无线与频宽整合之多媒体通讯技术

工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线与频宽整合之多媒体通讯技术 周胜邻 博士 工研院电通所 网络技术组 组长 2003. 11. 26 2 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 课程目的 本课程将与您一起探讨通讯产业中三个重要之发展趋势 IP 电信 (VoIP)逐渐成为未来通讯技术之主流 , 不仅将对服务产业将发生变化 , 而且也将为通讯产品产业带来新契机 ；本课程将提供学员对此一领域做初步之介绍 ENUM为一项非常新的技术 , 它将是推动 IP/ PSTN系统与服务整合的最大动力 , 同时也将对因特网之应用产生革命性之冲击 , 为人们使用日常生活之所有通讯服务带来莫大之便利 ； 本课程将对此一最新技术及其发展趋势做深入浅出之说明 WLAN 之近年来成为无线通讯之热门话题 , 各企业甚至家庭开始积极建设 WLAN, 此趋势相信将持续几年 . 不过建设 WLAN作何用途 ? Public WLAN 服务业者有无生存空间 ? WLAN 与 3G关系又是如何 ? 互补呢还是竞争 ?本课程最后一节将与您一起探讨 WLAN 与无线通讯系统之竞合关系 , 了解 WLAN应用之发展趋势 3 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 课程大纲 IP 电信技术的发展趋势 VoIP 的过去现在与未来 VoIP 的技术发展 -从 H.323 到 SIP SIP 的应用与发展趋势 ENUM - IP/PSTN整合之新趋势 何谓 ENUM? ENUM 服务机制 WLAN 应用服务的发展趋势 WLAN 之应用 WLAN 与无线通讯系统之整合 4 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 通讯产业几个重要发展趋势 VoIP 产业复苏 , 有蓬勃发展趋势 IP-Phone, Wi-Fi SIP Phone, Residential Gateway, IP-PBX, 日本 Yahoo BB, J-Phone, Wireless LAN 蓬勃发展 , 但服务商业模式尚待开发 技术演进迅速 , 公司企业 , 家用 Public WLAN, Cellular/WLAN 整合 ? Wireless Data (Mobile Internet) 发展不如预期 Mobile Data Voice SMS, MMS, 3G 通讯系统前景不明 GPRS ? 3G ? Cdma2000-1x vs. WCDMA ? 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories IP 电信技术的发展趋势 6 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Yahoo!BB VoIP Business Model Over 1M+ BB Phone users (Dec 5th, 2002 Press Release) PSTN (NTT) DSLAM S Gateway Call Agent / Softswitch ISP / ASP (Yahoo!BB) VoIP TA VoIP TA On-net call free Off-net call 7.5 Yen/ 3 min. (1) Calls from PSTN (2) PSTN specific services, e.g. emergency call ASDL + VoIP as The First Mile POTS phones + PSTN phone numbers 7 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 VoIP 的过去 Born of VoIP Industry VoIP Phone - VocalTech 1995 H.323 Standard for VoIP Industry H.323 Was Proposed by ITU-T for Multimedia Communication over LAN in 1996 Adopted Quickly and Widely by Industries VoIP Gateway, Gatekeeper, Enterprise GW, IAD Mainly Used in Enterprise, Toll-by-Pass Applications Market Slow Down Infrastructure Bottleneck - Limitation of H.323 New Technologies Developed Users Hesitate to Buy H.323 Products Vendors Invest Much in H.323 8 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 VoIP 的现在 New Technologies Ready MGCP, MEGACO/H.248, SCTP/M3UA, SIP/SDP, IETF-like Protocols New Products Developed Most Upgraded from H.323 Products Support New Technologies as well as H.323 VoIP Infrastructure Softswitch, Trunk GW, SS7 Signaling GW (SS7 over IP) Market Re-Booming IETF Technologies Dominate SIP Telephony Being Widely Accepted ENUM for IP/PSTN Convergence Being Developed Softswitch vs. SIP Softswitch: Mainly for Class 4/5 Switch Replacement SIP: Provide Telephony from IPs Point of View 9 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 VoIP 的未来 VoIP Infrastructure will Get Ready (How Soon ?) ENUM for IP/PSTN Convergence Product and Service Start to Boom Its Technologies Trend, Not Just for Cost Saving Driving Force of NGN Mandatory in Future All-IP Network SIP Technologies Will Dominate SIP Telephony/CO Signaling/Multimedia Service/3G Key Technologies for IP/PSTN Convergence 10 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Trends of VoIP Technologies H.323 System Next Generation VoIP Protocols Open Telephony Architecture Internet Telecom Service Technologies MGCP MEGACO/H.248 SIP/SDP SS7 over IP (SCTP) 3GPP Open Service Arch. ISC Softswitch VoIP Call Modeling API: Parlay, JAIN,. IP-based SCP IP-SCE Pretty Amazing New Services (PANS) VoIP Technologies for 3G Core Network 97 98 99 00 01 02 03 04 05 06 Enterprise VoIP Systems Carrier-grade Internet Telecom. System 3G All-IP Core Network System Applications Technology Complexity VoIP Gateway/Gatekeeper IP-PBX IP-Phone Softswitch Signaling Gateway Media Server&Gateway(IAD, Trunk G/W) Application Server SIP-based Systems IP-SCP IP-SCE Year 11 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 IP/PSTN Convergence PSTN SIP Proxy ENUM Service System SIP Phone SIP Phone Gateway Softswitch Application Server Media Server SIP Telephony H.323 ENUM Servers Operator 1 Operator 2 SIP SIP DNS IP Network 12 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 VoIP Services Applications PSTNs (Telecomm.s) Point of View Equip PSTN with VoIP Services Original Voice Users For Cost Saving, No Service Enhancement Class 4/5 Switch Replacement with Softswitch No Extra Revenue ISPs (IPs) Point of View Enhance Data Network with VoIP Capability Additional Voice Service to Original Data Users Even Voice/Data Integrated Services SIP Telephony + Application/Media Servers 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories VoIP Technologies - From H.323 to SIP 14 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 H.323 for VoIP Has Been Adopted by Vendors for Years Almost Current VoIP Products Support H.323 Gateway Gatekeeper Terminal MCU Packet Based Network N-ISDN B-ISDN H.320 Terminal H.321 Terminal H.321 Terminal H.310 terminal operating in H.321 mode GSTN H.324 Terminal H.322 Terminal Guaranteed QoS LAN Speech Terminal Speech Terminal V.70 Terminal H.323 MCU H.323 Terminal H.323 Terminal H.323 Terminal H.323 Gatekeeper H.323 Gateway Packet Based Network 15 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Challenges of H.323 H.323 Was Originally Proposed for LAN Environment Limitation Being Applied for VoIP Infrastructure Applications Architecture is Too Simple Single Gateway to Interact with PSTN/GSM Suitable for Peer to Peer Communication Protocol is Too Complex Complicated Call Set-Up Signaling Hard to Extend Signaling Is Not Enough Only DTMF is Specified No SS7 Signaling Capability Advanced Services are Limited Interoperability is Still an Issue 16 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Gateway Decomposition SS7 Signaling Traffic Media GW (MG) Media GW Controller (MGC) Signaling GW (SG) H.323 GW MGC: Call Control, Call Routing, Service Selection, SG Interface with SS7 and Translate to SS7 over IP MG Dedicate for Media Translation and Transportation MGCP 17 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Media Gateway Control SGCP Telcordia May 98 MDCP AT&T Dec 98 Aug 00 MEGACO/H.248 IETF/ITU-T Level3,. Aug 98 IPDC 0.12 IPDC 1.0 Sept 98 MGCP 1.0 IPDC: IP Device Control Protocol SGCP: Simple Gateway Control Protocol MGCP: Media Gateway Control Protocol MDCP: Media Device Control Protocol MEGACO: Media GAteway Control (IETF Working Group) 18 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 MGCP/MEGACO/H.248 Client-Server Architecture Call Agent (Media Gateway Controller) Call Control Server Media Gateway Dedicated for Media Transmission Trunk/Access/Residential GWs Signal Gateway SS7 Interfacing RTP Streams SS7 (ISUP) SGW SGW SS7 (ISUP) Trunk GW Trunk GW CO IP phone Access GW/ IP-PBX/RGW IP phone MGCP MGC (CA) MGC (CA) MGCP/ MEGACO MGCP/ MEGACO 19 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 ISUP/MGCP/SIP Interworking Tele p h o n eTo SS7CA CAI AM C reat e C onnI nv it eCreate ConnAC KI AMAC MR ingingAC MAN M200 OKAC KAN MAC KTele p h o n eMGCPMGCPGatewayCACATo SS7GatewayIPAC KM odif y C onnGW GWSS7 SS7MG CP MG CPSIPRTP Aud ioSG MGC MGC SG 20 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SS7 over IP ISUP TCAP SCCP MAP MTP OSI Layers Application Presentation Session Transport Network Data Link Physical INAP SS7 Protocol Stack ISUP TCAP SCCP MAP SCN Signaling Adaptation (M3UA, IUA, ) Common Signaling Transport (SCTP) IP INAP SIGTRAN Protocol Stack 21 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Softswitch System Architecture IN/SCP PSTN Local Switch PSTN Local Switch STP SS7 Network IP Network RTP Streams MGC MGC Trunk Gateway Trunk Gateway SIP-T SG SG SIGTRAN Megaco IP Phone IP-PBX IP Phone PC Phone 9000 Personalized VoIP Service System Billing/Internet Messaging Authentication/Directory/. 22 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 What is A Softswitch ? Software, hardware and applications solutions typically come packaged in a single (proprietary) box. Non-standard solutions are expensive to implement and leave little room for innovation. Circuit-Switched Transport Hardware Call Control & Switching Services & Applications PROPRIETARY Solutions are open standards-based products, and can come from multiple vendors. Customers are free to choose best-in-class products to build their network. Open standards enable innovation and in the long run can reduce costs Soft-Switched Transport Hardware Softswitch Call Control Services, Applications & Features (Management, Provisioning and Back Office) Open Protocols APIs Open Protocols APIs 23 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Wireless System - From GSM to GPRS GPRS External Data Network PSTN HLR SGSN GGSN Gb Gn Gi GSM PCU BSS Gateway MSC/VLR Visited MSC/VLR Always-On Wireless Packet Data Services 24 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 IP Multimedia in 3G All-IP System Applications & Services SCP TE MGW MT UTRAN R Uu TE SGSN MT BSS/ GERAN R Um MGW PSTN Legacy/External GGSN HSS Legacy Mobile Signaling Network R-SGW CSCF HSS MGCF Gb Iu Iu Iu Iu A T-SGW EIR MSC Server GMSC Server Applications & Services CSCF Multimedia IP Networks MRF Gn Gf Gc Gr Gi Gi Gi Mr Ms Mg Mw Gi Mm Mc Mc Mc D C CAP CAP CAP Mh Cx Nc Nb Signaling and Data Interface Signaling Interface Alternative Access Network SIP 25 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Telephony System User Agent Client(Caller) User Agent Server(Callee) Proxy Server Proxy Server Proxy Server Redirect Server Location Server SIP Request SIP Response RTP Media Stream 26 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Attributes User Agents End Systems Acting on Behalf of a User Clients(UAC) to initiate a SIP request and servers(UAS) to receive the request and return responses Servers Proxy Server Relay Call Signaling Redirect Server Registrar Server: User Locations Tracking (Like HLR in GSM) Naming & Addressing SIP URL, e-mail like: userhost Examples sip: sip:Jackie 27 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Operation in Proxy Mode 28 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Operation in Redirect Mode 29 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Protocol Format INVITE sip:pgnexample.se SIP/2.0 Via: SIP/2.0/UDP From: Fingal To: Patric Call-ID: 1234567890 Cseq: 1 INVITE Subject: lunch at La Empenada? Content-Type: applcation/sdp Content-Length: v=0 o=ffl 53655765 2353687637 IN IP4 s=Chorizo c=IN IP4 m=audio 5004 RTP/AVP 0 3 5 a=rtpmap:0 PCMU/8000 SIP Header Payload: MIME type (SDP) 30 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP in IP Multimedia Architecture Applications SDP/SDPng HTTP SMTP SAP SIP RTSP TCP/SCTP TCP/UDP UDP RTP/ RTCP R S V P IPv4/IPv6 with Mobility, DiffServ and Multicast Common Addressing, userdomain (URI & URL) Text-based and Encoding Format Same Request-Response Model, and Response Codes MIME for Flexible Payload DNS for Address Mapping Easy to Do Integrated Services by Combining more than One Protocols 31 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP-Based Services Internet Telephony Well-Recognized IP Telephony System Instant Messaging Exchange of Content between Participants in Real-time Presence Subscription to and notification of changes in the comm. State of a users Click-to-Call from an Electronic Document SIP as tag Contained in Document Transport of MIME in SIP Signaling Reference to Web/WAP Pages, mail, pictures Interactive Games with SIP Signaling 32 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 Rich Call with SIP Before the Call Dynamic Phone Book Click-to-Talk During Call Establishment Sending a Rich Clip, which Can be A Picture with Call Subject, or Special Ringing Tone During the Call Document Sharing Information Push During Session Tear-Down (same as Call Establishment) After the Call Be Able to Send Instant Message 33 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP for Instant Messaging Integration of Messaging, Presence, and Session-oriented Communication RFC 3428 - SIP Extension for Instant Messaging SIP MESSAGE Method - Pager-mode IM For small IM Exchange Carry IM on Signaling Channel - Big Overhead Pager-mode vs. Session mode Instant Messaging Pager-mode - Each message is independent of any other message Session-mode - IMs are associated with a media session established by SIP INVITE method Message Session Relay Protocol (MSRP) - IETF Draft Support Session-mode IM between Endpoints 34 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP for IP Convergence In 3G and NGN, the Focus Shift towards to All-IP Paradigm IP Transport, IP Mobility and VoIP (e.g. SIP) Protocol SIP Has Been Adopted by 3GPP for Session Signaling SIP Telephony System Has Been Well Accepted With SIP, Service Creation is Fast and Easy IP Protocols vs. Telecom Protocol, like IN Be able to Integrate Most IP-based Services Service Mobility and Personal Reachability By SIP and IPv6 Mobility 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories CCL VoIP Solutions 36 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL VoIP Solutions Protocols H.323, SGCP, MGCP/H.248, SIP, RTP/RTCP, SCTP and M3UA, Related VoIP Products Technologies and Systems CTI / IP-PBX Softswitch / Media Gateway Controller SS7 over IP Signaling Gateway Trunk Gateway Media Server, Application Server SIP-based Presence/Messaging Server SIP-based IP Telephony SIP User Agent SIP Proxy Server SIP-based Application Server 37 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 IP-PBX LAN/WLAN IP Trunking Rich PBX features Internet Call Center ACD: Automatic Call Distribution 38 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL IP-PBX - VONTEL (cont.) Enterprise grade IP-PBX Rich Call Features Up to 5,000 devices BHCA: 60,000 (Busy Hour Call Attempt) Multimedia IP Call Center Solution Platform Advanced Skill-based Routing ACD System Rich 3-party Call Control API Support Voice / E-mail / Fax / and other media Provide both proprietary & TAPI 3.0 compatible APIs Converged Switch System PSTN Interworking (Megaco Interworking) SIP Interworking H.323 Interworking Inter-Switch Call Setup 39 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL IP-PBX - VONTEL (cont.) Media Server Voice Play / Record Fax Send / Receive DTMF Generation / Detection Advanced Multi-party Conference (up to 8 parties / wiretap / whisper) Softphone Full-Feature, Intelligent Softphone PSTN Gateway Support Analog FXO Interface Support T1/E1 ISDN Primary Rate Interface Web-based OA&M 40 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Telephony System IP Network PSTN SS7 Softswitch Trunk Gateway E1 Trunk SIP Phone (Cisco, PingTel) Web/Audio/Video Conferencing Application/Media Server (IP Unity) User Agent (Softphone) SIP Proxy Server On-net Call Off-net Call Unified Messaging Instant Messaging Presence 41 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL SIP Protocol and Achievements 7th SIPIT, March2001 March March 2001, sponsored by ETSI at Cannes, France CCL SIP Protocol Stack and User Agent 10th SIPIT, 2002 April April 2002 , sponsored by ETSI at Cannes, France CCL SIP Proxy Server 13th SIPIT, 2003 August August 20023 , sponsored by ETSI in Canada CCL SIMPLE Server 15th SIPIT, 2004 August ITRI will Host 15th SIPIT Sponsored by ETSI in Taiwan in August 2004 42 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL SIP User Agent CCL SIP Protocol Stack Provide C language API Support RFC 2543 headers Support RFC 2327 SDP Parsing Support TCP and UDP Support multi-platform (Windows, Solaris, Linux) CCL User Agent RFC 2543 and RFC 2543bis compliant Rich Call Feature Call Forwarding, Transfer, Hold, Consultation, Support RFC 2916 ENUM (E.164 number and DNS) Support Windows platform 43 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL SIP Proxy Server CCL SIP Proxy Server RFC 2543 and RFC 2543bis compliant Support Register Support Redirect Support location service Support stateful and stateless mode operation Support parallel and sequential search Support RFC 2916 ENUM (E.164 number and DNS) Support multi-platform (Windows, Solaris, Linux) 44 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 SIP Telephony Features Basic telephony features Basic on-net call Basic off-net call (PSTN interworking) Enhanced features Calling number delivery (CND) Call forwarding busy (CFB) Call forwarding dont answer (CFDA) Call waiting (CW) Selective call rejection (SCR) Auto recall Application/Media server functions Announcement Voice mail Conferencing 45 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories 无线宽带整合多媒体通讯技术 CCL Softswitch Solution Media Gateway Controller Signaling Gateway PSTN 10/100 Ethernet Switch Media Server Announcement Voice Mail Conferencing IP Network IP Router Application Server Web Conferencing Unified Messaging Billing Gateway Database Server Element Management Server SS7 Trunk Gateway Integrated Access Devices 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Research Laboratories ENUM - IP/PSTN整合之新趋势 47 工業技術研究院 電腦與通訊工業研究所 Industrial Technology Research Institute Computer & Communications Rese