Xizmat doirasi
Ikkala texnologiya uchun ham amaliy cheklov optik aloqa uchun byudjet qoidalariga bog'liq. Ikki tarmoq uchun belgilangan diapazon taxminan 20 km ni tashkil qiladi, optik ajratgichlarning bo'linish tezligidagi farq va har bir OLT tomonidan qo'llab-quvvatlanadigan optik tarmoq birliklari (ONU) soni ikkala tarmoq uchun farq qiluvchi ikkita omildir. texnologiyalar [10]. GPON 128 ONUgacha qo'llab-quvvatlashni taklif qiladi. EPON standarti bilan, lazer turiga qarab, texnologiya odatda har bir OLT uchun 32 tagacha foydalanuvchini yoki ba'zi hollarda Mavjud Xatoni Tuzatish (FEC) protokollaridan foydalangan holda 64 foydalanuvchini sig'dira oladi.
3.3. Tizim boshqaruvi
EPON oddiy tizim boshqaruvini talab qiladi, GPON esa uchta Layer 2 tarmoq protokollari uchun tizimlarni talab qiladi. Bu omil tarmoqdagi EPON uchun arzonroq narxni bildiradi. Bundan tashqari, EPON bir nechta protokollarni konvertatsiya qilishni talab qilmaydi, bu tarmoqdagi xarajatlarni kamaytirishning yana bir omiliga aylanadi.
3.4. Xavfsizlik
AES shifrlash (Advanced Encryption Standard) ITU-T GPON standartining bir qismidir. EPON tarmoqlarida shifrlash mexanizmi standartda aniqlanmagan. EPON-ning ba'zi sotuvchilari ham AES-dan foydalanadilar, EPON uzatishning har ikki yo'nalishida shifrlash jarayonini amalga oshiradi; yuqoriga va quyi oqimga. OAM xizmati (operatsiya, Ma'muriyat va texnik xizmat ko'rsatish) ikkita texnologiyada ham mavjud. GPON PLOAM+OMCI (Jismoniy qatlam operatsiyalari, ma'muriyat va texnik xizmat ko'rsatish + Ochiq boshqaruv mijoz asboblari) dan foydalanadi. EPON Ethernet OAM dan foydalanadi.
3.5. Number of Users per PON
The IEEE 802.3ah EPON supports only two types of ODN: type A (5dB to 20dB loss) and type B (10dB to 25dB loss), offering up to 32 users [ 8], while the standard GPON also supports ODN type C (15dB to 30dB loss). The ODN C PON allows the addition of extended 20km taking up to 64 ONTs. Using EPON networks enables the sellers to eliminate complex and expensive networks of ATM and SONET, reducing costs in the network.
3.6. Scalability and Flexibility
EPON supports only a symmetrical bit rate, 1.25 Gbit/s. GPON standard is more scalable and flexible, GPON enables downstream (dns) rates of 1.25 Gbit/s until 2.5 Gbit/s and upstream (ups) rates of 155 Mbit/s until 2.5 Gbit/s. The two platforms are focused on the market of optical access networks, where the clients traffic tends to be mostly asymmetric (dns>ups), and an ups rate of 1.25 Gbit/s tends to be excessive for every customer (only a few would effectively use it, and such high ups rate would increase the overall cost of the PON). Because of this, GPON allows the telecommunications services provider to set fees according to needs of the users, a mechanism that cannot be accomplished in EPON networks [11].
3.5. PON boshiga foydalanuvchilar soni
IEEE 802.3ah EPON faqat ikkita ODN turini qo'llab-quvvatlaydi: A turi (5dB dan 20dB gacha yo'qotish) va B turi (10dB dan 25dB gacha yo'qotish), 32 tagacha foydalanuvchi taklif qiladi [8], standart GPON esa C turini (15dB) qo'llab-quvvatlaydi. 30 dB gacha yo'qotish). ODN C PON 64 ONTgacha cho'zilgan 20 km masofani qo'shish imkonini beradi. EPON tarmoqlaridan foydalanish sotuvchilarga ATM va SONET ning murakkab va qimmat tarmoqlarini yo'q qilish imkonini beradi, bu esa tarmoqdagi xarajatlarni kamaytiradi.
3.6. Masshtablilik va moslashuvchanlik
EPON faqat nosimmetrik bit tezligini qo'llab-quvvatlaydi, 1,25 Gbit/s. GPON standarti yanada kengaytiriladigan va moslashuvchan, GPON quyi oqim (dns) tezligini 1,25 Gbit/s dan 2,5 Gbit/s gacha va yuqori (yuqoriga) 155 Mbit/s dan 2,5 Gbit/s gacha tezlikni beradi. Ikkala platforma optik kirish tarmoqlari bozoriga qaratilgan bo'lib, u erda mijozlar trafigi asosan assimetrik (dns>ups) bo'ladi va 1,25 Gbit/s ga ko'tarilish tezligi har bir mijoz uchun haddan tashqari ko'p bo'ladi (faqat bir nechtasi samarali bo'ladi). undan foydalaning va bunday yuqori o'sish tezligi PONning umumiy narxini oshiradi). Shu sababli, GPON telekommunikatsiya xizmatlari provayderiga foydalanuvchilarning ehtiyojlariga qarab to'lovlarni belgilash imkonini beradi, bu mexanizm EPON tarmoqlarida amalga oshirilmaydi [11].
3.7. Efficiency of the Standards
Both technologies use a fixed frame header added to transmit data to the user in the form of a packet. In EPON networks the information is sent in packets of varying lengths up to 1500 Bytes as IEEE 802.3 Ethernet standard. In GPON 53 bytes (5 bytes of header), as specified by the ATM networks the information is sent in fixed cells of protocol.
3.7. Standartlarning samaradorligi
Ikkala texnologiya ham foydalanuvchiga ma'lumotlarni paket shaklida uzatish uchun qo'shilgan qattiq ramka sarlavhasidan foydalanadi. EPON tarmoqlarida ma'lumotlar IEEE 802.3 Ethernet standarti sifatida 1500 baytgacha bo'lgan turli uzunlikdagi paketlarda yuboriladi. GPON-da 53 bayt (5 bayt sarlavha), ATM tarmoqlarida ko'rsatilgandek, ma'lumotlar protokolning qattiq kataklarida yuboriladi.
4. PLANNING A GPON/EPON NETWORK
In our study we plan a network to support the demand of 100000 users, with transmission bit-rates of 10 Mbit/s to 100 Mbit/s. For the scenario proposed we assume the following characteristics:
The efficiency of the GPON network will be established in 93%, while EPON will be 70%, implying that GPON will use a 2333 Mbit/s versus 896 Mbit/s of EPON. For simplicity the kind of the service offered will not be considered, only the demand for bandwidth per user. The split-ratio is due to splitters for GPON and EPON; we will use 1:32 for both platforms. The price for OLTs is the same for the two networks, US$ 2000 while for the ONTs we assume US$250 for GPON and US$200 for EPON (the price of the ONTs is not the same because GPON supports TDM services, POTS, E1 / T1, providing an extra feature compared to EPON). For ease of our analysis, we will consider that the cost of wiring and installation will be the same for both technologies, then, will be neglected in our study.
We found in our study that the number of OLTs for EPON networks tends to be larger than those required for GPON networks, becoming a visible economic benefit for the latter. Figure 1 and Figure 2 represent the number of ONTs to gauge our scenario of 100000 subscribers. Figure 3 and Figure 4 represent the number of OLTs.
4. GPON/EPON TARMOQINI REJALATISH
Tadqiqotimizda biz 10 Mbit/s dan 100 Mbit/s gacha uzatish tezligi bilan 100000 foydalanuvchi talabini qo'llab-quvvatlaydigan tarmoqni rejalashtirmoqdamiz. Taklif etilgan stsenariy uchun biz quyidagi xususiyatlarni qabul qilamiz:
GPON tarmog'ining samaradorligi 93% ga o'rnatiladi, EPON esa 70% bo'ladi, bu GPON 896 Mbit/s EPONga nisbatan 2333 Mbit/s dan foydalanishini bildiradi. Oddiylik uchun taqdim etilayotgan xizmat turi hisobga olinmaydi, faqat har bir foydalanuvchi uchun tarmoqni o’tkazish qobiliyati talabi hisobga olinmaydi. Split-nisbati GPON va EPON uchun ajratgichlar tufayli; ikkala platforma uchun 1:32 dan foydalanamiz. OLT narxi ikkita tarmoq uchun bir xil, 2000 AQSh dollari, ONT uchun esa biz GPON uchun 250 AQSh dollari va EPON uchun 200 AQSh dollarini taxmin qilamiz (ONT narxi bir xil emas, chunki GPON TDM xizmatlarini qo'llab-quvvatlaydi, POTS, E1 / T1, EPON bilan solishtirganda qo'shimcha xususiyatni ta'minlaydi). Tahlil qilish qulayligi uchun biz simlarni o'rnatish va o'rnatish narxi ikkala texnologiya uchun bir xil bo'lishini ko'rib chiqamiz, keyin bizning tadqiqotimizda e'tibordan chetda qoladi.
Bizning tadqiqotimiz shuni aniqladiki, EPON tarmoqlari uchun OLTlar soni GPON tarmoqlari uchun talab qilinadiganidan ko'proq bo'lib, ikkinchisi uchun sezilarli iqtisodiy foyda keltiradi. 1-rasm va 2-rasm 100000 obunachi stsenariyimizni o'lchash uchun ONT sonini ko'rsatadi. 3-rasm va 4-rasm OLTlar sonini bildiradi.
Figure 1. Number of ONTs GPON per PON.
Figure 2. Number of EPON-ONTs per PON.
Figure 3. Number of GPON-OLTs for 100.000 users.
Figure 4. Number of EPON-OLTs for 100.000 users.
As the user demand for bandwidth increases, EPON resources are quickly exhausted, and extra equipment is required. Figure 5 shows the overall cost of the networks GPON/EPON based on the bandwidth required by subscribers.
O'tkazish qobiliyatiga foydalanuvchi talabi ortib borayotganligi sababli, EPON resurslari tezda tugaydi va qo'shimcha uskunalar talab qilinadi. 5-rasmda abonentlar talab qiladigan tarmoqni o’tkazish qobiliyatidan kelib chiqqan holda GPON/EPON tarmoqlarining umumiy narxi ko'rsatilgan. Figure 5. Overall costs of OLTs for 100.000 users
Knowing the economic advantage, which means having the least amount of OLTs in GPON networks, we can calculate the sensitivity of the cost of ONTs in GPON, based on money saved. It will be calculated based on the money saved by applying the value against the total number of ONTs in the network. Thus, for a total savings of US$ 16.3 millions due to fewer OLTs in GPON for users with a service of 100Mbit/s, it can be invest US$16.3 millions on 100000 GPON ONTs (100000 more users). Thus, the GPON ONT can cost US$163 in order to have the same total cost of EPON network (see figure 6). For user bandwidths below 25 Mbit/s, this cost would be essentially zero.
Iqtisodiy afzalliklarni, ya'ni GPON tarmoqlarida OLTlarning eng kam miqdoriga ega bo'lishni bilgan holda, biz tejalgan pulga asoslanib, GPON-dagi ONT narxining sezgirligini hisoblashimiz mumkin. U tarmoqdagi ONTlarning umumiy soniga nisbatan qiymatni qo'llash orqali tejalgan pul asosida hisoblab chiqiladi. Shunday qilib, 100Mbit/s xizmatiga ega foydalanuvchilar uchun GPON-da kamroq OLTlar hisobiga jami 16,3 million AQSh dollarini tejash uchun 100000 GPON ONT (ko'proq 100000 foydalanuvchi) uchun 16,3 million AQSh dollari sarmoya qilish mumkin. Shunday qilib, EPON tarmog'ining umumiy narxi bir xil bo'lishi uchun GPON ONT 163 AQSh dollarini tashkil qilishi mumkin (6-rasmga qarang). 25 Mbit/s dan past foydalanuvchi tarmoqni o’tkazish qobiliyati uchun bu xarajat deyarli nolga teng bo'ladi.
Figure 6. Cost sensitivity of GPON-ONTs compared with EPON.
The money saved appears due to the number of OLTs, in this way the cost sensitivity for an OLT in GPON becomes an important economical factor. The cost sensitivity of the OLTs in GPON it can be calculated using the difference between the GPON equipments, applying it to the numbers of OLTs in the GPON. Figure 7 shows the cost sensitivity of the GPON OLTs compared to EPON.
Tejalgan pul OLTlar soni tufayli paydo bo'ladi, shuning uchun GPON-da OLT uchun xarajatlar sezgirligi muhim iqtisodiy omilga aylanadi. GPON-dagi OLT-larning xarajat sezgirligi uni GPON-dagi OLT raqamlariga qo'llash orqali GPON uskunalari o'rtasidagi farq yordamida hisoblanishi mumkin. 7-rasmda GPON OLT-larining EPON-ga nisbatan xarajat sezgirligi ko'rsatilgan.
Figure 7. Cost sensitivity of GPON OLTs compared with EPON.
This simple analysis for an FTTP shows an advantage because of the cost of GPON networks versus the cost of EPON. This is interpreted as due to the higher split-ratio in GPON and to the higher rate of transmission and efficiency, than EPON networks, thus resulting in the reduction of GPON OLTs in more than a factor of 2 over the EPON networks. Even though not a part of this analysis, one should point out that this translates into savings in the cost of physical space required and also in reduced power required by the Central Office.
Based on the previous scenario it is therefore possible to achieve an improvement of two to three times the revenue for each PON, using technology GPON instead of using EPON. The network designer must consider the fact that systems need less trees PON using GPON, consequently, reducing significantly the operational costs for the network. Moreover, the increase of the flexibility can be introduced with GPON using optionally the long-range optical to increase the coverage to more areas of service, adding several ways to protect the reliability of the fiber network, allowing encryption to provide benefits that can simplify the network without the need for additional equipment.
7. CONCLUSIONS AND RECOMMENDATIONS
Considering all the factors previously shown in our study, we found that the infrastructure of the GPON network is more robust, has more capacity and has a slight advantage over the EPON network. How we can sees in the results, actually we could design a EPON network to offer rates until 40Mbit/s of downstream traffic and we would have a slight advantage in terms of costs over GPON, but if we want to offer rates up to 40Mbit/s is more profitable to develop a GPON network.
So that, based on our results, we suggest for the planning of a PON network the next tips:
If the economic resources are not large and the rates offered do not outweigh the 40Mbit/s per user, we develop an EPON network, taking in consideration that the network does not has the capacity and scalability that has the GPON networks.
If the rates offered are intending to be over 40Mbit/s, undoubtedly we recommend to use GPON networks, due to its robustness, its scalability, its ability to accept TDM services and for one of the most important factor, the lower relative cost for such transmission rates compared with EPON.
Currently the networks GPON have a clear economic and engineering margin of advantage over EPON networks, even though most of the traffic on the world networks is IP, ideal for Ethernet PON.
FTTP uchun ushbu oddiy tahlil EPON narxiga nisbatan GPON tarmoqlari narxining afzalliklarini ko'rsatadi. Bu EPON tarmoqlariga qaraganda GPON-da yuqori bo'linish nisbati va uzatish va samaradorlik tezligining yuqoriligi bilan izohlanadi, natijada GPON OLT-larining EPON tarmoqlarida 2 baravardan ko'proq qisqarishiga olib keladi. Ushbu tahlilning bir qismi bo'lmasa ham, shuni ta'kidlash kerakki, bu zarur bo'lgan jismoniy maydon narxini tejashga, shuningdek, Markaziy ofis tomonidan talab qilinadigan quvvatni kamaytirishga olib keladi.
Oldingi stsenariyga asoslanib, EPON o'rniga GPON texnologiyasidan foydalangan holda har bir PON uchun daromadni ikki-uch baravar oshirishga erishish mumkin. Tarmoq dizayneri tizimlar GPON-dan foydalangan holda PON daraxtlarini kamroq talab qilishini hisobga olishi kerak, bu esa tarmoqning operatsion xarajatlarini sezilarli darajada kamaytiradi. Bundan tashqari, moslashuvchanlikni oshirish GPON bilan ixtiyoriy ravishda xizmat ko'rsatishning ko'proq sohalarini qamrab olish uchun uzoq masofali optikadan foydalangan holda kiritilishi mumkin, tolali tarmoqning ishonchliligini himoya qilishning bir necha usullarini qo'shib, shifrlashni soddalashtiradigan afzalliklarni taqdim etish imkonini beradi. qo'shimcha uskunalarga ehtiyoj sezmasdan tarmoq.
7. XULOSA VA TAVSIYALAR
Bizning tadqiqotimizda ilgari ko'rsatilgan barcha omillarni hisobga olgan holda, biz GPON tarmog'ining infratuzilmasi yanada mustahkamroq, ko'proq sig'imga ega va EPON tarmog'iga nisbatan biroz ustunlikka ega ekanligini aniqladik. Natijalarni qanday ko'rishimiz mumkin, aslida biz EPON tarmog'ini 40 Mbit/s gacha bo'lgan quyi oqim trafigini taklif qilish uchun loyihalashimiz mumkin va biz GPON-ga nisbatan xarajatlar bo'yicha biroz ustunlikka ega bo'lar edik, lekin agar biz 40 Mbit/s gacha bo'lgan tariflarni taklif qilmoqchi bo'lsak. s GPON tarmog'ini rivojlantirish foydaliroq.
Shunday qilib, natijalarimizga asoslanib, biz PON tarmog'ini rejalashtirish uchun quyidagi maslahatlarni taklif qilamiz:
Agar iqtisodiy resurslar katta bo'lmasa va taklif qilingan tariflar har bir foydalanuvchi uchun 40 Mbit/s dan oshmasa, biz tarmoq GPON tarmoqlariga ega bo'lgan sig'im va miqyosga ega emasligini hisobga olib, EPON tarmog'ini ishlab chiqamiz.
Agar taklif qilinayotgan tariflar 40Mbit/s dan yuqori boʻlsa, biz shubhasiz GPON tarmoqlaridan foydalanishni tavsiya qilamiz, chunki uning mustahkamligi, miqyoslanishi, TDM xizmatlarini qabul qilish qobiliyati va eng muhim omillardan biri buning uchun nisbatan past narx hisoblanadi. EPON bilan solishtirganda uzatish tezligi.
Hozirgi vaqtda GPON tarmoqlari EPON tarmoqlariga nisbatan aniq iqtisodiy va muhandislik ustunliklariga ega, garchi jahon tarmoqlaridagi trafikning aksariyati Ethernet PON uchun ideal bo'lgan IP bo'lsa ham.
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