GoLang :Simulation of QPSK SER in AWGN Channel

The new (atleast to me) programming language Go. The philosophy behind the change and need for the new notations and the language writing itself impressed me. I am a long time C,C++ user. The website has few sample programs to run online itself (Check the Tour).

Wanted to test out a simple code within my domain. And what else could be simplest code for a wireless system modelling - A BER performance of QPSK modulated symbols in AWGN channel. Here goes the code.

Video of Simulator

Pico deployment in annular fashion 

A simple GUI for learning the SINR distribution when Pico base-stations are deployed in different ways by specifying in config file.

Mobile Network Cell-edge Simulation

Some time back, I had simulated the aspect of cell-edge scheduling in a wireless cellular network. The snapshot is embedded. I used Qt based library for the visualization and itpp library for the back-end to simulate the signal processing, schedulers, CDMA base-station, receivers.

The GUI uses a dynamic webkit to present Google Map, with labels and other locations. Above the Map layout, there are graphical elements in different colors. The centre of circle, with three sectors in each cell. The different shades (other than BLUE) represents the SINR of the UEs.  Due to the wrap-around model one may notice that a UE at one of the cell  is being scheduled with a base-station too far from that cell.

Modelling cellular system

In my previous post, I uploaded a snap shot of GUI version of my simulator. Am interested in developing a professional multi-cell deployment simulator tool with the following features. The targeted end-user client would be an cellular operator, vendor, network deployment study team or non-profit organization for generating whitepapers.

Deployment trends in cellular communication will take a new paradigm shift. Unlike the sectorized deployment of narrowband systems like GSM, the broadband systems like LTE, WiMAX will do frequence reuse deployment. The primary service on these networks are packet data service. The goal would be to provide any-time UP kind of data-pipe, similar to a dedicated broadband DSL connection. Whether the packet data is short time (like Social Network, Messenger updates, or Push POP notifications) or long session connections like watching streaming video (iptv, youtube, widevine ) or uploading live video ( justin TV, ustream). And a reliable connection on-the-go (Dont want a banking transaction query or link to break).  This requires to have sufficient coverage to provide a minimal reliable throughput link. 

Multicell simulation GUI Interface

Have been a long time wish, to make a completely configurable simulator for wireless system all phy layer tuning etc. I have been using itpp and g++ on linux for my simulator work see some description here (Personal blog). Later I added a frontend to manage the input configuration (screenshot  is here)

Now, recently I finished a tool/interface to display a multicell deployment scenario with macro, mobiles and pico/small cells. ( droping of base-stations and nodes, pathloss calculation was done by a friend). The screenshot is

The green dots are pico transmitters, Black are base-stations with directional antennas. Other nodes are receivers and the color shows the SIR of the node (Lowest : blue, Highest Orange). The front-end was developed using Qt library (Open source)

Small cell deployments in next generation wireless technology

In my opinion, this is going to drive the new deployment strategy. LTE is purely a data aimed technology. Compared to earlier wireless technology 3G,GSM, cdma2000 which primarily was focused on providing voice.

Think of voice, which consumed the a good and reliable amount of wireless resource (time (GSM slots) or codes (cdma/wcdma long codes)) for short duration of time. While when one is talking about packet services. One does not want to "dial-up" a data session. Its an always on connectivity when you are connected to through a 4G-MOBILE terminal. The "dongle" based access is a different case.

IPhone Rivals Dispute Apple's Antenna Claims | John Paczkowski | Digital Daily | AllThingsD

IPhone Rivals Dispute Apple's Antenna Claims | John Paczkowski | Digital Daily | AllThingsD

Old players of mobiles phones like nokia, samsung, blackberry have been enjoying their good share of market since iphone got released. Especially, touchphone only had meant "stylus" based touch. So there was no attempt in designing UI for mobile apps that were capable to handle "finger" touch. Apple demonstrated made it real with itouch.

Mukesh Amban's bet? Wireless boom redux - dnaindia.com

Mukesh Amban's bet? Wireless boom redux - dnaindia.com

Few comments on the technical flaw in the article

The first statement itself is technically incorrect!! "Wimax-LTE (Long Term Evolution, the fourth-generation mobile technology invented by Qualcomm Inc of the US"

Author of the article should consult some wireless technology person..

a) Wimax-LTE are two different technologies..

b) Qualcomm did not invent LTE!!

LTE is colloborative standard developed by the 3GPP (considered to be leaded by EUROPEAN countries)

c)LTE is based on OFDM not (CDMA for what Qualcomm is better known for)

d) OFDM has been more than 40-50 years and 802.11 is based on OFDM techniques

Wireless systems - Part I

Its is also posted here http://ssendilkumar.wordpress.com/ 
Introduction

The principle of wireless system design is to transfer information from source to destination without a physical (wired) medium. This is the primary goal. How efficiently can one do this is the design challenge, therein brings in different technology to approach. So how do we define the efficiency metrics ? The resource or the medium to transfer the data or information is the limited spectrum for a limited time. Given a limited Spectrum-time plane, are we allowed to transmit or use this resource at any spatial location? This factor governs the amount of power you are allowed to transmit with. This leads to define a metric in terms of information/Hz/s/watt.

A little bit more on Metric

Design of a “scheme” – A chain of post-processing stages applied on the information before transmitting as electrical waveforms and later into electro-magnetic waveform, has been a historical area of research for all wireless communication experts. Many classical work has been published to maximize efficience of a particular stage. For e.g, optimal M-ary QAM mapping of constellation, capacity bounds on performance on error-control-codes, optimal design of RF filters to reduce emission of energy out of the alloted band, design of antennas such that maximal energy transfer between electrical signal and EM waves is accomplished. Not all the stages are independent of the preceding and following stages. For e.g, packing more information bits into a complex constellation might not have constant envelop which might be stringent requirement on the linearity of the power-amplifier.

The optimal scheme is also a function of the operating point of the spectrum for e.g., one might achieve a “x”/Hz/s/Watt for a spectrum centered at 800MHz, while the same metric is different for spectrum centered at 2GHz. Second, the acheivable metric is also a function of the spatial distribution of stationary and non-stationary elements (like building, moving vehicles, rain, greenary) in the wireless medium. For e.g. in a urban city one might achieve a better “information transfer metric” compared to an open-air/land rural area. Hence, the optimal design is actually not optimal for all time, place and spectrum. This leads to any adaptive optimal designs which can tune the different “stages” for optimization. Ofcourse this needs a “feedback” mechanism to tune them. For example, when the received signal energy decreases due to a path-loss or shadowing loss – the receiver can request to increase the transmit power, reduce the constellation size, increase more error-correcting bits to decode the information, wait for conditions to improve and transmit a burst of information, retransmit information through alternate “path” to increase the detection probability. So one has many approaches to address or acheive a target “metric”. Sometimes (many times) some solutions have practical limitations due to the tx/rx implementation or the technique itself. For e.g, the steps at which power control is applied, fractional modulation size (e.g 3-PSK, 10-qam) are not conventional bit packing schemes. 

To be continued.. 

Understanding wireless systems

I will be starting a series of post on understanding wireless systems from my perspective. I assume no-minimal technical requirement on the reader other than reading english :).

I would be glad to read comments, queries and suggestions or mistakes in my techinical flow.

Looking for some help!!

I am looking for some B.E/Master's student who is interested in some C++ programing for simulating wireless systems. I have a good library of my own. I am tied of lot of work related to standardization stuff.
This is my first attempt to see how many approach me through this blog.