SISTEM KOMUNIKASI BERGERAK

BAB 4KEMAJUAN DAN PERKEMBANGAN

SISTEM KOMUNIKASI SELULER

PENDAHULUAN

• 2 Jenis sistem komunikasi : Analog dan digital• Analog: AMPS (masih digunakan hingga sekarang)• Digital wireless network: Ada 2 tipe yaitu celluler

network pada prinsipnya untuk membawa panggilan suara tapi sudah berkembang menjadi membawa komunikasi data dan multimedia. Tipe kedua yaitu digital wireless network seperti lokal dan personal area network. Contohnya Wi-Fi dan Bluetooth.

GENERASI DALAM CELLULER KOMUNIKASI

• 1G : Analog celluler network, voice, 900 MHz, modulasi analog• 2G (circuit switching technology) : Digital celluler network

yaitu GSM, D-AMPS or IS -36 dan IS-95• 3G (Packet-switched mode)

Fourth Generation (4G)

• The 4G Mobile communications will be based on the Open Wireless Architecture (OWA) to ensure the single terminal can seamlessly and automatically connect to the local high-speed wireless access systems

• Based on this OWA model, 4G mobile will deliver the best business cases to the wireless and mobile industries, i.e.cdma2000/WLAN/GPRS 3-in-1 product, WCDMA/OFDM/WLAN 3-in-1 product, etc.

• by open wireless architecture system, various different wireless standards can be integrated and converged on this open platform.

• when the users are in the offices, homes, airports or shopping centers where the wireless access networks (i.e. Wireless LAN, Broadband Wireless Access, Wireless Local Loop, HomeRF, Wireless ATM, etc) are available. When the users move to the mobile zone (i.e. Highway, Beach, Remote area, etc.),the same terminal can automatically switch to the wireless mobile networks (i.e.GPRS,W-CDMA,cdma2000, TD-SCDMA, etc.).

Advantages

• 4G are high in terms of data rates, spectral efficiency, mobility and integration.

• Orthogonal Frequency Division Multiplexing (OFDM) is multiple access technology to be used in 4G.

• Multi-service platform• Low bit cost• Open wire less Architecture(OWA) • Multiple-input multiple-output ( MIMO )

Challenges

• Mobile Station1. To be able to use 4G mobile networks a new type

of mobile terminals must be conceived.2. The terminals must adapt to multiple wireless

networks, each with different protocols and technologies.

3. Auto reconfiguration , so that terminals can adapt to the different services available. It must download automatically configuration software from networks in range.

4. terminals must be able to choose from all the available wireless networks the one to use with a specific service.

5. It must be aware of specifications of all the networks in terms of bandwidth, QoS supported, costs and respect to user preferences.

6. Terminal mobility will be a key factor to the success of 4G networks. Terminals must be able to provide wireless services anytime, everywhere. This implies that roaming between different networks must be automatic and transparent to the user.

7. There are two major issues in terminal mobility, location management and handoff management.

• Location management deals with tracking user mobility, and handling information about original, current and (if possible) future cells. Moreover it must deal with authentication issues and QoS assurances.

• Handoff management primary objective is to maintain the communications while the terminal crosses wireless network boundaries.

• In addition, 4G networks, in opposition to the other mobile generations, must deal with vertical and horizontal handoffs, i.e., a 4G mobile client may move between different types of wireless networks (e.g. GSM and Wi-Fi) and between cells of the same wireless network (e.g. moving between adjacent GSM cells).

• Furthermore, many of the Services available in this new mobile generation like video conference have restrict time constraints and QoS needs that must not be perceptible affected by handoffs.

• Another major problem relates to security, since 4G pretends to join many different types of mobile technologies. As each standard has its own security scheme, the key to 4G systems is to be highly flexible.

• Service1. 4G users may have different operators to different

services and, even if they have the same operator, they can access data using different network technologies.

2. Actual billing using flat rates, time or cost per bit fares, may not be suitable to the new range of services. At the same time it is necessary that the bill is well understood by operator and client.

3. How the user can be contacted. This is very important to mobility management. A user must be able to be reached wherever he is, no matter the kind of terminal that is being used.

4. The most popular being the use of a mobile-agent infrastructure. In this framework, each user has a unique identifier served by personal mobile agents that make the link from users to Internet.

• Use multiple antennas at both base station and subscriber ends.

• Multiple antenna technologies enable high capacities suited for Internet and multimedia services and increase range and reliability.

• The target frequency band for this system is 2 to 5 GHz due to favorable propagation characteristics and low radio-frequency (RF) equipment cost.

• The broadband channel is typically non LOS channel and includes impairments such as time selective fading and frequency-selective fading.

• Multiple antennas at the transmitter and receiver provide diversity in a fading environment.