MOBILE AND COMPUTER COMMUNICATIONS THROUGH

COLOUR SIGNALS – AN APPROACH NOTE

Rajarshi Sanyal

Reliance Infocomm, Mumba, India

Keywords: Colour Circle, Video BTS / BSC, RGB Encoder , RGB Decoder.

Abstract: The objective of this paper is to discuss a methodology for achieving mobility through colour signals

applicable for wireless networks. The colour is used as the address of the wireless nodes in the network and

for carrying the signaling and the bearer traffic. The present day video systems that can generate millions of

colours, in its electronic form have been utilized for setting up a wireless network, serving mobile stations

or computers as its nodes. A specific colour level is assigned for a user as its address and for exchange of

data. Theoretically, the number of users that can be served by such colour circle has no upper cap, because

the possible colour combinations are virtually infinite. But it is constrained by the sampling frequency of the

available video technologies. The paper provides a basic introduction of the technology and attempts to

compare with the prevalent wireless technologies on various aspects. The technology finds application for

Wireless Computer Networks, Closed User Networks and for Mobile Networks.

1 INTRODUCTION: THE

COLOUR CIRCLE AND

WIRELESS NODES

Isaac Newton said, “Indeed rays, properly expressed,

are not coloured.”

Spectral power distributions (SPDs) exist in the

physical world, but colour exists only in the eye and

the brain. Colour is the perceptual result of light

having wavelength from 400 to 700 nm that is

incident upon the retina. The question is, whether

the colour, generated by the electronic video systems

and perceived by the human retina can be utilized to

render individual / discrete identities to millions of

network nodes which can eventually form a mobile

or computer network.

The nodes of the wireless network for mobile or

computer are represented as specific colour levels in

the colour circle. A band of saturation level is spread

across the colour vector, a sub-band of which is

meant for signaling and the remaining for bearer

traffic. For a mobile network, the coordinate of the

Mobile Station in the colour circle is decided during

provisioning. Similarly, for a computer network, the

IP address (and subnet mask), of the computer or

peripheral decides the position of the node in the

colour space domain. Hence for a mobile or

computer network, the MIN and the IP address

(subnet mask) needs to be a function of the phase of

the colour vector and the band of saturation level for

transcoding voice and signaling.

MIN (E.212 NP) / MDN (E.164 NP) = f (Ø , S

) for

mobile network.

IP (Class A, B and C) = f (Ø, S

) for computer

network,

Where S

=> the band of saturation level allotted to

the user for signaling and bearer data

Figure 1: Space coordinate representation of the Wireless

Nodes in the colour space domain.

Transcoded

Voice

Signaling

Data

Sanyal R. (2006).

MOBILE AND COMPUTER COMMUNICATIONS THROUGH COLOUR SIGNALS – AN APPROACH NOTE.

In Proceedings of the International Conference on Wireless Information Networks and Systems, pages 73-78

 SciTePress

2 DESIGN BASIS OF A

WIRELESS COMPUTER

NETWORK BASED ON

COLOUR SIGNALS

The basic architecture of a single MAC Colour

Computer network (wireless) provides mobility

within a large Location Area. However, it is also

possible to actuate mobility across multiple MAC

Networks.

Figure 2: Architecture for Wireless Computer Network.

Node A Initiates to set up a wireless connection with

Node B. It generates a colour train within the

saturation band allotted for signaling (Pat. No.

188052, Govt of India, October 1995).

The signaling data contains the IP Address (Sub net

mask information) of Node A and Node B. The

video repeater, which acts as an access point,

collects the information from various sources,

aggregates as a common Chroma Signal and

forwards it to the colour server. The colour server

receives the colour signals from all the sources (the

repeaters) and forms an aggregate chrominance

signal for the downlink which is broadcast in the

network area. The colour server (which is the heart

of the network and actuates all the virtual routing

functionalities), generates a colour train within the

saturation band allotted for the Node B. The Node B

acknowledges the connection request .The colour

server sets up a semi permanent connection between

Node A and B on the assigned Ø and S

for Node A

and Node B, respectively.

Using the HDTV 1080i technology , which has a

colour sampling frequency of 74.25 Mhz (each

colour sample corresponds to a bit) , and assuming

that each wireless node enjoys a forward and reverse

data rate of 2Mbps, the number of simultaneous

users that can be accommodated in a single colour

circle is 37. The deployment architecture can be the

same followed in WLAN where each colour circle

creates a Basic Service Set (BSS) and multiple BSSs

form an Extended Service Set. The Colour server

will essentially perform the functionality of a

Distribition System (DS) which actuates

intercommunication between multiple access points.

The power requirement in the handset to achieve an

uplink data rate of 2 Mbps depends on its distance

with the access point. However, the access points are

inexpensive dumb video repeaters which do not have

any discrete address in the network . Setting up a

colour hot spot will be cheaper and easier compared

to the existing wireless access technologies. Also the

number of the repeaters in the network area can be

increased to minimize the power requirement of the

wireless nodes.

2.1 Network Architecture of a

Standalone PCS Wireless

Network (Closed User Group

and not Linked to External

Legacy Networks)

Figure 3: Network Architecture of PCS network.

The mobile station consists of the chrominance

signal transmitter, which generates colour as a

function of the dialed E.164 number. In a closed user

environment with limited users, the numbering plan

will be fairly simple. Hence the algorithm for

generating the color as a function of the E.164

Number can be housed in the Mobile Stations.

Assuming that we use the HDTV 1080i technology ,

and the digital vocoder transcodes the voice at a

sampling frequency of 8 KHz , the number of users ,

that can communicate in a colour circle

simultaneously in a given network on a single

channel / carrier frequency = 74.25 x 10^3 / 8 =

9280 (HDTV 1080i specifications ). This however

does not take into account the interference factors ,

which will lessen the spectral efficiency to some

extent.

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2.1.1 Functional Specification of the Mobile

Station

The Mobile Station will be capable for setting up a

forward and reverse channel with the network for

voice and signaling. It consists of the following

functional blocks (Sanyal, Patent App.No.

0163/MUM/2006 , Govt. of India). The system

components for supporting the supplementary

services are not included.

• NAM & SIM Holder Interface – Number

Assignment module which stores all the

MS related parameters , like MIN/IMSI ,

MDN , Channel Frequency (UHF or VHF)

• Colour Generator and transmitter: Mainly

used for making an outgoing call and to

enable full duplex communication while in

a call.

o E.164 Number to Hue and

saturation level converter for

generation of the colour as a

function of the B Party Number

(Dialed Number)

o Video Encoder

o Phase shifter

o Video UHF/VHF Transmitter

• Colour Receiver

o Video Transreceiver

o Phase detector

• Logic module : to invoke and respond to

different signaling messages and

accordingly decide to make or break the

speech circuit.

• Audio Unit

o Audio PreAmp & AMP

o Audio to RGB transcoder and vice

versa

o AM Bandpass filter

• Keyboard encoder

• Display Unit : LCD display unit

• Power supply Unit

Figure 4: Block diagram of Keyboard encoder.

When a number is dialed, the subcarrier frequency

is passed through an amplitude modulator (to actuate

the saturation level) and is phase shifted (to form

the hue) by a phase shifter to synthesize the desired

C signal which is a function of the dialed number.

The amplitude and the phase are determined by a

logic unit (as shown in the diagram in Fig. 4) which

is interfaced to the keyboard generator (Patent

App.No. 0163/MUM/2006, Govt. of India, February

2006).

Figure 5: Keyboard Encoder for PCS Mobile Station.

MOBILE AND COMPUTER COMMUNICATIONS THROUGH COLOUR SIGNALS – AN APPROACH NOTE

2.2 Deployment Architecture for a

Mobile Network

Figure 6: Mobile Network on Colour Signals.

Each Color Circle pertains to a single Location area

and not subdivided into multiple orthogonal cells, as

is present in the existing technologies like GSM or

CDMA . The BTS is replaced by Video

Transreceivers (termed as V-BTS ) placed all over

the network coverage area which can establish an

uplink and downlink channel in UHF / VHF with the

handsets (Sanyal, Patent App. No. 0163/MUM/2006,

Govt. of India). The chrominance signal transmitted

from the V- BTS is primarily a broadcast signal

containing colour information , sampled at a

specific frequency ( for HDTV , the sampling

frequency if 74.25 Mhz) for all its users in a given

network coverage area. Each handset after receiving

the chrominance signal demodulates it and filters out

the colour signal (in terms of R – G – B Levels )

pertaining to the specific hue and the band of the

saturation level in digitized form. Within the specific

band of the saturation level allotted for the

subscriber , say Band A (ranges 10% to 35 % ) , a

specific sublevel say Band A1 carries the signaling

information (for paging , Alert with Info , etc) and

the Band A2 , carries the digitized voice

information. The heart of the network is a colour

server which processes all the colour information.

The colour server interoperates with the MS through

the V-BTS / V-BSC and exchanges the SS7

signaling information with the core network

accordingly. The speech circuit between the A and

the B party is established over the band of saturation

level tied up with the colour level that has been

assigned for both the parties.

The functional specification of the mobile station is

the same as that show for the CUG PCS network,

except for the fact that the Keyboard encoder does

not need to hold the algorithm which ports the dialed

E.164 number to color generator. This function

instead exists in the colour server .

The primary functions of the colour server are the

following.

1. Performs all the colour signal processing for the

access network

2. Formulates the colour train which is a function

of the dialed E.164 mobile number (of the same

serving market).

3. Performs the Signaling operations (on SS7) with

the core network

4. Interoperates with the V-BTS/V-BSC for the air

interface related operations.

5. Interfaces with the Legacy Networks (on

associated mode of signaling and PCM Voice

trunks on F Links and on A links on quasi

associated mode ).

6. Call Data Record generation for Mediation /

Billing

7. Call routing for the legacy network

8. SSP Functionality for Intelligent network

operations

9. Supports Supplementary Services

2.2.1 Advantages

¾ Eliminates the need of complex time and space

switching matrix present in modern days mobile

networks.

¾ No need of frequency re-use , needs lesser

number of channel frequencies compared to

GSM or CDMA.

¾ No need of complex planning of macro / micro /

pico cells. Coverage area can be split up into

broader areas and scattered with Video

Repeaters .

¾ Instead of increasing the number of cells to

increase coverage, as in GSM/CDMA , it is only

required to add more inexpensive video

repeaters to increase the size network area ,

until the maximum number of subscribers that

can be catered by a single color server is not

reached. Power Requirement of the Mobile

Station depends on the number of repeaters

placed in the coverage area. No power misuse

due to increased signaling, as in GSM or

CDMA.

¾ Signaling overhead is much less , resulting in a

cheaper network. No complex handoff

mechanisms required (like soft handoff or hard

handoffs) or other operations related to mobility

management.

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¾ Reduction in the backhaul / transport. The calls

within the same V-BTS can be processed

locally and need not be taken towards the colour

server .

¾ Faster deployment, low maintenance cost of the

network, less manpower required for operations.

¾ Can be built upon the existing television /cable

TV network . Satellite transponders meant for

video communication can also be used for voice

and data.

The following study shows a comparison of the

proposed technology for mobile networks and GSM

in terms of the network capacity and spectral

efficiency.

2.3 Capacity Calculation

In GSM, the radio spectrum in the bands 890-915

MHz for the uplink (mobile station to base station)

and 935-960 MHz for the downlink has been

reserved in Europe for mobile networks. The uplink

and downlink band , each of 25 Mhz , is divided in

124 channels. Each of the 124 channels can support

8 separate connections with one time-slot per

connection . Theoretical limit of 124 channels x 8

connections per channel = 992 connections per cell.

But, many frequencies in any particular cell are not

used to avoid conflicts with neighbors, resulting in

much reduced support of simultaneous calls.

Capacity in terms of Call Connections per Mhz of

Bandwidth in GSM = 992 / 25 = 40 or lesser.

Span of a cell in GSM = few Kilometers radius. Size

is constrained by technology.

The 1080i HDTV theoretically requires a 37 MHz

video bandwidth. Sample rate for 1080i HDTV is

74.25 Mhz. The subscriber’s speech will be

transcoded through the VOIP codec, which requires

a sampling frequency of 8khz (data taken for VOIP

Codec specification). Simultaneous calls supported

= 74.25Mhz / 8 KHz = 9280.

Capacity in terms of users per Mhz of Bandwidth =

9280 / 37 = 251.

Span of a cell = An entire coverage area can be

made up of a single cell, and size of the cell is not

constrained by technology , the determining factor

being the call attempts that is required to be

supported.

Figure 7: Call flow for a call initiated by the A party towards the B party is shown below (ANSI 41 – D Specification / ITU-

T MAP 2 Specification).

MOBILE AND COMPUTER COMMUNICATIONS THROUGH COLOUR SIGNALS – AN APPROACH NOTE

3 EXPERIMENTAL SETUP FOR

VOICE COMMUNICATION ON

COLOUR SIGNALS

The experiment was performed based on the primary

colours (Red , Green , Blue) .With the setup, three

VHF colour transmitters ,each capable of

transmitting red , green and blue colour levels

respectively were transmitting modulated Saturation

level (voice transcoded to colour with the aid of a

suitable driver) on these basic colour levels (RGB)

.The receiver decodes the three different voice

signals transmitted on the three basic colour levels

and feeds the signals to three different speaker

outputs. The audio output in each channel was

distinct with no distortion.

The phase and the voltage of the basic color signal

(RGB ) are determined by the following equations.

The equation of the illuminance signal (Y) is

Y = 0.30 R + 0.59 G + 0.11 B

Hence R-Y = 0.7R - 0.59G - 0.11B

R –Y is maximum when G and B are 0.

Similarly , B-Y = 0.89B – 0.59G – 0.3 R

B-Y is maximum when G and R are 0.

When there was no audio input , and hence no signal

pertaining to the Green and Blue section , and when

a constant voltage output of 1 volt was obtained

from Red color output (in the chroma section of the

video transmitter) , the Magnitude of the composite

chroma signal is |C| = √ (R-Y)

+ (B-Y)

= 0.7v

The phase angle of the color vector , in that situation

which governs the hue is

Φ = tan

-1

(R-Y) / (B-Y)

= - 66.80

REFERENCES

Sanyal, Rajarshi, 1995. A system of wireless networking

of computers in the UHF”, Patent

Document (Pat. No. 188052, Govt of India, October

1995)

Sanyal, Rajarshi, 2006.Framework for Realizing Mobile

Network Through Colour Signals. Patent App.No.

0163/MUM/2006, Govt. of India, February 2006).

ANSI 41 – D Specification / ITU-T MAP 2 Specification

HDTV 1080i Specification

Figure 8: Triple Audio Receiver and Transmitter on Basic

Colour Signals (RGB) as carrier signals and built upon

PAL VHF Transmitter and Receiver.

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