IEEE C802.16p-11/0034r1
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Group-based Allocation of Random Access Resources
Date
Submitted
2011-06-03
Source(s)
Andreas Maeder, Peter Rost, Hassan
Alkanani, Nader Zein, Xavier Perez-Costa
NEC
E-mail: andreas.maeder@neclab.eu
Chun-Yen Hsu, Yi-Ting Lin, Chiu-Wen
Chen
III
hcy@iii.org.tw
Re:
IEEE 802.16p CfC on AWD
Abstract
Proposal to introduce group-based allocation of random access resources
Purpose
To be discussed and adopted by TGp
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Notice
Release
Patent
Policy
Group-based Allocation of Random Access Resources
Andreas Maeder, Peter Rost, Hassan Alkanani, Nader Zein, Xavier Perez-Costa
NEC
Chun-Yen Hsu, Yi-Ting Lin, Chiu-Wen Chen
III
Motivation
One of the main issues of M2M traffic is the potentially very large number of devices which compete for
random access resources [1]. Although the current 802.16m draft standard [2] provides mechanism for access
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IEEE C802.16p-11/0034r1
priority, they may be insufficient to prevent a significant impact of M2M communication on human-based
traffic. Furthermore, M2M traffic is aside from the estimated small traffic volume quite heterogeneous in terms
of traffic characteristics. For example, smart-metering traffic is expected to occur periodically from a large
number of devices with relatively low requirements on message delay and small message sizes. In contrast,
traffic based on extrinsic factors such as e-health or vehicular communications occur infrequently, but possibly
with high QoS requirements.
Thus, the main challenges in this context are to
- prevent QoS degradation of human based communication attempts,
- enable a clean and easy solution to parameterize different classes of M2M traffic, and
- do this without the necessity to retransmit too often for power saving.
Several possibilities for congestion control and prioritization have been proposed in the rapporteur groups for
TGp, summarized in [3] and [4]. One possibility is to modify the ranging or bandwidth request mechanisms
introduce time dispersion either by explicit signaling or by introduction of probability factors. However, this
method has the disadvantage that still all devices are competing for the same resources, and that
parameterization is difficult since different device classes (including human-based communication) are
interfering with each other. Therefore, the number of communication attempts is increasing, leading to
increased power consumption of the M2M devices. Additionally, the ABS has to provide additional resources
quickly enough in case of sudden traffic peaks to maintain QoS guarantees, i.e. it has to estimate the aggregated
traffic rate of all M2M devices and adjust the random access resources accordingly.
We propose the concept of dedicated resource assignments for device groups in order to address the
aforementioned challenges. This means that a certain number of radio resources are exclusively reserved for
M2M traffic classes or device classes, such that
- competition for random access resources is only existing within an M2M group for easy and isolated
parameterization. Ranging and BRCH codes can be re-used for several groups.
- human-based communication is clearly separated from M2M traffic.
- the ABS can react quickly to traffic peaks and assign resources accordingly, thus avoiding wastage of
resources.
- M2M devices can be grouped according to traffic and device profiles and according to other properties
such as path loss in order to enable more power-efficient communication.
- no modification of the existing 802.16m priority mechanism intended for human-based communication
is necessary.
Dedicated random access resource assignments implicitly enable time- and frequency dispersion of random
access attempts. Random access resource can be allocated periodically to M2M groups with lower delay
requirements such that shortage of uplink resources during peak traffic times is avoided. It is therefore
equivalent to the statistical approach of reduced access probabilities, but with the advantage that interference
between different groups is effectively avoided.
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IEEE C802.16p-11/0034r1
Dedicated resources for group2
Dedicated resources
for group 1
time (h)
M2M group 1
M2M group2
Figure 1: Group random access resource assignments for bandwidth request channels.
Figure 1 illustrates the proposed mechanism of dedicated random access resources on high level. Two M2M
groups are deployed in the coverage area of an ABS. Both groups have a periodic traffic pattern, where the
period of group 1 is smaller than the period of group 2. The ABS assigns random access resources (i.e. ranging
and/or bandwidth request channels) if the respective devices are going to access the channel according to ther
traffic pattern. Note that this also can be interpreted as an implicit access control and a method to introduce time
dispersion: if devices are only allowed to access dedicated resources, resources can be assigned such that time
spreading is achieved.
Implementation
Implementation of dedicated random access resources should be done efficiently and without any large
modifications on the existing (draft) standards. The following text should be seen as a contribution for
discussion between TGp members on how to achieve group-based random access allocations.
Consider a system with K different groups of M2M devices served by a single ABS. Random access resource
(i.e. ranging channels and bandwidth request channels) are associated uniquely to each group. Thus, each group
is isolated from the other groups.
- Group assignments may be based on the existing Group IDs defined in [2] with a modified AAI-GRPCFG message.
- Alternatively, as also specified in [2], group assignments can be pre-provisioned to the AMS.
- For BRCH assignment, the AAI-DSx messages can be modified to carry information about group-based
BR channel assignments.
- For network re-entry, the Broadcast Assignment A-MAP IE can be extended to carry information about
group-based ranging opportunities.
References
[1] IEEE, “IEEE 802.16p-10/0004r2; IEEE 802.16p Machine to Machine (M2M) System Requirements
Document (SRD) (initial working document revised)”, Jan. 2011
[2] IEEE, “IEEE P802.16m/D11; Part 16: Air Interface for Broadband Wireless Access Systems; Advanced
Air Interface”, Jan. 2011
[3] IEEE, “C802.16p-11/0001; IEEE 802.16p Machine to Machine (M2M): Proposed Text from Large number
of devices Rapporteur Group”, Mar. 2011
[4] IEEE, “C802.16p-11/0002; IEEE 802.16p Machine to Machine (M2M): Proposed Text from Power Saving
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IEEE C802.16p-11/0034r1
(PWR) Rapporteur Group”, Mar. 2011
Proposed text
Remedy 1:
[add the following text into the current 802.16p AWD]
------------------------------------------------------- Text Start ----------------------------------------------------
16.2.11.1.1 Contention-based random access bandwidth request
M2M devices may be restricted to use dedicated BR opportunities assigned to an M2M group.
------------------------------------------------------- Text End ----------------------------------------------------
Remedy 2:
[add the following text into the current 802.16p AWD]
------------------------------------------------------- Text Start ----------------------------------------------------
16.2.18.5 Network reentry from idle mode
An ABS may assign dedicated ranging opportunities to an M2M group for network re-entry.
16.2.16 Periodic Ranging
16.2.16.x Ranging allocation for large numbers of machine to machine devices
Dedicated ranging opportunities may be allocated for specific M2M groups. If dedicated ranging opportunities
are allocated to a group of M2M devices, said M2M devices shall not send ranging signals on the opportunities
which has been allocated to AMSs or MSs.
------------------------------------------------------- Text End ----------------------------------------------------
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