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 change the human life again
The network capacity will be exhausted very soon in next few years
The spectral efficiency is improved less than ×10, but the capacity demand is increased more than ×100.
The capacity will still be exhausted very soon even all the networks are upgraded with 4G air-interface
Capacity exhaustion will be the most severe problem during the 4G and Beyond (B4G) era

4. Introduction
Different candidate technologies can possibly help on capacity improvement
Heterogeneous network
Cooperative techniques
Advanced MIMO
etc.
Heterogeneous network may be the most promising candidate technology
The room for intra-system optimization (i.e. further increase spectral efficiency) will be bounded by multiple access interference (e.g. inter-cell)
However, the spectrum resources today are not efficiently utilized because different network may not be able to share spectrum resources with each other.
Because the traffic and network loading distribution is time variant, but operator need to deploy the network base on worse case.
This problem may be resolved without change of PHY but mostly by MAC enhancement

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 problems:
Network perspective
Device perspective
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.
Maintain logical connection may still be maintained in parallel if necessary

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
Development task may be categorized into multiple stages
Stage 1: Multi-radio & Heterogeneous Network Coexistence
Stage 2: Multi-radio & Heterogeneous Network Cooperation
Stage 3: Multi-radio & Heterogeneous Network Cognition
Recommendation
Consider the requirements both from multi-radio network and device perspectives within the scope of new project