IEEE C802.16m-08/562
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Clarification on Possible Bandwidth Aggregation for Multi-carrier MS in IEEE 802.16m
Date
Submitted
2008-07-07
Source(s)
I-Kang Fu, Pei-Kai Liao, Paul Cheng
MediaTek Inc.
IK.Fu@mediatek.com
No.1, Dusing Rd. 1, Hsinchu Science
Park, Hsinchu, Taiwan, R.O.C.
Re:
IEEE 802.16m-08/024, “Call for Comments and Contributions on Project 802.16m System
Description Document (SDD)”
- Comments on P802.16m SDD
Abstract
This contribution provides several examples on possible MS transceiver architecture for multicarrier support in IEEE 802.16m system. It shows that there are different ways to aggregate
multi-carrier bandwidth, which corresponds to different receiver bandwidths.
Purpose
For TGm discussion and adoption on proposed text revision
Notice
Release
Patent
Policy
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1
IEEE C802.16m-08/562
Clarification on Possible Bandwidth Aggregation for
Multi-carrier MS in IEEE 802.16m
I-Kang Fu, Pei-Kai Liao, Paul Cheng
MediaTek Inc.
I. Introduction
In order to support multi-carrier operations in IEEE 802.16m system, the MS need to be capable to receive
and transmit the radio signals over different RF carriers at the same time. In addition, the MS may also need to
transmit or receive signal over the guard sub-carriers when contiguous RF carriers are operated by the same
system. In order to support multi-carrier operation and data transmission over guard sub-carriers, a virtual multicarrier technique was proposed [1] to utilize larger size FFT (i.e. 2048) to receive the radio signals over adjacent
RF carriers and the guard sub-carriers for post-processing.
The main objective of the design in [1] is expected to flexibly transmit/receive data over primary carrier,
secondary carrier and guard sub-carriers, and it’s actually a reasonable design. The main potential concern on
such transceiver architecture design is that it needs a symmetric frame structure layout as the example directed
in [2], so that the receiver does not need to adjust its RF center frequency when utilizing additional secondary
carriers and guard sub-carriers at both side. Unfortunately the legacy system does not follow such symmetric
frame structure layout for system deployment and such requirement on symmetric frame structure layout may
result in backward compatibility problem since 16e system is expected to be co-deployed with 16m system for a
period of time. The potential concern on frame structure is explained by Fig.1.
Can perform backward
compatibility only in TDM manner Frame structure layout proposed in [2] for
(higher restriction, less flexibility)
supporting the receiver architecture in [1]
Center frequency of
16m MS receiver
Center frequency of
16e MS receiver
20MHz
10MHz
10MHz
5MHz
10MHz
time
Legacy Zone
16m Zone
Fig.1 Potential concern on the frame structure layout proposed in [2] due to inefficient backward compatibility
II. Possible Transceiver Architecture for Multi-carrier Support
There are different kinds of transceiver architecture to realize multi-carrier operation for IEEE 802.16m, one
of the examples is given in Fig.2.
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IEEE C802.16m-08/562
Transmitter
Receiver
Multi-carrier
Controller
RF1
PHY1
PHY2
RF2
RF2
PHY2
PHY3
RF3
RF3
PHY4
RF4
RF4
Multiplexer
RF1
PHY3
Common MAC
PHY1
Multiplexer
Common MAC
Multi-carrier
Controller
PHY4
Fig.2 Flexible MS transceiver architecture to support multi-carrier operation
Take Fig.2 for example, the transceiver may equip with multiple RF modules, multiple PHY and a common
MAC entities. In response to different system operation, the transceiver can be flexibly configured for different
transmission scheme. Fig.3 shows an example to support single carrier 4x4 MIMO transmission by multiplexing
the MIMO signal from PHY1 to multiple RF modules as the most common case.
Configuration I:
Single Carrier 4x4 MIMO
Multi-carrier
Controller
Transmitter
PHY1
RF1
Receiver
RF1
RF2
f0
f0
RF3
RF3
f0
PHY4
PHY2
PHY3
f0
RF4
RF4
PHY4
Radio signal transmission with center frequency f0
Fig.3 Configure the transceiver for single carrier 4x4 MIMO transmission
3
Common MAC
Multiplexer
f0
RF2
PHY3
PHY1
Multiplexer
Common MAC
f0
PHY2
Multi-carrier
Controller
f0
f0
IEEE C802.16m-08/562
In addition, when multiple RF carriers are available in IEEE 802.16m system, the MS may also be configured
to support 2x2 MIMO transmission scheme in two different RF carriers as shown in Fig.4. On the other hand,
the MS may also be configured to support SISI transmission in four different RF carriers as shown in Fig.5.
Configuration II:
Multi-Carrier 2x2 MIMO
Multi-carrier
Controller
Transmitter
PHY1
RF1
Receiver
f0
RF1
RF2
f1
f1
RF3
RF3
f1
PHY4
PHY2
PHY3
Common MAC
Multiplexer
f0
RF2
PHY3
PHY1
Multiplexer
Common MAC
f0
PHY2
Multi-carrier
Controller
f0
f1
RF4
RF4
PHY4
Radio signal transmission with center frequency f0
Radio signal transmission with center frequency f1
Fig.4 Configure the MS transceiver for multi-carrier 2x2 MIMO transmission
Multi-carrier
Controller
Transmitter
PHY1
RF1
PHY4
f0
f0
Adaptive Multi-carrier Controller
PHY3
Multi-carrier
Controller
RF1
f1
PHY1
f1
RF2
RF2
f2
f2
RF3
RF3
f3
f3
RF4
RF4
PHY2
PHY3
PHY4
Radio signal transmission with center frequency f0
Radio signal transmission with center frequency f1
Radio signal transmission with center frequency f2
Radio signal transmission with center frequency f3
Fig.5 Configure the MS transceiver for multi-carrier SISO transmission
4
Common MAC
PHY2
Receiver
Adaptive Multi-carrier Controller
Common MAC
Configuration III:
Multi-Carrier SISO
IEEE C802.16m-08/562
For the examples from Fig.2 to Fig.5, this multi-carrier transceiver is actually an aggregation of multiple
single-carrier transceivers. For this case, the bandwidth of each single carrier transceiver can be the same as
legacy system for easy backward compatibility. When transmit/receive the radio signal over the guard subcarriers, the RF center frequency can be adjusted to the guard sub-carrier location. Another example on the way
to transmit/receive data over guard sub-carriers is given in C802.16m-08/561.
In summary, there may be many different kinds of bandwidth aggregation for the IEEE 802.16m multi-carrier
MS. The current drawing in Fig.18 in P802.16m SDD is confusing the multi-carrier MS with multiple
bandwidth aggregation with the single carrier MS. Therefore, the drawing shall be revised to prevent possible
misleading.
III. Text Proposal
-----------------------------------------------------------Start of the Text--------------------------------------------------------[Adopt the following figure to replace the Fig.18 in IEEE 802.16m-08/003r3]
Single
Carrier Multicarrier MSs
MSs
RFC3
Superframe
Superframe
header
RFC1
RFC2
.
.
.
SF
0
F0
SF
1
F1
SF
2
SF
3
F2
SF
4
SF
5
SF
6
F3
SF
7
Figure 18 Example of the proposed frame structure to support multi-carrier operation
------------------------------------------------------------End of the Text--------------------------------------------------------Reference
[1] Hujin Yin et al, ”Virtual Multi-Carrier Operation for IEEE 802.16m,” S802.16m-08/364r1, May 2008.
[2] Sassan Ahmadi et al, “A Multi-Bandwidth Terminal Support Scheme for IEEE 802.16m Systems,”
C802.16m-08/402r2, May 2008.
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