IEEE C802.20-03/110
Project
IEEE 802.20 Working Group on Mobile Broadband Wireless Access
<http://grouper.ieee.org/groups/802/20/>
Title
Detailed Discussion of SRD issues
Date
Submitted
2003-11-11
Source(s)
John Humbert
6220 Sprint Parkway,
MS KSOPHD0504 - 5D276
Overland Park, KS 66251
Re:
System Requirements Document
Abstract
Detailed discussion of the issues that need to be resolved to get consensus
Purpose
Detailed issues discussion
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C802.20-03/110
Detailed Discussion of SRD
issues
John Humbert
11/11/03
-2-
SRD Status update
C802.20-03/110
• Open issues:
– System Architecture, Spectral Efficiency, Block
Assignments (formally Channel Bandwidth),
Duplexing, Aggregate Data Rates, Number
Simultaneous Active users, Latency, FER, Antenna
Diversity, Best Server Selection, QoS, Performance
under mobility & Delay Spread, MAC/PHY
Measurements, IP Level HO. 802.1Q Tagging, OA&M
support, MAC Complexity, Call Blocking, Priority
Access (new section), Multicarrier Support (new).
-3-
Support for Different Block
Assignments (4.1.3)
C802.20-03/110
• Questions as to whether or not a
Proposal needs to support all of the
block assignments.
– According to the Author's the intent was not
to specify a specific BW.
– -Need to verify language
-4-
Support for Different Block
Assignments (4.1.3)
C802.20-03/110
– The AI shall support deployment of 802.20 systems
in the following sized block assignments:
FDD
Assignments
2 x 1.25 MHz
2 x 5 MHz
2 x 10 MHz
2 x 20 MHz
TDD
Assignments
2.5 MHZ
5 MHZ
10 MHZ
20 MHz
40 MHz
The individual 802.20 AI proposals may optimize their MAC and
PHY designs for specific bandwidth and Duplexing schemes.
This section is not intended to specify a particular channel
bandwidth. Proposals do not need to fit into all block
assignments.
-5-
Sustained Spectral
Efficiency(4.1.2)
C802.20-03/110
• Should there be targets for Higher
speeds?
• Need to come to consensus on the
definition of a Cell.
– The current definition has it as one sector in
a 3 sector system and then treats an omni
antenna as 1 sector.
– The other definition combines all sectors
• Need to Clarify the definition of System
Bandwidth
-6-
Sustained Spectral Efficiency
(4.1.2)
• 4.1.2
C802.20-03/110
Spectral Efficiency (b/s/Hz/cell)
• Sustained spectral efficiency is computed in a loaded multicellular network setting. It is defined as the ratio of the
expected aggregate throughput (taking out all PHY/MAC
overhead) to all users in an interior cell divided by the system
bandwidth. The sustained spectral efficiency calculation shall
assume that users are distributed uniformly throughout the
network. For the purpose of evaluation, proposals should be
limited to at most three sectors to maintain consistency with
current deployment practices. The values of the number of
sectors and the number of antennas must be clearly disclosed
to allow for comparisons between various proposals. Proposed
minimum values are
– downlink > 2 b/s/Hz/sector @ 3km/hr
– uplink > 1 b/s/Hz/sector @ 3 km/hr
-7-
Sustained Spectral Efficiency
(4.1.2)
C802.20-03/110
•
4.1.2
Spectral Efficiency (b/s/Hz/cell)
•
Sustained spectral efficiency is computed in a loaded multi-cellular
network setting. It is defined as the ratio of the expected aggregate
throughput (taking out all PHY/MAC overhead) to all users in a sector
divided by the system bandwidth (the aggregate spectral allocation in
use across the entire system). The sustained spectral efficiency
calculation shall assume that users are distributed uniformly
throughout the network and shall include a specification of the
minimum expected data rate/user. A fair comparison of the spectral
efficiencies of different air interfaces can best be achieved for a single
specified baseline configuration.
To facilitate the subsequent evaluation of different proposals for the
802.20 air interface, the spectral efficiency of the 802.20 air interface
shall be quoted as b/s/Hz/sector for a three sector baseline
configuration. Within this subsequent evaluation, proposals may
submit respective deployment models over and beyond the base
configuration.
Consistent with the PAR requirement that is stated on a per cell basis
and the definitions shown in Appendix A, the sustained spectral
efficiency of the 802.20 air interface shall be greater than 1 -8b/s/Hz/sector.
TDD & FDD (4.1.4)
C802.20-03/110
• Do proposals need to one or both forms of
Duplexing?
• Neither the PAR, nor the 802.20 SRD (rev 8c)
provide an explicit requirement that
technology proposals support both FDD and
TDD modes. Thus, • It is reasonable to assume, that this is not a
requirement. i.e., proposals may support
either (FDD/TDD) or both. -- if this is the
consensus requirement, it should be clearly
stated in the SRD.
-9-
TDD & FDD (4.1.4)
C802.20-03/110
• Current Text
– The standard shall support both Frequency
Division Duplexing (FDD) and Time Division
Duplexing (TDD).
-An AI proposal may support either a
Frequency Division Duplexing or Time
Division Duplexing or both.
-10-
Aggregate Data Rates (4.1.6)
C802.20-03/110
• IS there a need to maintain same UL/DL ratio
between peak and aggregate data rates?
• Need to ensure the values in this section are
consistent with the PAR and other sections of
the SRD.
• Aggregate data rates depend on the overall
combination of coverage and aggregate
capacity and system deployment.
-11-
Aggregate Data Rates (4.1.6)
C802.20-03/110
• The aggregate data rate for downlink and
uplink shall be consistent with the spectral
efficiency. An example of a 5MHz FDD channel
is shown in Table 1 below.
Description
Outdoor to Indoor
Expected Aggregate
Data Rate
Downlink
Uplink
> 10 Mbps/Sector
> 5Mbps/Sector
-12-
C802.20-03/110
Number of Simultaneous Active
users (4.1.7)
• MAC has two types of traffic.
– One that is time critical (Voice/streaming)
and one that can accept delays (data). So
are we saying > 100 voice or > 100 of
some combination. If it is some
combination, we need to specify what the
ratio is.
-13-
C802.20-03/110
Number of Simultaneous Active
users (4.1.7)
• Current Text
– The system [MAC] should support > 100
simultaneous active users per [??
Mhz/sector] of [channel bw/sector. An
active user is a terminal that is registered
with a cell and is using or seeking to use air
link resources to receive and/or transmit
data within a short time interval (e.g.,
within 50 or 100 ms).
-14-
C802.20-03/110
Latency-ARQ Loop Delay (4.1.9)
• Is 10 ms the right value?
– If ACK/NACK information is transferred in a physical
frame. Limiting the delay within 10ms results in
limiting the size of a physical frame to less than
2.5ms.
– This requirement will highly restrict physical design
of MBWA.
– The size of a physical frame should be determined
considering not only delay factor but also many other
factors.
– Section needs to be modified based on Anna’s
input.
-15-
C802.20-03/110
Latency-ARQ Loop Delay (4.1.9)
• The AI shall minimize the round-trip times (RTT) and the
variation in RTT for acknowledgements, within a given QoS
traffic class. The RTT over the airlink for a MAC data frame
is defined here to be the duration from when a data frame
is received by the physical layer of the transmitter to the
time when an acknowledgment for that frame is received
by the transmitting station. The airlink MAC frame RTT,
which can also be called the “ARQ loop delay,” shall
be less than 10 ms. Fast acknowledgment of data
frames allows for retransmissions to occur quickly,
reducing the adverse impact of retransmissions on IP
packet throughput. This particularly improves the
performance of gaming, financial, and other real-time low
latency transactions.
-16-
Performance under mobility & C802.20-03/110
Delay Spread (4.2.3)
• During the meeting in Singapore, Jin-Weon Chang has
presented a contribution (C802.20-03/77, jointly by DS Park
& Joseph Cleveland) on the delay spread profiles for mobile
channels. In some of the channel models that were specified
by ITU, 3GPP or COST 259, the delay spread can be larger
than 10 microseconds. Thus, it may be too limited if the
future 802.20 system can only work in channel environments
that have delay spreads of 5 microseconds or less.
• The suggestion was to have a high-level requirement that
would ensure the system could perform satisfactorily in the
mobile channel environments, with a high enough probability,
without mentioning any parameter related to the channel
models.
• Specifying the link reliability by itself is difficult because it
naturally depends on the channels models employed and we
are not specifying these in the requirements document.
-17-
Performance under mobility & C802.20-03/110
Delay Spread (4.2.3)
• Current text:
– "The system should support a delay spread of at least 5
micro-seconds."
• Proposed Text
– "The system should support a delay spread contained
within the 802.20 channel models.
– The system should support a delay spread of at least 5
micro-seconds. The upper limit for comparing the
degradation caused by delay spread is bounded by the
channel models selected for 802.20.
– "The system should support a delay spread of at least 5
micro-seconds with 100% link Reliability.“
– "The system shall support a delay spread of at least 5
micro-seconds."
-18-
Antenna Diversity (4.1.11)
C802.20-03/110
• Is this section a duplication of section
4.1.10?
• The antenna number of Mobile Terminal
should not be defined in the
requirements Document.
• Need for the AI to support diversity
-19-
Antenna Diversity (4.1.11)
C802.20-03/110
• 4.1.10 Support for Multi Antenna Capabilities (Closed)
– Interconnectivity at the PHY/MAC will be provided at the Base
Station and/or the Mobile Terminal for advanced multi antenna
technologies to achieve higher effective data rates, user capacity,
cell sizes and reliability. As an example, MIMO.
• 4.1.11 Antenna Diversity
– Latest Proposal
• At a minimum, the Air Interface shall provide support for receive
diversity.
– Option 1
• At a minimum, both the Base Station and the Mobile Terminal shall
provide two element diversity. Diversity may be an integral part of an
advanced antenna solution.
– Option 2
• Delete Section – Duplicates requirements in Section 4.1.0
– Option 3
• The Base Station shall provide antenna diversity. Diversity may be an
integral part of an advanced antenna solution. Antenna diversity shall not
be a requirement of the mobile station.
– Option 4
•
The base station shall provide support for multiple antenna processing
-20-
802.1Q Tagging (4.5.2)
C802.20-03/110
• Specifies a particular architecture
• Next generation broadband wireless
networks need to support partnered
networks and consumer based retail mass
market purchase and enabling on line
network service provisioning models.
-21-
802.1Q Tagging (4.5.2)
C802.20-03/110
• Most recent Proposal
– 802.1Q tagging must be supported by the
system (such that network egress traffic can be
switched by a L2 device to the appropriate L2
termination device for managing backbone
traffic authentication vlans and or captive
portal redirection to enable purchase and
provision retail models or distinguish traffic for
wholesale partners in a wholesale
environment).
-22-
Priority Access (New)
C802.20-03/110
• Should this be part of QOS
functionality?
• Is this a requirement for 802.20?
• Needed for Emergency situations
-23-
Priority Access (New)
C802.20-03/110
• Most Recent Proposal
– The Air Interface shall provide priority
access to authorized Mobile Terminals.
-24-
IP level HO (4.5.1.1)
C802.20-03/110
• Further discussion required
– Contribution C802.20-03/95
– Other HO proposals
• Intra – 802.20
• Between Technology
-25-
IP level HO (4.5.1.1)
C802.20-03/110
• Current Proposal
– "802.20 shall support L2 to L3 communication of
helpful hints that can facilitate faster handoff
performance and other potential benefits based on the
use of such hints"
• Option1
• [Delete requirement]
• Option 2
– [In supporting high speed mobility in an all IP network,
the MBWA air interface shall be designed in a manner
that does not preclude the use of MobileIP or of
SimpleIP for the preservation of IP session state as a
subscriber's session is handed over from one base
station or sector to another. Multiple IP addresses
behind one terminal may also be supported.]
-26-
Mac Complexity Measures
(4.5.5)
C802.20-03/110
• Should this be a requirement?
– MAC complexity measures should not be
addressed by this requirements document.
Our driving goal must be to achieve the
performance of the PAR. Complexity
measures even, if they could be articulated
in this document, are not relevant when
compared to the overriding goal of
achieving performance for data
-27-
Mac Complexity Measures
(4.5.5)
C802.20-03/110
• Option 1
– Delete Section
• Option 2
– To make the MBWA technology
commercially feasible, it is necessary the
complexity is minimized at the MAC,
consistent with the goals defined for the
technologies. This section defines
complexity measures to be used in
estimating MAC complexity.
-28-
System Architecture (Section 3.1)
C802.20-03/110
• Associated Issues
– The current text limits architectures to
Point-to-multipoint.
– Need to allow other network topologies like
mash or a hybrid of Mesh and P-MP.
– Also language was proposed to require
support for Micro and Pico cells.
-29-
System Architecture(3.1)
C802.20-03/110
• Most Recent Proposal
– The 802.20 systems must be designed to provide
ubiquitous mobile broadband wireless access in a
cellular architecture. The system architecture must
be one of the following architectures:
1) Point to multipoint topology
2) Mesh network topology
3) Hybrid of both mesh and point to multipoint.
The 802.20 system must support non-line of sight
outdoor to indoor scenarios. The system must be
designed to enable a cellular architecture
(macro/micro/Pico cells) with allowance for indoor
penetration .
-30-
Other Open Sections
C802.20-03/110
• These sections are currently open, however there has
been little, if any, activity within the CG.
– Multi-carrier Support
– Call Blocking
• This will likely be removed as a requirement
– Mac/PHY Measurements
– Duplexing
– OA&M Support
– QOS (Sections 4.1.14 & 4.4.1)
– FER
– Best Server Selection
-31-