bills.
However, Intel is also tweaking its low-power Atom processors to work in cloud
servers and will release new Atom S-series chips for micro servers later this
The new Cortex processors are based on the ARMv8 architecture,
which was announced in October last year. The new chips will succeed the
Cortex-A15 processor, which is just reaching the market in devices such as
Google’s Nexus 10, which was announced this week. Companies including Nvidia,
Cavium and Applied Micro have licensed the ARMv8 architecture to make their own
ARM architecture is the main hardware architecture for most of
the operating systems of mobile devices such as iOS, Android, Windows Phone,
Windows RT, Bada, Blackberry OS/Blackberry10, MeeGo, Firefox OS, Tizen, Ubuntu
Touch, Sailfish and Igelle OS.
Different Mobile Phone Processors
The mobile processor has become more and more important on the
latest smartphone hardware’s specification sheets. To appreciate the importance
of mobile processors, it’s not really necessary to know the workings of each
one. This year we have seen several next generation mobile phone processors
introduced, mainly from Nvidia, Qualcomm, Apple, and Samsung. In this paper, we
would like to present some important information’s about these chips in the
mobile phones. They are currently powering and those which will be appearing
soon-to the best of our knowledge.
3.1 Qualcomm Snapdragon 600 And 800
Snapdragon is a family of mobile system on a chip (SoC) processor
architecture provided by Qualcomm. Scorpion, the original snapdragon CPU had
many features similar to ARM Cortex-A8 core based on ARMv7 instruction set, but
with an added advantage of higher performance utilizing SIMD operations.
Qualcomm dominates mobile processors, and these two Snapdragon processors will
likely be in many of the Smartphone released during the year 2013.
The quad-core Snapdragon 800 never made its debut until the end
of this year, but it was worth the wait. Its features include Ultra HD
resolution video recording and streaming to Ultra HD external displays, cameras
with up to 55 megapixels and a clock speed up to 2.3GHz. The first Snapdragon product to be made available to
consumer device manufacturers was the QSD8250, which was released in November 2007.
It included the first 1 GHz processor for mobile phones.
3.2 Qualcomm Snapdragon 200 And 400
processors are designed to deliver a balance of value and performance,
including robust connectivity and better battery life for entry level
The 200 series is
used for the low-end smartphones. These phones have the bare minimum
specification required for a device to run, for example – 4GB ROM, 1 GB RAM.
series processors are made to allow smooth navigation and switching between
apps while supporting vibrant HD visuals and premium multichannel audio.
processors are designed to deliver the performance, connectivity and battery
life that consumers expect in high volume smartphones,
Snapdragon 400 series are mainly used for budget smartphones. The
Snapdragon 410 was Qualcomm’s first 64-bit mobile SoC and features an Adreno
306 GPU, Cat 4 4G LTE and up to 13Mp cameras.
The Snapdragon 450
being the latest one in the series offers a bunch of improvements like Adreno
506 GPU, X9 LTE Cellular modem, full HD video capture @ 60 fps, etc.
The dual-core Snapdragon 400 can run at a speed of 1.7GH and has
4G connectivity, and an Adreno 305 graphics chip, while the Snapdragon 200 can
reach only upto 1.4GHz and has a basic Adreno 203 graphics processor.
3.3 Intel Atom Z2580 Clover
recent developments in mobile communication technology show the importance of
mobile phone processors in the handsets. We are very much aware of the
existence and capabilities of normal and extended CPU in a system; but
unfortunately, most of us don’t have much idea regarding the mobile phone
of power consumption and energy conservation plays a vital role in ultra-portable
mobile devices. The size of the smartphone or size of any other ultra-portable
device also plays a major role in its computational and energy efficiency
Different vendors are working towards the development of more
power efficient mobile processor architectures by looking at the future of
mobile computing. All the modern mobile processors are basically ARM-based,
designated with fancy names by different cellular companies. Processors for
future mobile devices must still work with low-power, but will incorporate a
DSP core and a general-purpose core, plus additional special circuits, in a
With newer versions of mobile CPU’s, we will have more
powerful Smartphone with new GPU cores, memory interfaces, and many more
advanced features. Future mobile SoC’s will explore next generation processor
architecture to improve the device performance. The architecture of mobile
devices has been, until now, voice-centric. Special
processors, DSPs, are used to process audio data in real
time, providing the encoding/decoding and processing capabilities needed.
Mobile processing unit manufacturers are working hard to develop
powerful cell phone devices. To support next-generation data-centric mobile
devices, processor architecture has to be designed considering new approaches.
Still, the development in mobile processors is driven by factors such as
low-power consumption, user interface performance, time to market, etc.
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