1. I-Kang Fu, Paul Cheng, MediaTek
IEEE MEDIA INDEPENDENT HANDOVER
DCN: hwnm
Title: Multi-Radio Integration for Heterog. Networks
Date Submitted: May 13, 2010
Presented to Heterogeneous Wireless Networks Mgmt. SG at IEEE session #38 in Bangalore
Authors or Source(s):
I-Kang Fu, Paul Cheng, MediaTek
Abstract: Identify some issues in heterogeneous networks from a device-vendor perspective

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3. Introduction
Huge demand on broadband wireless access will be stimulated in 4G era
~1Gbps peak transmission rate in wireless network can provide users similar experience as in wireline network
Peak transmission rate should be no longer a critical problem after 4G era
Most of the existing Internet services can be carried by 4G wireless networks
Mobile Internet becomes reality and further stimulate more advanced services and substantially change the human life again
The network capacity will soon be exhausted in next few years
The spectral efficiency is improved less than ×10, but the capacity demand is increased more than ×100.
4G deployment will not slow down but most likely to speed up the happen of this problem by stimulating many novel broadband services
Capacity exhaustion will be the most severe problem during the 4G and Beyond (B4G) era

4. Introduction
The most efficient solution is to increase spectrum allocation
The gain from spectral efficiency improvement becomes more and more marginal (e.g. increase MIMO order)
additional spectrum for the same system can certainly help
The required technology (i.e. multi-carrier) is already available in 4G systems (i.e. WiMAX 2.0 and LTE-Advanced)
More spectrum from different systems will also be helpful
New technology is required to achieve this objective in B4G era
Heterogeneous network integration is the most promising candidate
Average spectrum utilization in each country is poor today
Different operators and different systems cannot share their spectrum resources
The base station or access point distribution is different by each operator and system
Traffic access demand by user is random in time and in location, but the network coverage by specific operator or system may not always be best available.
But the spectrum resource by some other operator or network may be idle at the same time and the same location
New technology is desirable to enable intelligent radio resource sharing

5. Problem Discussion
Multiple radio access networks between information source and user
May be operated by the same air-interface (e.g. different operators)
Single tier network → can be resolved by existing roaming solution
May be operated by different air-interfaces
Heterogeneous network → new technologies are required to enable radio resource sharing

6. Problem Discussion
Two design perspective need to be considered when discussing heterogeneous network issues:
Network Integration
Multi-Radio Integration
Technology evolution may be categorized into three stages: (example)
Coexistence
Interference mitigation
Cooperation
Smart Internetworking
Cognition
Internetwork radio resource sharing

7. Multi-Radio Integration Challenges
Challenges to support heterogeneous network from device perspective
Stage 1: Interference mitigation for co-located multi-radio coexistence
Objective – mitigate the interference from co-located modem to improve modem performances
FDM based solution (i.e. filtering) may not work when the frequency channels are too close (e.g. between ISM band and 2.3GHz band)
Protocol based solution may be required under some scenario
Ongoing efforts in many different standard organizations
BB: Baseband module
RF: Radio Frequency module
ANT: Antenna module

8. Multi-Radio Integration Challenges
Challenges to support heterogeneous network from device perspective
Stage 2: Smart interworking for co-located multi-radio component sharing
Objective – efficient internetworking to help device maintain connections in multiple systems by shared hardware (e.g. RF module)
For example, new protocol to help device fast switching between two system without losing control signals.
Logical connection may still be maintained in parallel for service continuity

9. Multi-Radio Integration Challenges
Challenges to support heterogeneous network from device perspective
Stage 3: Intelligent spectrum sharing for cognition by fully integrated radio
Objective – optimize the radio (spectrum) resources among multi-tier heterogeneous network by minimizing the duplicated hardware functions (FFS)
Prevent unnecessary waste on spectrum resource, transmit power and processing power.

10. Summary
Heterogeneous Network is the most promising technology which can significantly resolve the capacity exhaustion problem in Beyond 4G era
New technology need to be developed both from network and device perspectives
Possible parameters exchange to facilitate physical layer and RF switching
Center frequency
Frame timing
PHY specific parameters (e.g. signal bandwidth)
Possible parameters exchange to facilitate MAC connection setup
Protocol version
Security context
MAC specific parameters (e.g. sleep/idle mode related parameters)