mobile communicationsbarry/mydocs/mycomp61242/mc19_lectures/... · 2019-03-26 · lecture 5: 26 mar...

COMP61242: Mobile CommsLecture 5: 26 Mar 20191

Mobile Mobile CommunicationsCommunications

Lecture Lecture 55–– Mobile TechnologyMobile Technology

COMP61242Mikel Lujan


SmartphoneSmartphone• Mobile device running a mobile operating system, with

advanced computing capability & connectivity.• Functions as mobile phone, web browser, multimedia

recorder (camera) & player, GPS, radio, alarm clock, etc.• High-res touchscreen for user interface.• Speech by accessing ‘cellular’ networks (2G, 3G, 4G).• Data from same networks: GPRS, HSPA, LTE etc.• Wi-Fi, Bluetooth, GPS & Near Field Comms (NFC). • Runs mobile apps (incl. your own).• Tablet: Large smartphone with Wi-Fi but no cellular comms.• Smartwatch: Peripheral connected by Bluetooth.


Mobile operating system: AndroidMobile operating system: Android• Android Inc. was founded in 2003 by Andy Rubin et al.• Taken over by Google in 2007.• First phone to use Android was HTC Dream in Oct 2008.• Was predated by Apple iPhone.• Android is mostly free & open-source:

– ‘Cupcake’, ‘Donut’, ‘Éclair’, ‘Froyo’, ‘Gingerbrd’, ‘Honeycomb’, ‘ICSandwich’, JellyBn, KitKat, Lollypop, MarshM, Nougat, Oreo…

• In 2010, Android became best selling platform.• In 2012, Samsung Galaxy sales hit 18 million.• In 2014, Nexus6 (with Motorola) & Galaxy5 (Samsung)• In 2017(Dec), Google released Android 8.1 (Oreo)• In 2018(Jan),Google released latest version of Chrome OS.


Mobile operating system: Mobile operating system: iOSiOS• Platform for Apple iPhone, introduced in ‘07, • Closed source & proprietary• Noted for its first use of fingered touchscreen• Initially no native 3rd party apps were allowed• In 2008, Apple introduced a new iPhone & ‘App Store’,• Allowed third party native apps using ‘iTunes’. • In Sept 2013, Apple released iPhone 5S & iOS 7.

“was most powerful smartphone ever”.• (Based on ARM 64 bit achitecture)• 2014, Iphone 6 & ‘SWIFT’ programming language• 2017, ‘iOS 11’ released in Sept.


Mobile Mobile OSOS: Windows Phone: Windows Phone

• Version 7 mobile OS released in 2010 by Microsoft.• Version 8 released in Oct ’12 • Version 8.1 released in 2014 • Version 10 released in 2015 : compatible with PC version.• Closed source & proprietary.• On Oct 8 2017, Joe Belfiore announced that work on

Windows 10 Mobile was drawing to a close.


Mobile operating sys: BlackberryMobile operating sys: Blackberry• Released in 1999 by RIM, making secure email comms

possible on wireless devices. • Famous Blackberry OS used.• Services such as BlackBerry Messenger widely used.• Closed source and proprietary.• In 2015 Blackberry Priv (Android) smartphone released.• In 2016, ceased competing in Smartphone market.• Blackberry now focusing on security software.


Other mobile operating systemsOther mobile operating systems• Bada announced by Samsung in Nov 2009.

– Replaced by Tizen• Symbian (Nokia) Widely used once, but obsolete in 2011)• Palm OS (discontinued in ’11)• Windows mobile (became Windows Phone).• Tizen (Linux-Samsung-Intel) Initially released 2012)

– version 3.0 released May 2017– may become Samsung’s alternative to Android– 2017 (May) Samsung Z4 Tizen smartphone released

• Yet other mobile operating systems exit


Ref: wikipedia/mobile operating systems (Jan’17)

7 billion people live in the world. >1 billion smartphones sold in 2016. 33% own one; > 10% have new one

Ref: wiki/mobile operating systems (Jan’18)Smartmo https://commons.wikimedia.org/w/index.php?curid=22720596

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Ref: wikipedia/mobile operating systems (Jan’17)

COMP61242: Mobile CommsLect 5: 26 Mar 201911

Current market share Current market share • According to ‘The Financial Express’, Sept 2014:

Global market share:– Android: 85 %– IOS: 11 %– Windows phone: 3 %– Blackberry: <1 %

• In USA number of mobiles >> 3 x number of landlines.- Ref: wikipedia/mobile operating systems (Jan’15)

• According to ‘Statcounter’ web-use of smartphonesovertook desktops in Nov 2016.


Smartphone anatomySmartphone anatomy• Processor & Memory • Touch screen display, buttons, mic & speaker etc.• Radio communications interface• Antenna• Battery • Techniques implemented in mobile phone or tablet:Phone calls by cellular & wifi networksAlso, data & internet access (by same networks)Sound & image capture, storage & commsBluetooth & NFCComms for navigation satellites (GPS)

RISC & Snapdragon• General purpose processors as used in PCs & lap-tops

consume too much power to be used in smartphones.• Instead use reduced instructn set (RISC) processors. • ARM is a 64-bit RISC with special instructions for digital

signal processing (DSP). • Snapdragon (by Qualcomm) is a system on chip (SoC)

designed for mobile devices.– Uses ARM instructn set (multi-core)– Has graphical processing unit (GPU), – Wireless modem, – Hardware & software for GPS, gesture recognition & video

processing.

• Competitors include Intel ATOM13

• Has system (internal) memory & external memory.• Four types of system memory:

1) Read only memory (ROM) programmed by the manufacturer to store permanent data that can never be overwritten.

2) Flash memory: can be written to but only slowly in blocks of bytes. Non-volatile meaning that contents are not lost on power-off. Does not consume energy except when being written to or read.

3) Dynamic random access memory (DRAM): can be written to & read quickly byte-by-byte. Volatile meaning that contents are lost on power down. Must be refreshed continually & so consumes energy all the time.Apps are stored in flash but must be loaded into DRAM to run.

4) Static RAM (SRAM): faster than DRAM, volatile & does not need tobe refreshed. Consumes energy only for read & write. Requires more expensive & complex transistor circuitry.

• External memory usually flash inserted as an SD card.

Smartphone Memory

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• Smartphones specs often only tell you how much internal system memory there is in total.

• They include memory for system software, flash & RAM.• System often prevents user from storing apps in SD.• Apps must be run using RAM, but how much is there?• Google’s official minimum is 832 MB of RAM.• Most Android smartphones now have 2 GB or more.• Some have 4 GB & the ‘On3plus5’ has 8 MB. • Apple don’t tell that iPhone7 has 2 GB & 7Plus has 3 MB.• Is more RAM better? Not necessarily!• More RAM uses more power from battery.• This is regardless of what is in the RAM.• Closing apps to clear up available RAM also not good.• Because reloading the apps takes more energy.

System memory

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Analogue Representations of Info• Up to 1960, radio, TV, telephones & sound-recorders

used variable electrical voltages to represent information.• There were sort of digital systems, e.g. Morse code.• Only option for text was the printing press & paper copying.• In telephony, your voice produces variation in air pressure • A microphone converts this to a variation in voltage.• This is an analogue representation of voice.• This voltage variation is transmitted by wires or radio.• It may have to be amplified & filtered.• Many homes still have analogue telephones lines.• Early mobile phones were analogue & most radios still are.

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Analogue equipment

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Digital representation• Analogue voltage is sampled to produce binary numbers.• Easily stored or transmitted by wires or radio.• And converted back to analogue when needed.• Works for telephones, TV, radio, pictures, etc.• Data & text even easier to convert to numbers.• So now everything is reduced to binary numbers.• 110101011010001101001101 ….

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MooreMoore’’s Laws Law

Transistors per Intel chip

0.001

0.01

0.1

1

10

100

1970 1975 1980 1985 1990 1995 2000

Year

Mill

ions

of t

rans

isto

rs p

er c

hip

8008

8080

8086

286386

486Pentium

4004

Pentium II

Pentium IIIPentium 4

Number of transistors per square cm in state-of-art I/Cs doubles every 2 years

Is this a linear relationship? No!

In 2016, commercial proc with max number of trans is 24-core Xeon-HaswellEX with >5.7 billion.


Cost of a TransistorCost of a Transistor

0.000000001

0.000001

0.001

1

1000

1950 1960 1970 1980 1990 2000 2010 2020

Year

US

dolla

rs


Baby (1948)Baby (1948)


DRACO (2000)DRACO (2000)


50 years of progress50 years of progress

•• Baby:Baby:– filled a medium-sized room– used 3.5 kW of electrical power– executed 700 instructions per

second

•• DRACO:DRACO:– fills 7mm x 7mm of silicon– uses 215 mW of electrical power– executes 100,000,000

instructions per second


Energy efficiencyEnergy efficiency

• Baby : 3.5k / 700 = 5 joules per instruction• DRACO: 0.215 / 108 210-9 joules per instruction

>>2,000,000,0002,000,000,000 times more energy efficient than Baby• Assuming we got 5 miles per litre of petrol in 1948,

& achieved a similar reduction in energy efficiency in cars.• We would now get 1 million miles for a spoonful of petrol.

(Smartphone battery holds 5 Watt-hours = 18,000 joules)

James Prescott Jouleborn Salford, 1818

Joule: unit of energy (=1 newton-meter)As weight of an apple 1 newton, this is amount of energy required to raise an apple by 1 metre.Watt: unit of power (joule per second)


Memorable quotesMemorable quotes• “…computers of the future may have only 1,000 vacuum tubes and

perhaps weigh 1.5 tons.” - Popular Mechanics, Mar 1949

• “But what is .. (the microchip) ... good for?”- IBM engineer, 1968

• “There is no reason anyone would want a computer in their home”- Ken Olson, president/founder of DEC, 1977

• “640K [of RAM] ought to be enough for anybody”- Bill Gates, 1981

• “Speech bit-rate compression will never have applications in commercial telephony” – Anon, 1975

• "phone is not just a communication tool but a way of life“ Steve Jobs, ‘07.

• “A smartphone is a mobile games console that you can also make phone calls on” Andrew Leeming, 2014


SummarySummary

• Smartphones have evolved because of:– Moore’s Law allowing low cost, low power, low

weight– mobile operating systems & apps– digital media processing & compression

• for speech, music, image & video– digital communications, error correction, etc.– improvements in batteries (slow) & their usage


1. If Electricity costs 15p per KWh how much does it cost:(a) to charge your mobile phone? (< 0.1 p)(b) to run your old (200 W) desk-top for 1 day? (75p)(c) to use your (60 W) lap-top for 1 day? (<< 20p)(d) to use a 1 kW heater for 1 day? (£3:60)(e) to leave a 10 W (60 W equiv) light on all day? (<4p)

2. How many apples could your mobile phone battery raise by 1 meter? (18,000 !!)

3. If one mobile phone charge lasts all day, how much power does is it using on average? (0.2 W)

4. The 32-bit ARM processor in current mobile phones uses 0.4 mWof electrical power to execute 200million instructns per second. How much more energy efficient is it than (a) Baby & (b) DRACO?

Some questions

( (a) 25 billion (b) 12.5)


5. This is Steve Furber’s 1 million Arm core computr for simulating 1% of human brain. How long before we have such power in a mobile phone?

Some more questions

6. How much power may be used by all desktop computers in CS School & its cost per day. (200 kW, 5000 kWh, £750)

Power 0.06 W per Arm9 core


6. Manufacturers of smartphone batteries quote capacity in mAH (milli-Ampere-hours). Expressed in joules, what is capacity of a 2000 mAhbattery of voltage 3.7 Volts?(Answer: Capacity = 2000 * 3.7 = 7400 mwatt-hours = 7.4 watt-hours

Since 1 watt-second = 1 joule, 1 watt-hour = 3600 joules capacity = 7.4 * 3600 joules = 26640 joules)

7. In theory, for how long could you power a 1 kwatt heater from a mobile phone battery? (Answer: 18 seconds)

8. Why must a smartphone use DRAM or SRAM to run apps. What would happen if flash memory were used instead? (Slow, & if would soon fail)

9. On a PC, you can use a USB flash drive to supplement RAM. What may happen if you do this? (It was slow & lasted for a couple of days)

10.Why must both energy & power consumption be limited forsmartphones? Ans: energy consumptn for battery life & power consumptn limited to avoid destruction of components due to overheating

11.How many transistors were there in ‘the Baby’ (None)

Other Questions

mobile communicationsbarry/mydocs/mycomp61242/mc19_lectures/... · 2019-03-26 · lecture 5: 26 mar...

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