Full Mobile Number Portability TRAI

Chapter II: Full Mobile Number Portability
2.1 Presently mobile subscribers are availing the facility of MNP for
porting their mobile number within the same LSA. For example, if a
subscriber belongs to Andhra Pradesh LSA, he can port his mobile
number to any TSP of his choice within Andhra Pradesh LSA only.
Accordingly, in the present framework, MNP porting request is
processed amongst Recipient Operator, Donor Operator and the
MNPSP of the same LSA. Whenever a subscriber changes his LSA,
he needs to acquire a new mobile number of that LSA, otherwise he
will be under roaming, inviting higher call charges than a normal
subscriber.
2.2 The facility of pan-India portability will allow a subscriber to change
his LSA without change of mobile number. This means that a
subscriber of Andhra Pradesh LSA can port his number to any LSA
say Karnataka, Maharashtra, Haryana etc. Implementation of Full
Mobile Number Portability would therefore mean acceptance of a
porting request by the Recipient Operator from a mobile number
belonging to any of the LSAs of the country, irrespective of the fact
that the LSA from where the subscriber is porting his mobile
number and the LSA to which he wants to port his number belong
to the same or different MNP zones.
2.3 There will be regulatory and technical challenges in facilitating such
porting across LSAs. Some of the major challenges which need to
be deliberated are –
(i) how the request of the subscriber for porting will be
processed by the Donor Operator, Recipient Operator and
MNPSPs,
(ii) what changes are required in Number Portability Gateway
(NPG) of the operator and operator’s IT systems etc.; and 5
(iii) how much time will be required to complete the
modifications in the existing systems of the operators.
These challenges are discussed in the succeeding paras.
2.4 In the present framework on receipt of porting request, the
Recipient Operator forwards the same to the MNPSP of its MNP
zone. However, in full MNP scenario, the recipient operator will have
the following options which were described in the pre-consultation
paper dated 20th February, 2013.
Approach-1 : Recipient Operator forwards the porting request
to the MNPSP of its zone.
Approach-2 : Recipient Operator forwards the porting request
to the MNPSP of the other zone to which the Donor Operator
belongs.
Approach-3 : Recipient Operator forwards the porting request
to the MNPSP of the zone to which original number range holder
(the TSP to which the number originally belonged before its first
porting) belongs.
2.5 Stakeholders’ comments were sought on the most suitable approach
for implementation of Full MNP. The stakeholders were divided in
their opinion. While the TSPs supported Approach-1, the MNPSPs
supported Approach-3. None of the stakeholders supported
Approach-2. As there were differences in opinion between TSPs and
MNPSPs, meetings were held with the industry representatives viz.
COAI, AUSPI and MNPSPs. During the discussions, it emerged that
another approach, hereinafter called ‘modified Approach-1’, which
is a combination of Approach-1 and Approach-3, should also be
considered. These three possible approaches are discussed below:6
A. Approach 1: Recipient Operator forwards the porting request
to the MNPSP of its zone
2.6 In this approach, the Recipient Operator submits the porting
request to the MNPSP of its MNP zone. For example, if a subscriber
of Karnataka LSA wants to port his number from Karnataka to
Delhi LSA, he will submit his porting request to the Recipient
Operator of Delhi LSA, who in turn will forward the porting request
to MNPSP of MNP Zone-1. (which serves Delhi LSA) for porting.
2.7 On receipt of the porting request, the MNPSP of MNP Zone-1 will
verify the porting history of the mobile number by querying with the
MNPSP of MNP Zone-II(which serves Karnataka LSA). The query is
primarily to check whether the porting request meets the following
conditions:
(a) Completion of 90 days in its current operator’s network;
(b) No simultaneous porting is under process for the said
mobile number, in the other MNP zone.
If the porting request meets the above two conditions, the MNPSP of
MNP Zone-I will seek clearance from the Donor Operator of Karnataka
LSA. Further processing of porting request will take place as per the
existing porting process.
2.8 From the TSP’s perspective, this approach requires minimal
changes in the TSP’s Number Portability Gateway (NPG) as the
Recipient Operator continues to forward the porting requests from
the subscribers desirous of porting out their numbers to the MNPSP
of its zone. However, this approach has the following implications:
i. It will add complexity to the MNPSPs’ system as it requires
connectivity between the two MNPSPs.
ii. It will require synchronization of the database of the two
MNPSPs for ported numbers, porting history, database tables
etc. During discussions, MNPSPs stated that since they used
proprietary software, synchronization between the two MNP
systems has never been done earlier and would require 7
extensive development efforts and such a design will be
susceptible to errors in a live scenario.
iii. The MNPSPs also stated that new software development work
would be required for:
(a) developing mutually agreed interface specification by both
MNPSPs for requesting and obtaining the required data;
(b) modification to the current process, including new
messages, timers, error codes and reports;
(c) changes in the database design to maintain the data
received from other MNPSP;
iv. Real time port-in-progress validation and sharing of broadcast
information between the MNPSPs will increases dependency
between the two MNP Clearing House (MCH) systems. This will
increase system complexity, storage needs and will affect the
system performance (in terms of time and processing).
v. Testing in the above approach would be time and resource
consuming and also very costly.
B. Modified Approach 1: Recipient Operator forwards the porting
request to the MNPSP of its zone and the Donor Operator is
responsible to check the condition of 90 days and simultaneous
port requests
2.9 In the modified version of Approach-1, the need for connectivity
between the two MNPSPs has been eliminated. In this approach, the
Donor Operator will be responsible for verifying whether the
subscriber fulfils the eligibility condition of 90 days in the existing
network and also if the subscriber has made any simultaneous
porting request for the same mobile number. As such the
responsibility to check the above mentioned two conditions by
querying with the MNPSP of the other zone (Approach 1) will move
to the Donor Operator. The Donor Operator will be required to build
this check in their Number Portability Gateway (NPG). This will
require software changes in all the TSP’s NPG. However, the
advantage of this method is that there will be comparatively fewer8
changes requirement in the MNPSP’s systems due to the elimination
of connectivity between the two MCHs.
C. Approach 3: Recipient Operator forwards the porting request to
the MNPSP of the zone to which number range holder of the
number belongs.
2.10 In this approach, the Recipient Operator submits the porting
request to the MNPSP in whose zone the Number Range network
belongs. As all TSPs already have connectivity with both the
MNPSPs they will not have to make any changes in communicating
with the MNPSP of the other zone. This approach also does not
require interaction between the two MNPSPs. Therefore, this
method eliminates the need for connectivity /synchronization
between the two MNPSPs. However, in this approach, intelligence
needs to be built-into the operator’s NPG so as to forward the
porting request to the concerned MNPSP based on the identity of
the number range holder network.
2.11 In this approach the control on porting the mobile number will
continue to be with one of the MCHs. Even after a subscriber moves
to other MNP zone, all his subsequent porting requests (whether for
intra-Circle porting or Inter-Circle porting) will continue to be
processed by the MNPSP where his number originally belong. For
example, if a subscriber port his number from Delhi (which is in
MNP Zone-I) to Bengaluru (which is in MNP Zone-II), he will
approach the Recipient Operator of Karnataka LSA for processing
his porting request. The Recipient Operator will process the porting
request through MNPSP of Zone-I. Subsequently, if the subscriber
ports his number within the Karnataka LSA then also, the Recipient
Operator to whom the subscriber approaches in Karnataka LSA will
process the porting request through MNPSP of Zone-I only.9
2.12 All three approaches described above have their pros and cons.
Therefore, before deciding the approach to be implemented for full
MNP, the Authority decided to form a Focus Group consisting of
representatives from MNPSPs and TSPs to give their views on :
a. the preferred approach for implementation of full MNP;
b. changes required in the existing MNP system;
c. cost and time involved in various methods;
d. any other optimal feasible solution for implementation of
full MNP.
2.13 The deliberations of the Focus Group was coordinated and
facilitated by TRAI. After deliberating on all the possible
approaches, the Focus Group has unanimously recommended
Approach-3 for implementation of Full MNP in the country. (Report
at Annexure-II)
2.14 According to the Focus Group, cost requirement in Approach-3 will
be the least for both the MNPSPs. For TSPs, there will not be a
significant difference in the cost to be incurred in any of the three
approaches.
2.15 The Focus Group was also of the view that, irrespective of the
method adopted, TSPs will be required to upgrade their existing
backend systems such as CRM, mediation platforms, provisioning
systems / activation systems, billing systems, number
managements systems, recharging platforms, VAS management
systems etc, to support complete numbering plan and enable interLSA porting. Similarly, MNPSPs will also need to upgrade their MCH
to support complete numbering plan and enable inter-LSA porting
apart from enhancing billing system, Graphical User Interface (GUI)
etc.
2.16 The pros and cons deliberated by the Focus Group have been
examined by the Authority. The Authority agrees with the Focus
Group’s observation that the variation in the costs to be incurred in the three approaches will not be significant for the TSPs, whereas a
significant expenditure will be required for MNPSPs if Approach-1 is
adopted for implementation of full MNP. Further, the
implementation time for Approach-3 will be much less as compared
to Approach-1 or modified Approach-1. In addition,
2.17 Therefore, in the opinion of the Authority, Approach-3 will be the
most suitable approach for implementation of full MNP. Though the
Focus Group has not clearly mentioned the time frame for
implementation of the solution, the Authority is of the opinion that
6 months will be sufficient for operators to carry out the required
changes in their existing systems, complete inter-operator testing
and implement the solution.
2.18 Accordingly, the Authority recommends that Approach-3, as
described in para 2.10, should be adopted for implementation
of Full Mobile Number Portability. The TSPs may be given 6
months time to implement full MNP in the country.
Changes required in the MNP licence conditions:
2.19 For implementation of full Mobile Number Portability, following
licence conditions of MNP licence will require
modification/amendment:
(a). Scope of Licence:
In the scope of MNP license, the following condition will require
modification:
“12.5 The MCH and NPDB established by the licensee shall be
used by all telecommunication service providers (both existing &
new) (i.e. Basic, CMTS, UAS, NLD and ILD Licensee(s)) of the
licensed MNP zone for the purpose of supporting porting of mobile
numbers between mobile operators.”11
If full MNP is implemented with Approach-3, TSPs will have to
use the services of both the MNPSPs for processing the porting
request. Therefore, the restriction ‘the licensed MNP zone” in
clause 12.5 needs to be removed.
(b). Delivery of service:
The ‘Delivery of Service’ condition in clause 18.1 of the MNPSP
licence would require amendment -
“18.1 MNP is to be implemented in each intra Licensed Service
Area (LSA)……….”
In order to provide inter service area MNP service, the word
‘each intra’ may be modified to read as ‘inter and intra’
(c). Changes required in the DoT instructions dated 06th May
2009
DoT instructions dated 6th May 2009 regarding provisioning of
MNP will also require modification. Para 3(i) of the said
instructions is given below:
“ ….MNP is to be implemented in each intra license Service Area
(LSA) as per the schedule notified by the Licensor from time to
time…….”
The word ‘each intra’ in the para may be modified to read as
‘inter and intra’.
2.20 In view of the above, the Authority recommends that the DoT
should carry out the necessary changes as mentioned in the
above paras in the:
(i) existing MNP license; and
(ii) instructions of the DoT dated 6th May 2009, for
implementation of Full MNP.12
Upon acceptance of these recommendations, the Authority will carry
out necessary changes in the MNP regulations
Identification of inter-service area (STD) calls after implementation
of Full MNP
2.21 Presently, a calling subscriber can store the mobile number of the
called subscriber in one of the following possible ways in the
contact list of his mobile phone handset:
(a) Storing directly the mobile number of the called subscriber ;
(b) Storing the mobile number with prefix ’0’ ;
(c) Storing the mobile number with prefix ‘+91’ ,
2.22 In the Full MNP scenario, if a called number happens to be a ported
number that has been ported to a different LSA, a subscriber calling
that mobile number in the case of (a) above, will not be successful
as the called number has been ported out of the LSA and the caller
has to prefix ‘0’ to this called number – being an inter-service area
call. Therefore, by default, the calling subscriber will get ‘number
does not exist’ announcement. In the case of (b) and (c) above,
when a subscriber makes a call, though the call will be successful,
it will attract applicable STD charges instead of local charges (before
porting). There is a possibility that the calling subscriber may not
be aware that the number has been ported out to another LSA.
This may result in a subscriber complaining of higher charges.
2.23 This issue was raised in the pre-consultation paper and inputs
were sought from stakeholders on the need to inform the calling
subscriber through announcement prior to connecting the call. In
response, some TSPs suggested that identification of inter-service
area ported numbers and playing an announcement thereof, will
burden their network resources and will increase call set up time.
It was suggested that the subscribers may be made aware
of/educated to dial numbers in the +91 format which is the
standard dialing format, after Full MNP is implemented.



2.24 On the issue of higher call charges and possible subscriber
complaints, most TSPs were of the view that STD rates have
plummeted to almost the same level as local call rates; hence, it is
not a major issue. Further, in most cases, the calling party may
already be aware that the called party has moved to another LSA.
Therefore, the onus should lie on the calling party to bear the STD
charges, if applicable. One of the suggestions was to have a website
so that a query for a given telephone number can be given which
will provide information about the current serving operator/LSA for
the called number. This facility can be developed by the MNPSPs.
The Authority agrees with the above comments of the TSP and is of
the opinion that no action is required on this issue
UPC generation in J & K LSA in Full MNP Scenario:
2.25 As per the existing MNP process, a subscriber is required to
generate a UPC before submitting a porting request to the Recipient
Operator. In the Full MNP scenario, the location of the Recipient
Operator being in a different LSA, the Donor Operator will have to
ensure generation of UPC for subscribers under roaming. During
the pre-consultation, TSPs informed that UPC can be
requested/generated from any LSA (except in Jammu & Kashmir
LSA where roaming of pre-paid subscribers is not permitted).
2.26 In the J&K LSA, post-paid subscribers can generate a UPC as in
any other part of the country. However, pre-paid subscribers of
J&K can generate a UPC only by making a call to ‘1900’ instead of
sending an SMS. Therefore, in a full MNP scenario, the issue of
generation of a UPC while in another LSA may arise for pre-paid
subscribers of J&K as such subscribers are not permitted roaming.
2.27 The solution to this problem is that the subscriber of J&K LSA who
wants to port his number to any other LSA can generate the UPC in
J&K LSA and then apply for porting to any desired LSA.
Alternatively, he can convert his subscription from pre-paid to 14
post-paid which will enable him to generate a UPC under roaming,
and then request porting in any LSA.
Testing Fees for Acceptance Testing
2.28 During the consultation process, the TSPs and MNPSPs have stated
that apart from network implementation costs, significant testing
costs would be incurred by them.
2.29 The TSPs have requested to waive the testing fee by the DoT for
acceptance tests to be conducted for implementation of Full MNP.
2.30 On 24th November 2011, the DoT specified the Acceptance Testing
fee to be charged for various types of networks as follows:-
S.
No.
Fee to be charged from
TSP/ ILDOs/ MNPOs
Unit Price (per network/ per LSA.
Per gate way, per site)
1 UASL /CMTS Service
Provider
Rs. 307228 (per network per LSA)
2 Basic/ WLL Service
Provider
Rs.189360 (per network per LSA)
3 International Long Distance
Operator (ILDO)
Rs.189360 (per Gateway)
4 MNPO Rs.279800 per site (Production/
Disaster)
Rs.60360 per network per LSA
(GSM/ CDMA)
2.31 Before the launch of MNP, DoT had already conducted acceptance
test through respective TERM cells of DoT for which testing fee had
already been charged as per the above said circular. Now, Full MNP
is being mandated pursuant to NTP-2012 and testing is to be
carried out for various scenarios due to a change in the process.
Therefore, the Authority recommends that the DOT may
consider the request of the operators and reduce the
Acceptance Testing Fee to 25% of the Current Fee.15



Chapter III: Summary of recommendations
3.1 The Authority recommends that Approach-3, described in the
relevant para (2.10), should be adopted for implementation of
Full Mobile Number Portability. The TSPs may be given 6
months time to implement full MNP in the country. ( ¶2.18)
3.2 The DoT may carry out the necessary changes in the:
(i) existing MNP license; and
(ii)instructions of the DoT dated 6th May 2009, for
implementation of Full MNP. (¶2.20)
3.3 The DoT may consider the request of the operators and reduce
Acceptance Testing Fee to 25% of the Current Fee. (¶2.31)

Cellular Phone Technologies Comparision

Encoding and Multiplexing
Overview
With thousands of cellular phone calls going on at any given time within a city, it certainly would not work for everyone to talk on the came channel at once (as in CB and short-wave radios). Therefore, several different techniques were developed by cell phone manufacturers to split up the available bandwidth into many channels each capable of supporting one conversation. The following sections will discuss each technology and how it works.
Analog vs. Digital
While the distinction between analog and digital encoding is probably obvious to most readers, a short discussion is included for those who are not. Essentially, analog broadcasts audio as a series of continuously changing, voltage levels representing the amplitude of the voice conversation. When sent on the cell phone network using the standard frequency modulation (meaning voltage levels translate into frequency shifts) into channels separated by 30 kHz, we find that the amplitude can be effectively transmitted at 15 kHz due to Nyquist limitations.
Instead of sending data as various voltage levels, a digital signal quantizes the voltage levels into a number of bins (typically 28 or 256 representing an 8-bit encoding). These bins are encoded as a binary number and sent as a series of ones and zeros. This allows for digital compression in the encoding stage enabling voice to be sent at as little as 8000 bits per second.
FDMA
FDMA stands for "frequency division multiple access" and, though it could be used for digital systems, is exclusively used on all analog cellular systems. Essentially, FDMA splits the allocated spectrum into many channels. In current analog cell systems, each channel is 30 kHz. When a FDMA cell phone establishes a call, it reserves the frequency channel for the entire duration of the call. The voice data is modulated into this channel’s frequency band (using frequency modulation) and sent over the airwaves. At the receiver, the information is recovered using a band-pass filter. The phone uses a common digital control channel to acquire channels.
FDMA systems are the least efficient cellular system since each analog channel can only be used by one user at a time. Not only are these channels larger than necessary given modern digital voice compression, but they are also wasted whenever there is silence during the cell phone conversation. Analog signals are also especially susceptible to noise – and there is no way to filter it out. Given the nature of the signal, analog cell phones must use higher power (between 1 and 3 watts) to get acceptable call quality. Given these shortcomings, it is easy to see why FDMA is being replaced by newer digital techniques.
TDMA
TDMA stands for "time division multiple access." TDMA builds on FDMA by dividing conversations by frequency and time. Since digital compression allows voice to be sent at well under 10 kilobits per second (equivalent to 10 kHz), TDMA fits three digital conversations into a FDMA channel (which is 30 kHz). By sampling a person’s voice for, say 30 milliseconds, then transmitting it in 10 milliseconds; the system is able to offer 3 timeslots per channel in a round-robin fashion. This technique allows compatibility with FDMA while enabling digital services and easily boosting system capacity by three times.
While TDMA is a good digital system, it is still somewhat inefficient since it has no flexibility for varying digital data rates (high quality voice, low quality voice, pager traffic) and has no accommodations for silence in a telephone conversation. In other words, once a call is initiated, the channel/timeslot pair belongs to the phone for the duration of the call. TDMA also requires strict signaling and timeslot synchronization. A digital control channel provides synchronization functionality as well as adding voice mail and message notification. Due to the digital signal, TDMA phones need only broadcast at 600 miliwatts.
CDMA
CDMA stands for "code division multiple access" and is both the most interesting and the hardest to implement multiplexing method. CDMA has been likened to a party: When everyone talks at once, no one can be understood, however, if everyone speaks a different language, then they can be understood. CDMA systems have no channels, but instead encodes each call as a coded sequence across the entire frequency spectrum. Each conversation is modulated, in the digital domain, with a unique code (called a pseudo-noise code) that makes it distinguishable from the other calls in the frequency spectrum. Using a correlation calculation and the code the call was encoded with, the digital audio signal can be extracted from the other signals being broadcast by other phones on the network. From the perspective of one call, upon extracting the signal, everything else appears to be low-level noise. As long as there is sufficient separation between the codes (said to be mutually orthogonal), the noise level will be low enough to recover the digital signal. Each signal is not, in fact, spread across the whole spectrum (12.5 MHz for traditional cellular or 60 MHz in PCS cellular), but is spread across 1.25 MHz "pass-bands."
CDMA systems are the latest technology on the market and are already eclipsing TDMA in terms of cost and call quality. Since CDMA offers far greater capacity and variable data rates depending on the audio activity, many more users can be fit into a given frequency spectrum and higher audio quality can be provide. The current CDMA systems boast at least three times the capacity of TDMA and GSM systems. The fact that CDMA shares frequencies with neighboring cell towers allows for easier installation of extra capacity, since extra capacity can be achieved by simply adding extra cell sites and shrinking power levels of nearby sites. CDMA technology also allows lower cell phone power levels (200 miliwatts) since the modulation techniques expect to deal with noise and are well suited to weaker signals. The downside to CDMA is the complexity of deciphering and extracting the received signals, especially if there are multiple signal paths (reflections) between the phone and the cell tower (called multipath interference). As a result, CDMA phones are twice as expensive as TDMA phones and CDMA cell site equipment is 3-4 times the price of TDMA equivalents.
GSM
GSM stands for "Global System for Mobile Communications." GSM is mostly a European system and is largely unused in the US. GSM is interesting in that it uses a modified and far more efficient version of TDMA. GSM keeps the idea of timeslots and frequency channels, but corrects several major shortcomings. Since the GSM timeslots are smaller than TDMA, they hold less data but allow for data rates starting at 300 bits per second. Thus, a call can use as many timeslots as necessary up to a limit of 13 kilobits per second. When a call is inactive (silence) or may be compressed more, fewer timeslots are used. To facilitate filling in gaps left by unused timeslots, calls do "frequency hopping" in GSM. This means that calls will jump between channels and timeslots to maximize the system’s usage. A control channel is used to communicate the frequency hopping and other information between the cell tower and the phone. To compare with the other systems, it should be noted that GSM requires 1 Watt of output power from the phone.
Call Handoff
It is apparent that cells must somehow overlap, and when a user travels between cells, one cell must hand the call off to the other cell. The cells must also not interfere with each other. This is accomplished by giving each cell a slightly different chunk of the frequency spectrum (note that CDMA does not do this) and by measuring power levels. When the power level of the user begins to fade, the cell tower determines which cell is the closest cell. Upon finding this information, the current cell tower sends an over-the-air message to the new cell tower and to the cell phone. At this point, the new cell tower picks up the call and the old one drops the call as the cell phone switches frequencies. This type of handoff is called a "hard handoff" since the audio feed is lost for between 10 milliseconds and 100 milliseconds while the new tower picks up the signal. Often these "hard" handoffs fail when the new tower tries to pick the call up, leading to frequent dropped calls.
In most systems, each cell tower typically receives a 1.8 MHz frequency spectrum. In normal cellular systems that have a 12.5 MHz spectrum (not the high-band PCS systems that have more bandwidth), this allows for 7 cells before cells have to reuse frequencies. Generally, there are 1-2 cells and 10-20 miles separating cells using the same frequency in order to minimize interference.
Security
One of the largest problems in wireless communication is security. There are two worries: Other people listening into phone calls and other people illegally billing time to a user’s account (called "phone cloning").
Unfortunately, analog phones transmit in plain FM, and provide no security. For instance, a few years ago, Newt Gingrich had a cell phone conversation taped by someone using a simple police scanner, which is designed to receive police activity on the CB frequencies. Since analog phones have such weak security, the architects of digital technology designed digital phones with much more robust security.
Digital phones employ encryption to secure the phone and the conversation. Encryption is used in TDMA and CDMA to make sure that it is almost impossible to "latch" onto a conversation. The encryption works by picking a key that is used in an equation that compresses the audio. The encrypted key is sent to the cell tower so the cell tower knows how to decode the conversation. Therefore, even if the person with the scanner finds the channel and time slice you are using, they would need to find the encryption code to make sense of the signal. It is also important to mention that CDMA also uses its modulation code to provide increased security, resulting in over four billion possible encryption codes. Cell phones also must be protected from cloning. By encrypting the cell phone number and related information when sending the information to the switch, cloning is prevented.
Source:
How Cellular Phone Technologies Compare Best of the Net Very good and concise explanation of how cell phone networks work and what are the differences between CDMA, TDMA, FDMA and GSM.

Smart Antennas Facilitate 4G

Vendors already are dabbling in 4G smart antennas. Bell Labs' technology — called Bell Labs Layered Space-Time (BLAST) — is being studied as part of one EU-sponsored pre-competitive advanced antenna-technology project. A BLAST prototype uses an array of eight transmit and 12 receive antennas. During its first weeks of operation, it achieved at least 10 times the wireless capacities of today's fixed-wireless-loop systems.
“The idea here is if you try to increase capacity of a wireless system, you run up against a brick wall because capacity is limited by the interference of other users, so increasing bit rate by increasing power does not work at all,” Valenzuela said.
Although the classic approach is to throw more bandwidth at the problem, high prices and low spectrum availability have made this option unattractive. However, several years ago, the idea was introduced that adding transmit and receive antennas can create parallel channels that don't interfere with one other. This process does not require increased power or additional frequency.
“MIMO antennas are a very practical system, and if you combine it with adaptive coding and modulation, interference cancellation and beam-forming technologies, you can realize gains that are 30 times better, in terms of bit rates and capacity, than 3G,” Nortel's Javed agreed.
Nortel has operational MIMO systems in its lab. Tests show a 10X capacity increase at speeds of 20Mb/s. Next year, the company expects to hit 40Mb/s, as well as conduct field trials of its technologies.

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