Re: [STDS-802-16] [802.16n][DC] Discussion on Usages and Frame Structure for DC
Hi Sungcheol and all,
REGARDING USE CASES:
I support the allowance of HR-MS direct communications and forwarding when both HR-MSs are within coverage of an infrastructure node. The reasons are:
- Enhancing reliability/robustness: the direct link between a pair of HR-MSs basically provides us with an alternative path. This path, when chosen properly (e.g., based on distance, channel quality), allows communications to happen at higher rate and/or lower probability of error, and/or lower transmit power. All these contribute to the higher reliability/robustness of an HR network. To me, it can even be argued that this mode of communications (when both HR-MSs are within coverage) is more reliability-relevant than the mode of coverage extension (when one HR-MS is outside of coverage). Coverage extension is like enhancing the capability of a network, rather than reliability/robustness. Of course, one can argue it in an opposite way, but I think all three coverage scenarios should be supported.
- Acceptable complexity: I believe that if someone provides a reasonable design to support HR-MS direct communication or forwarding under the two scenarios of no infrastructure node or only one HR-MS is within coverage, then a simpler design can always be derived to support the scenario when both HR-MSs are within coverage. In other words, if you have some mechanism to support a rather complicated use case, why don't you just simplify that to also support an easier use case? Take note that this simpler use case does provide reliability benefits.
REGARDING FRAME STRUCTURE:
For the spatial reuse of resource allocated to HR-MS direct transmissions, I am open to the possibility. However, as mentioned in previous email, I share Sungcheol's concern of interference mitigation. In fact, Eldad has also previously discussed this interference concern. To me, even without reusing allocated resource, controlling interference between HR-MSs direct communications and legacy transmissions (between HR-BS and HR-MS) is tough enough. Having said that, I do not see how reserving a fixed resource for HR-MS direct transmissions would better minimize interference, compared to the approach when BS allocates resource dynamically, but without two transmissions sharing (re-using) the same logical resource units.
Regarding TDM vs FDM, current approach in 16m is based on FDM (within each subframe). So FDM to me is a natural approach. However, I propose that we stick to the 16m subframe boundaries when doing resource allocation for HR-MS direct comm/forwarding. Do we have a strong reason/motivation for allocating a narrow band resource spanning several subframes for a HR-MS direct transmissions?
Best regards,
Anh Tuan
________________________________
From: Chang, Sungcheol [mailto:scchang@etri.re.kr]
Sent: Fri 4/8/2011 8:55 PM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: Re: [STDS-802-16] [802.16n][DC] Discussion on Usages and Frame Structure for DC
Dear Eldad and all,
REGARDING USE CASES:
From the 16n SRD document, we can consider three usage scenarios.
I can agree two use cases: 1) Infrastructure nodes are absent and 2) One HR-MS is associated with an infrastructure node and one or more other HR-MSs are out of coverage of an infrastructure node.
But, we need more discussion about both HR-MSs under an infrastructure node.
For the use case of both two HR-MS under an infrastructure node,
What is the motivation that 16n specification includes this use case?
As you knows, 16n specification is for reliability enhancement.
Is this usage case related to reliability enhancement?
I thank that the major gain of this use case is that resource usage efficiency increases using higher modulation scheme with good channel quality.
Can you tell me the motivation of this usage case?
REGARDING FRAME STRCUTRE:
I respond Eldad's questions as the follwings:
1) I think we don't allow that. If it is guaranteed that two HR-MSs are far enough, two HR-MSs may transmit on the same resources. However, how can it be guaranteed? Interference mitigation has been a challenging research topic. But I don't agree that 16n specification adapts interference management approaches because its complexity. (Do we consider direct communication among HR-MSs in the same cell? I am negative)
2) Generally I think that resource used for infrastructure communication is exclusive to resource for direct communication. From this agreement, we can extend resource usages if its algorithm is simple. Exclusive resource allocation guarantees that interference each other may be controlled easily.
3) We need fixed resources of direct communications for all cells if HR-MS may be at several radio environment cases including under infrastructure node, in absent of infrastructure not, and in the middle of infra-structure nodes. It is recommended that this fixed resource shall be as small as possible because the resource is not be used by infrastructure node for interference avoidance.
4) It depends on design. The fixed resource of direct communication is static and limits resources for infrastructure communications. To solve this problem, the fixed resource is reserved at minimum and additional resource information can broadcast on the fixed resource. Its additional resource may be quasi-static and cell specific if possible. How about two step resource of direct communication?
For frame structure of direct communication, we need discuss types of DC specific resources, TDM and FDM separations. TDM means that its bandwidth of DC specific resources is wideband. FDM means that narrowband resources can be reserved for DC specific resources. I prefer that the DC resources shall be allocated as narrowband because of its coverage enhancement. So I have a preference to FDM for DC specific resource separation. Is there any reason that DC specific resource shall be FDM in 16n specification based on 16m specification? (I understand that TDM is a way of DC specific resource allocation for 16e specification because diversity zone and AMC zone are exclusive in time domain)
We need to speed up e-mail discussion for usage and frame structure of direct communication.
I look forward to 16n participants' reply emails.
Best regards,
Sungcheol Chang, Ph.D.
Mobile Access Technology Research Team, ETRI
From: Zeira, Eldad [mailto:Eldad.Zeira@INTERDIGITAL.COM]
Sent: Wednesday, April 06, 2011 9:43 PM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: Re: [STDS-802-16] [802.16n][DC] Discussion on Usages and Frame Structure for DC
Hi All
Thanks, Sungcheol and Haiguang,
In order to keep same thread I'm commenting on both Sungcheol's email and Haiguang comment. Let's try to keep the number of threads to a minimum;
Regarding use cases:
I like Haiguang's proposal to separate the overview along SRD lines. To clarify what I think is the intent, I would like to modify that text (see below).
I also support Haiguang's statement that as the SRD doesn't discuss services then all scenarios should support all services.
Other than some minor editorials, the reasons for the suggested changes are as follows:
- AWD text shouldn't discuss usage which is up to implementation. We can discuss modes.
- I have used the term "infrastructure node" to refer to HR-BS or HR-RS.
- I have replaced "HR-MSs does not associate to HR-BS " with "Infrastructure nodes are absent". The latter is from the SRD, the former implies that HR-BS is present but the HR-MS ignore it which is not in the SRD.
The cleaned, revised text is therefore:
* Modes for HR-MS direct communication
- Both HR-MSs are associated with an infrastructure node.
- Infrastructure nodes are absent.
* Modes for HR-MS local forwarding
- One HR-MS is associated with an infrastructure node and one or more other HR-MSs are out of coverage of an infrastructure node.
Regarding frame structure:
One of the alternatives discussed by Sungcheol is a "DC specific frame structure including dedicated resource usage (Zone)"
I would like to ask the Sungcheol and the rest of the forum what is the meaning of this alternative, specifically:
1) Are 2 HR-MS in the same cell allowed to transmit on the same resources (assuming that they are far enough)?
2) Is the HR-BS allowed to re-use the same resources for its own DL transmissions or the UL transmissions of one of its HR-MS (assuming that the HR-MS is close enough to the HR-BS)?
3) Are these resources fixed for all cells?
4) Can they change over time?
Thanks and Best Regards,
Eldad
Office +1 631 622 4134
Mobile +1 631 428 4052
Based in NY area
-----Original Message-----
From: Wang Haiguang [mailto:hwang@I2R.A-STAR.EDU.SG]
Sent: Wednesday, April 06, 2011 5:55 AM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: Re: [STDS-802-16] [802.16n][DC] Discussion on Usages and Frame Structure for DC
Hi, Sungcheol and all.
According the SRD, the system requirements for
direct communication (6.1.3.1) and HR-MS forwarding
(6.1.3.2) are defined in two separate sub-sections.
I think that we should define two separate sets of usages
for the direct communication and local forwarding as follows:
* Usages [EZ] Modes for HR-MS direct communication
- [EZ] Both HR-MSs are associated with an HR-BS infrastructure node.
- HR-MSs does not associate to HR-BS.[EZ] Infrastructure nodes are absent.
* Usages [EZ] Modes for HR-MS local forwarding
- One HR-MSs [EZ]is associated [EZ] with HR-BS infrastructure node and another one [EZ] one or more other HR-MSs are out of the coverage of HR-BS infrastructure nodes.
The direct communication and local forwarding should
be designed to support various applications, including
both data, video and voice since the SRD does not
make any constraint on the supported application.
Regards.
Haiguang
-----Original Message-----
From: Sungcheol Chang [mailto:scchang@etri.re.kr]
Sent: Wed 4/6/2011 8:48 AM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: [STDS-802-16] [802.16n][DC] Discussion on Usages and Frame Structure for DC
Dear 16n participants,
This is a kick-off mail for e-mail discussion on Usages and Frame Structure for direct communication
I suggest discussion guidelines as the followings:
- The subject of all the e-mails begins with the tag "[STDS-802-16] [802.16n][DC]" because DC RG has one e-mail discussion group now.
- Reply mails are expected to be within 24 hours because participants have different time zones.
- Any participants can add technical discussion issues for DC usage scenarios ad DC frame structure only.
[STDS-802-16] [802.16n][DC][Usage] Discussion on Usage Scenarios
There are three scenarios of direct communication (Let's focus on two HR-MSs at first)
1) Two HR-MSs under HR-BS coverage
2) One HR-MS under HR-BS coverage and The other HR-MS out of HR-BS coverage. (HR-MS forwarding)
3) Two HR-MSs in absent of HR-BS
[STDS-802-16] [802.16n][DC][Frame] Discussion on Frame Structure
Two cases of frame structure for direct communication
1) 16 frame structure including infrastructure frame structure and relay frame structure.
2) DC specific frame structure including dedicated resource usage (Zone)
Two cases of DC resource separation within 16 frame structure
1) TDM separation (Wideband approach)
2) FDM separation (Narrowband approach)
Note) Base on this kick-off e-mail, 16n participants concerning direct communication are encouraged to join this e-mail discussion actively.
Note) If participants want, participants can trigger e-mail discussion on other topic freely. Please use the other tag! (DC RG is not authorized to manage e-mail discussion among participants from 16n TG)
Best regards,
Sungcheol Chang