This document discusses how to increase 4G LTE network downlink capacity through a simple software patch called BOMA. BOMA can provide a 50-60% boost in downlink capacity through software updates to LTE base stations and devices, requiring no hardware changes. This increases capacity much faster and cheaper than alternatives like acquiring new spectrum that require billions in spending and 3-5 years for implementation. The document provides technical details on how BOMA pairs users with different modulations to improve spectral efficiency over traditional OFDMA.

1. How To Increase 4G LTE Network Downlink
Capacity With a Simple Software Patch –
BOMA
2016

2.  Global mobile data traffic will increase nearly eightfold [1] between 2015 and 2020.
 To meet this exponential growth in data demand, Mobile Operators can take
different approaches to boost network capacity as shown below.
2015 2020
Mobile
Data
Traffic
8x growth [1]
Use new Spectrum Densification
Macro
Macro
+
Pico
Increase Spectral Efficiency
Massive MIMO
Full Duplex
Communication
[1] http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networking-index-vni/mobile-white-paper-c11-520862.pdf

3. Network
Optimization
Site Acquisition
+
Backhaul
challenges
Chipset &
Network
Hardware
Development
Small Coverage
Capacity Low Frequency Band
Coverage
High Frequency
Band
Limited deployment use cases such
as indoor or point –to-point links
2016 2017 2018 2019 2020
Standardization
& Channel
Models Study
Massive # of Sites
Development due
to small coverage
Commercial
Launch
Massive # of Sites
Development due
to small coverage
Commercial
Launch
Multi-year Standardization Activity
Chipset & Network
Hardware
Development
Network
Testing
Commercial
Launch
• Current strategies require either massive CAPEX and/or at least several years of
standardization and feature development.
• Mobile networks need a simple cost effective solution that can boost capacity TODAY!

4. 25% DL Capacity
Boost
PROS ~25% boost in downlink LTE Capacity.
CONS
$18.2B CAPEX spending on spectrum. Network development will be additional.
3-5 years of lag-period between investment and actual network capacity boost.
 In Jan 2015 AWS-3 spectrum auction, AT&T spent more than $18-billion to get ~20MHz of airwaves [1].
 This will boost AT&T’s downlink spectrum for LTE deployment from an existing approx. 40MHz to 50MHz
in most metro cities [2].
 AT&T plans to start rolling out AWS-3 based network in 2017-2018 [1].
[1] http://www.fiercewireless.com/story/aws-3-auction-results-att-leads-182b-verizon-104b-dish-10b-and-t-mobile-18b/2015-01-30
[2] https://s3.amazonaws.com/assets.fiercemarkets.net/public/007-Telecom/ATTSpectrum2.jpg
AWS-3
2015 2016 2017 2018
$18.2B
spectrum
purchase
Commercial
Launch
Device & Network
Equipment
Development
Network
Optimization

5. BOMA can provide Capacity
Relief to Congested 4G LTE
Networks NOW
and at a fraction of Cost.
 BOMA [1-2] i.e. “Building Block Sparse Constellation based Orthogonal Multiple Access” is a ground
breaking air interface technique that can easily boost LTE network capacity by downloading simple
software patches in the eNB and the mobile devices.
2016 2017 2018 2019 2020
BOMA
~ 6 months of
Proprietary/Pre-
Standard release
Software Patch
Development &
Testing
Commercial
Launch
New Spectrum/
Densification/
5G candidate
Features
Commercial
Launch
Site & Backhaul Acquisition, Standardization, Chipset & eNB
Hardware Development, Network optimization
[1]US Patent 8,077,790-”Tiled-building-lock trellis encoders,” Eric M. Dowling and John P. Fonseka
[2] USPTO Application #14/999,006 – M. Ahsan Naim and John P. Fonseka -- pending
50-60%
Downlink
Capacity boost

6.  BOMA, through a simple software patch based upgrade in the LTE eNB and devices can boost
network capacity by 50%-60% over traditional OFDMA currently used in 4G-LTE.
[1]US Patent 8,077,790-”Tiled-building-lock trellis encoders,” Eric M. Dowling and John P. Fonseka
[2] USPTO Application #14/999,006 – M. Ahsan Naim and John P. Fonseka -- pending
Salient Features of BOMA
Software (Patch
based) Change
• BOMA requires only minimal software changes in the LTE eNB
and handsets to work.
• No hardware/network changes are required for BOMA; hence
network capacity gain is achieved at a fraction of the cost.
Huge CAPEX savings.
Lag-period • Compared to other capacity augmentation strategies that
require 3-5 years, a simple software patch for BOMA can be
developed and deployed in 3-6 months time frame.
50%-60% capacity boost
NOW.
Compatibility
with 4G-LTE
• BOMA is fully compatible with 4G-LTE. It can be treated as an
enhancement of 4G-LTE.
Minimal changes to existing
4G-LTE network.
Frequency
Bands
• BOMA is implementable in all frequency bands i.e. Low,
Medium & High frequency bands.
Capacity boost in all bands
from 600MHz to mm-waves.
Average Capacity boost from BOMA
in different propagation environments.

8.  4G LTE uses QPSK, 16QAM and 64QAM (256QAM under very good signal conditions)
as modulation schemes to carry 2, 4 and 6 (8) bits of user data with each symbol
respectively.
256QAM
8 bits/symbol
QPSK
16QAM
64 QAM
256QAM
QPSK (2bits/symbol)
is used under weak
channel conditions
such as cell edge
As the quality of channel
improves (closer to base
station), the size of
constellation is
increased.

9. ….
 A loaded LTE carrier (such as during busy hours) typically serves multiple mobile users
with different channel condition.
 Air interface resources i.e. PRBs of the carrier are shared between mobile users with
different modulation schemes.
QPSK
16QAM
64 QAM
256QAM
LTE Carrier
Bits/Symbol
QPSK
Users
256QAM
Users
16QAM
Users
64QAM
Users
[1] For simplicity, transmit diversity/rank 1/single stream transmission is assumed but Concept can also be generalized for other LTE transmission modes.
𝑨𝑽𝑮 𝑺𝑬 =
𝟐 × 𝑷𝑹𝑩 𝑸𝑷𝑺𝑲 + 𝟒 × 𝑷𝑹𝑩 𝟏𝟔𝑸𝑨𝑴 + 𝟔 × 𝑷𝑹𝑩 𝟔𝟒𝑸𝑨𝑴 + 𝟖 × 𝑷𝑹𝑩 𝟐𝟓𝟔𝑸𝑨𝑴
𝑷𝑹𝑩 𝑸𝑷𝑺𝑲 + 𝑷𝑹𝑩 𝟏𝟔𝑸𝑨𝑴 + 𝑷𝑹𝑩 𝟔𝟒𝑸𝑨𝑴 + 𝑷𝑹𝑩 𝟐𝟓𝟔𝑸𝑨𝑴
𝑷𝑹𝑩 𝑸𝑷𝑺𝑲 𝑷𝑹𝑩 𝟏𝟔𝑸𝑨𝑴𝑷𝑹𝑩 𝟔𝟒𝑸𝑨𝑴 𝑷𝑹𝑩 𝟐𝟓𝟔𝑸𝑨𝑴

10.  BOMA uses concept of sparse constellation to increase the average SE of the LTE carrier.
 A Sparse constellation has the same/similar minimum Euclidean distance separation
between constellation points as that of a standard constellation but contains only a
subset of all constellation points as shown in few example figures below.
Standard 16QAM
4-bits per modulation Symbol
16QAM based Sparse Constellation
3-bits per modulation Symbol
Standard 64QAM
6-bits per modulation Symbol
64QAM based Sparse Constellation
4-bits per modulation Symbol
Standard 256QAM
8-bits per modulation Symbol
256QAM based Sparse Constellation
4-bits per modulation Symbol
 Both Standard and its corresponding
Sparse constellation require similar
channel quality (SINR) for similar
performance (BLER) due to similar
minimum Euclidean distance between
constellation points.
 However compared to standard
constellation, a sparse constellation
carries fewer data bits in each symbol.
No hardware change is needed
to generate these sparse
constellations by existing LTE
transmitters (eNB).

11.  In order to understand BOMA, lets compare it with OFDMA in a two-user (U1, U2) scenario in an LTE
carrier, U1 with QPSK based transmission and U2 with 64 QAM based transmission.
OFDMA (LTE/LTE-A)
LTE/LTE-A system with OFDMA assigns:
 U1 with a PRB in which each RE(resource element) carries 2 bits of data using
QPSK constellation.
 U2 with second PRB in which each RE carries 6 bits of data using 64QAM
constellation.
 Here 𝐴𝑉𝐺 𝑆𝐸 =
2×1+6×1
2
= 𝟒 𝒃𝒊𝒕𝒔/𝒔𝒚𝒎𝒃𝒐𝒍
QPSK
16QAM
64 QAM
256QAMU1
U2

12. BOMA
LTE/LTE-A system with BOMA assigns:
 U1 with a PRB in which each RE(resource element) carries a shared Tiled-Building Block
constellation(aka Sparse constellation) formed in two steps:
 Step A: Select a small QPSK building block (BB) constellation (based on 64QAM
spacing) from two bits of U2
 Step B: Place four copies of the BB symmetrically in 4 quadrants as shown in figure
above. These four copies referred to as tiles are assigned the four combinations of
the two bits from U1
 U2 with second PRB in which each RE carries 6 bits of data using 64QAM constellation.
 Here 𝐴𝑉𝐺 𝑆𝐸 =
(2+2)×1+6×1
2
= 𝟓 𝒃𝒊𝒕𝒔/𝒔𝒚𝒎𝒃𝒐𝒍
QPSK
16QAM
64 QAM
256QAMU1
U2
Extra Bits for U2

13.  Compared to the standard OFDMA in a two-user (U1, U2) scenario in LTE where a carrier transmits a
total of 8 bits from U1 & U2 in 2 REs, BOMA using shared TBB transmits 10 bits in the same 2 REs for
U1 & U2 as shown below.
 Hence for this example, avg. bits per RE increases from 4 to 5 i.e. gain of 25% over LTE.
U1 Data Bit Stream (QPSK User) 0 0 1 0 1 1 1 0
U2 Data Bit Stream (64QAM User) 1 0 1 1 1 1 0 0
1st RE (Shared Tiled-Building Block Constellation)
A point is selected
for transmission
based on 2 data bits
in U1 Bits Stream
and 2 data bits in U2
Bits Stream on
shared TBB
2nd RE (Standard 64-QAM)
A point is selected
for transmission
based on separate 6
data bits in U2 Bits
Stream on standard
64-QAM
0 1 0 0 1 1 0 1
1 1 1 1 0 0 0 0
……
……

14. QPSK region
16QAM region
64QAM region
 QPSK region user extracts its two bits by detecting the quadrant of the received signal.
 This corresponds to 2 MSBs (most significant bits) of the 4 bit TBB constellation point label.
 Note that bit labels of 2 MSBs in TBB remains unchanged within each quadrant.
 64QAM region user extracts its own two bits by detecting one of the 4 points within a quadrant i.e. building block.
 This corresponds to 2 LSBs (least significant bits) of the 4 bit TBB constellation point label.

15.  As shown in figure below, only a minor change in detection i.e. Bit Level Log-Likelihood
Ratio Computation is needed. There is no change needed in the turbo decoder part of
the receiver.
No hardware change is needed
to update Bit Level Log-
Likelihood Ratio Computation
by existing LTE receiver (UE).
A simple software update is
sufficient!

16. 3GPP parameter based simulation shows BOMA increase
downlink average spectral efficiency by 50-60% in urban macro,
urban micro and rural morphologies.
If you are interested in learning more about technical details on
how BOMA pairs users with different modulation schemes
(QPSK,16QAM, 64QAM, 256QAM), system capacity gain and
performance of LTE Network with BOMA, please contact us and
ask for BOMA whitepaper.
Contact Info:
M. Ahsan Naim, Ph.D
Co-Founder, Trellis Link
ahsan@trellislink.com

17. About US
Trellis Link, LLC is recently formed innovation and technology transfer company focusing on improving spectral efficiencies and
energy efficiencies in 4G and 5G communications networks. Trellis Link’s improvements allow network operators to service more
users and alleviate congestion in the networks they already have invested in or in the new networks they are fielding. Trellis Link
LLC has patented technology, called BOMA, that is able to increase the OFDMA downlink efficiency by roughly 50-60% in current
4G LTE networks. This same technology can be applied to improve spectral efficiencies in next generation 5G networks as
well. Trellis Link’s main focus is moving BOMA from the laboratory to the field.
Trellis link supplies consulting and technology transfer services to help its partners move BOMA into carrier networks
infrastructure equipment and into mobile units.
Trellis link continues to perform research and development to develop related technologies to work with BOMA and to further
help mobile networks increase the network coverage, capacity and number of users they can support with their existing and future
networks in a fixed amount of spectrum.