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Dear Hai-Guang, Eledad, Sungcheol, and all, Thank you very much for discussion. I have several questions: question 4 and 5. Hai-Guang, I am not clear about multi-hop in forwarding to network and numbers of HR-MS supported in Forwarding to network, could you please see my comments/question and make me more clear. Thank you a lot. Best regards, Mingtuo From: Zeira, Eldad [mailto:Eldad.Zeira@INTERDIGITAL.COM] Hi Sungcheol, please see my opinion on your comment to question 3 below. Thanks, Eldad Office +1 631 622 4134 Mobile +1 631 428 4052 Based in NY area From: Chang, Sungcheol [mailto:scchang@etri.re.kr] Hi all, Please see my comments to question 3. Best regards, Sungcheol Chang, Ph.D. Mobile Access Technology Research Team, ETRI From: Zeira, Eldad [mailto:Eldad.Zeira@INTERDIGITAL.COM] Hi Mingtuo, Haiguang Thanks for this discussion. I mostly agree with Haiguang's opinion but have one question for clarification and several suggestions. Eldad Office +1 631 622 4134 Mobile +1 631 428 4052 Based in NY area -----Original Message----- Dear Ming-Tuo and all, Thanks very much to Ming-Tuo bring this topic to the group. It is very important to have a common understanding these issues. I try to reply the questions based on my understanding. Please see my answer inline. Regards. Haiguang -----Original Message----- From: Ming-Tuo ZHOU [mailto:mingtuo@nict.com.sg] Sent: Thu 4/21/2011 6:20 PM To: STDS-802-16@LISTSERV.IEEE.ORG Subject: [STDS-802-16] [802.16n][DC] Discussion on definition of HR-MS DC and Forwarding to Network Dear 16n participants, I'd like to trigger discussion of definition of HR-MS direct communication and HR-MS forwarding to network, since from many discussions it seems there are some confusion regarding them. In my opinion, it is necessary to have a clear common understanding of these two functions for development of technical details in a more smooth way. Anyone is welcome to bring his/her understanding of these two functions by replying this email. I hope after several rounds of email discussion, we can achieve some consensus regarding these two functions. The discussion may be started by answering follow questions: 1. what is HR-MS direct communication (DC)? Haiguang: HR-MS direct communication means, the two HR-MSs involved in the communication are the producer and consumer of the data packets. That is, the source HR-MS pass the data packet down from upper layer to MAC and the destination HR-MS pass the packet to upper layer from MAC after receiving from the air. Clarification: the producer and consumer here are from the view of MAC. It does not mean the packet is originated from the source HR-MS and terminated at the destination HR-MS. Eldad: suggest the following text (editorial cleanup, I think it means the same) The two HR-MS that are in direct communications with each other are the source and the sink of data. Packets are passed from upper layers to MAC at the source and back to upper layers at the sink HR-MS. 2. what is HR-MS forwarding to network (FTN)? Haiguang: HR-MS forwarding means the forwarding HR-MS either forwards the data packet to HR-BS or to the HR-MSs that access the network via the forwarding HR-MS. The forwarded packet will not be passed to upper layer. Instead, it is forwarded to next hop at MAC layer. Eldad: again I agree with the principle and suggest the following wording: An HR-MS that forwards data to infrastructure node or to another forwarding HR-MS that is attached to an infrastructure node (if multi-hop is supported) does so without passing any data to or from higher layers. Ming-Tuo: Haiguang (and all), do you think multi-hop HR-MS forwarding is allowed supported in 16n? 3. what's difference between HR-MS DC, HR-MS FTN, and HR relay/local forwarding? Haiguang: The differences are: * For HR-MS DC, at the source HR-MS, the data packets are from upper layer and are passed to upper layer protocol at the destination HR-MS. * For HR-MS FTN, the data packet is forwarded to next hop at MAC layer. The data packets are not handled by upper layer protocol. HR-MS who forwards data packet is still an HR-MS. It only has a very simple relay function and can only support very few nodes, one or two. >From other HR-MSs' view, HR-MS performing the relay function is still an HR-MS. HR relay is a kind of infrastructure station designed for the purpose of relay. It is complex and like a BS. It is designed to support many MS in network access. * Local forwarding means the infrastructure station between MS and BS forwards data packets from downstream HR-station to destination HR-MS without passing it to upstream infrastructure stations. A general case is a HR-RS forwards the data packets from one of its HR-MS (source) to another HR-MS which is the destination. Eldad: - Not sure what is the meaning of "From other HR-MSs' view, HR-MS performing the relay function is still an HR-MS." - could you please clarify? - >From the SRD, an HR-RS is " A relay that complies with the requirements for relays in this amendment". This is an amendment to 802.16n or 2009, which means that an HR-RS is an RS or ARS as amended by 802.16n. I don’t think we need to define it any further, although we'll need to specify how to implement the requirements we have agreed to in the SRD. Haiguang: My meaning is that the HR-MS should aware that the MS forwards data control for it is an HR-MS. It is not a relay station. Sungcheol Chang: From the discussions and the definitions in the 16n SRD, the definitions of direct communication and HR-MS forwarding are clearly different in respect of data flow. But I still confuse that the technical difference between HR-MS forwarding and HR-RS functionalities. Even though HR-RS is an infrastructure node and HR-MS is a user terminal in nature, I think their names are not important. If devices should receive packets transmitted by HR-MS, a receiving function within devices is to receive the packets. Whatever the devices are called like HR-MS or HR-RS. Their receiving functionalities are similar in nature. I want to know what the technical differences are because we are in developing the AWD text proposal. What happen if we replace 1) HR-MS with HR-RS 2) forwarding HR-MS with HR-RS in the following definition? The definition of forwarding: "An HR-MS that forwards data to infrastructure node or to another forwarding HR-MS that is attached to an infrastructure node (if multi-hop is supported) does so without passing any data to or from higher layers." What happen if we assume a forwarding HR-MS as a HR-RS serving one sub-ordinate HR-MS only? Under this assumption, please list the technical difference between a forwarding HR-MS and a HR-RS serving one sub-ordinate HR-MS only. Personally, if we achieve a forwarding HR-MS functionality with simple modification of HR-RS including signaling procedures, I prefer the modification rather than defining new function and transmission schemes Also I’d like to know what forwarding HR-MS is more simple than HR-RS. I understand that HR-RS has more functionalities than HR-BS and HR-RS is a infrastructure node. There are two views about complexity. The one is hardware complexity because HR-RS is designed to serve multiple HR-MS. This complexity is not important issue in respect of functionalities. The other is functional complexity. HR-RS support two interfaces for relay operation: 1) interface between HR-BS and HR-RS, 2) interface between HR-MS and HR-RS. It’s clear that forwarding HR-MS has two interfaces also. The relay specification describes relay function in HR-RS, which is required to relay data and packets to HR-BS or HR-MS. Even though more than HR-BS functionalities, the HR-RS functionalities are selected ones required for relay operation. From this understanding, please list what forwarding HR-MS is more simple than HR-RS. It will help me to understand what the forwarding function is. [Eldad] the SRD states clearly that forwarding is a functionality of the HR-MS not the HR-RS (see excerpt below). Obviously there will be similarities between the forwarding function and a relay function as both support 2 interfaces. That doesn’t mean that the two are the same. The amount of similarity will be determined by technical contributions. For example only, frame structure can resemble relays (i.e. transmission in both UL and DL zones) or be in UL only (as some proposed). 6.1.3.2 HR-MS forwarding to networkHR-MS forwarding is defined as the case where the origination and termination of data are at the HR-MS and network respectively and vice versa. HR-Network shall support HR-MS forwarding of user data and control signaling between HR-MS and HR-BS and between HR-MS and HR-RS. The control signaling and data transmission for the HR-MS to HR-MS direct link shall at least be capable of operating within the frequency band that the HR-BS operates. An association establishment shall be supported. Ming-Tuo: Haiguang, I am not so clear bout “It only has a very simple relay function and can only support very few nodes, one or two.” -- you mean in Forwarding to Network, the a data packet can only be forwarded to only one or two HR-MSs? Eldad, Sungcheol and all, what’s your opinion? (Ming-Tuo) 4. Is HR-MS forwarding to network is allowed in case that both HR-MS and the forwarding HR-MS are out of coverage of any HR infrastructure station? (Ming-Tuo) 5. In “Forwarding to network”, what the meaning of “Network” ? if there is no backbone connect, is the “Network” there? Finally, the following is expected to be made: [Consensus: ] Thank you very much. Best regards, Ming-Tuo Zhou 16n DC RG co-chair |