IEEE C802.16p-11/0041
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Channel Access Schemes for Supporting Large Number of M2M devices
Date
Submitted
2011-03-13
Source(s)
Jia-Hao Wu, Yu-Tao Hsieh, Ping-Heng
Kuo, Pang-An Ting
Voice:
E-mail: ythsieh@itri.org.tw
E-mail: Jefferywu@itri.org.tw
ITRI
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Re:
IEEE 802.16p-10/0018
Abstract
This contribution is to provide uplink data channel access scheme for M2M devices.
Purpose
To be discussed and agreed in IEEE 802.16p AWD
Notice
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Channel Access Schemes Supporting for Large Number of M2M
Devices
Jia-Hao Wu, Yu-Tao Hsieh, Ping-Heng Kuo and Pang-An Ting
ITRI
1. Introduction
Recently, machine-to-machine (M2M) communication has gained much attention in various standard bodies
due to its envisioned broad applications in our life. For example, the M2M services may include personal
healthcare, traffic monitor and control, criminal surveillance, smart grid and so on. Many of them demand a
ubiquitous wireless access to ease its practical applications. However, supporting radio channel access of huge
amount of M2M devices over original cellular network may become a challenging problem. Furthermore,
different M2M applications may have diverse service requirements and it is very desirable to mostly support
M2M data transmission over existing IEEE 802.16 air interface. In this contribution, we would like to propose
data channel access and data allocation scheme for the coexistence of M2M and cellular MS.
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2. Proposed data channel access schemes
In order to support data transmission of a large number of M2M devices, we desire to propose an efficient
technique to accommodate coexistence of a great deal of M2M devices and 16e/16m mobile stations (MS) in
cellular systems. Our main theme is to propose an efficient physical layer channel access scheme that can
support the largest number of M2M devices (or connections) with the least detriment of the original cellular MS.
In addition, there are different service requirements for different M2M applications. For example, the
emergency report of a remote surveillance system may be delay sensitive while some acknowledgement
message can be delay tolerant. The M2M message with multimedia content may result in larger burst size than
the message which contains only a few bits for devices’ status report purposes. Considering the diverse service
requirement nature of M2M transmission, a flexible channel access scheme may be preferable. We categorize
the M2M data transmission channel as following:
(1) Reserved and dedicated channel: the BS reserves certain resource blocks (RB) for the specific M2M
transmissions. There is no mutual interference between M2M devices and cellular mobile stations.
(2) Reserved but shared channel: the BS reserves certain set of RB for the M2M transmissions. Many M2M
devices share the same set of RB. In consequence, there may be collisions between different M2M
transmissions. But the cellular MS will not be interfered by M2M traffic.
(3) Superimposed channel: the BS would not separate the time-frequency channels for cellular mobile stations
and M2M devices. Instead, the M2M bursts would be allocated to RB which has already been occupied by
mobile stations. Thus, M2M traffic and cellular mobile stations’ bursts are superimposed. Besides, in order
to support coherent detection at the BS, the pilot stream number in the superimposed RB shall be no less
than the total number of 16e/16m MS and M2M data stream number.
It shall be mentioned that the superimposed channels enhance the flexibility of channel allocation especially
when the cellular network needs to simultaneously support the transmission of a large number of M2M devices
and cellular MS’s traffic.
Figure 1 shows an exemplary OFDMA channel allocation for M2M devices and cellular MS. In the figure, we
show an example of how M2M devices share the radio channels with cellular MSs. The data transmitted from
M2M and MS are overlapped in the rank-sufficient and rank-deficient superimposed channels. Note that the
time-frequency resource blocks shown here are not necessarily to be physically contiguous in time or frequency
domain. In addition, an explanative illustration is given to distinguish the rank sufficient and rank deficient
superimposed channels.
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IEEE C802.16p-11/0041
Cellular
MSs
Cellular MS data
M2M
devices
Dedicated
Cellular
MS
Uplink
Channel
Rank
Sufficient
Superimposed
Channel
Rank sufficient
superimposed
transmission
Rank
Defficient
Superimposed
Channel
Cellular
MSs
M2M
devices
Reserved but shared
M2M Channel
Reserved and Dedicated
M2M Channel
Time-Frequency Resource
BS
BS
Rank deficient
superimposed
transmission
M2M data
Fig. 1 Illustration of the radio resource sharing scheme for cellular MS and M2M devices
The data channel access schemes described above provide different link qualities and transmission delays. In
order to support data bursts of a large number of M2M devices without causing significant impacts on cellular
MSs, we need to allocate M2M bursts on those channels according to following factors:
(1) Cellular network channel load:
When cellular network load is not burdensome, the BS can assign M2M data bursts to the reserved shared
channel or reserved dedicated channel. On the contrary, when cellular network is heavily loaded, the BS may
assign some part of M2M data traffic to the superimposed channels so that the radio resource can be shared by
original cellular 16e/16m MSs and M2M devices. Consequently, M2M devices can avoid long waiting time for
available reserved M2M channels
(2) M2M service requirements:
As mentioned before, the M2M service applications are diverse. Different M2M services correspond to
different service requirements such as (A) M2M service delay, (B) M2M burst size (or packet size, data rate)
and (C) M2M transmission reliability (or burst error rate). In order to meet such various service requirements,
the BS shall allocate various M2M traffic to the aforementioned channels that can mostly fulfill those service
requirements.
(3) Received M2M signal strength indication (M2M RSSI):
The received M2M signal strength at the BS may depend on the channel gain (large scale and small scale
fading) and the M2M device transmission power. When allocating M2M traffic to a certain channel, the BS
should consider the M2M RSSI or its derivatives such as M2M signal to interference and noise ratio (SINR).
Furthermore, the M2M signal strength should be measured by the BS directly or may be fed back by M2M
devices through certain feedback channel.
Generally speaking, the burst sizes of most M2M traffic are small compared to the data packet size of
cellular voice and data communications. Besides, in order to provide a longer battery life for M2M devices, the
low power transmission is very desirable. Combining these two features, the low rate and low power M2M data
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can be superimposed on the original cellular 16e/16m MS data symbols even in the rank deficient channel
conditions. Figure 2 presents an illustration of this superposition based channel access scheme. In this figure,
low rate low power M2M data symbols may be allocated repeatedly to multiple subcarriers (represented by S1,
S2 and S3) which have been assigned to high rate high power cellular MS data (represented by D1~ D27)
symbols.
time
Freq.
D1
D10
Cellular MS
D19
S1
S1
D11
D20
S1
Low-rate
M2M Devices
D2
D12
D21
S1
S1
S1
D3
D13
D22
S1
S1
S1
D4
S2
D14
D23
S2
S2
D5
D15
D24
S2
S2
S2
D6
D16
D25
S2
S2
S2
D7
D17
D26
S3
S3
S3
D8
D18
D27
S3
S3
S3
D9
S3
S3
S3
Fig. 2 Data allocation scheme for superimposed channel
3. Proposed Text
Adopt the following text modifications on the last page of document IEEE 802.16p-11/0001:
============================== Proposed Text Modifications ============================
[16.3.X Support for large number of M2M devices
To support data transmissions of a large number of M2M devices, the 802.16p may support BS shall allow
for uplink superimposed transmission of M2M and AMS superimposed transmission data in uplink. The
superimposed transmission can be also carried out in rank-sufficient or rank-deficient MIMO conditions.
Furthermore, tThe M2M data symbols could may be repeatedly transmitted over multiple subcarriers or
OFDMA symbols, even in the superimposed channel, to maintain the data reliability facilitate reliable
transmission of M2M data bursts.]
============================== Proposed Text End ==================================
4. Reference
[1] IEEE 802.16p-10/0004r2: IEEE 802.16p Machine to Machine (M2M) System Requirements Document
(SRD)
[2] IEEE 802.16p-10/0005r1: Machine to Machine (M2M) Communications Technical Report
[3] IEEE P802.16m/D11, Draft Amendment to IEEE Standard for Local and Metropolitan area Networks
[4] IEEE C802.16p-11/0001, IEEE 802.16p Machine to Machine (M2M): Proposed Text from Large number of
devices Rapporteur Group, Feb. 2011.
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