Cellular Networks No. 1  Seattle Pacific University Cellular Wireless Networks Common issues for wireless solutions Kevin Bolding Electrical Engineering Seattle Pacific University

Cellular Networks No. 2  Seattle Pacific University Wireless Systems H Base Network Handsets – Portable mobile devicesBase Station - Receiver Network connects base stations

Cellular Networks No. 3  Seattle Pacific University Wireless (Voice) System Design Goals 1. Transmit the voice signal without errors 2. Minimize the handset power 3. Minimize the handset cost 4. Maximize the handset/base station ratio 5. Stay within the allocated band/power 1 st Generation: Analog (AMPS) 2 nd Generation: Digital (GSM, CDMA) 3 rd Generation: Data Services (WCDMA, CDMA2000) 4 th Generation: Higher Speed data (OFDM, MIMO)

Cellular Networks No. 4  Seattle Pacific University Global Wireless Market Source: Wireless Intelligence,

Cellular Networks No. 5  Seattle Pacific University First Generation Mobile Phones Analog, using FM channels Voice only Easy to intercept

Cellular Networks No. 6  Seattle Pacific University Second Generation Mobile Phones GSM – Global System for Mobile Communications Open international standard 213 countries 2-3 billion subscribers (70% of market) All of Europe, much of Asia, much of Americas Uses digital TDM / WDM Voice + Text; 2.5G GPRS added data CDMA – Standard owned by QualComm Mostly replaced by GSM and 3 rd gen standards Was largest in North America and Asia Uses digital CDMA

Cellular Networks No. 7  Seattle Pacific University Third Generation Mobile Phones UMTS – Universal Mobile Telecomm System 3G version of GSM Wideband CMDA; TDMA variants also 300 Kbps – 2Mbps CDMA2000 – Upgrade to IS-95 CDMA 300 Kbps – 2Mbps Losing ground

Cellular Networks No. 8  Seattle Pacific University Fourth Generation Mobile Phones Official standard states 100Mbps mobile and 1Gbps stationary; No current “4G” systems meet that 4G and “4G” systems primarily use Orthogonal Frequency Division Multiplexing (OFDM) 3GPP LTE – 3 rd Generation Partnership Project Long- Term Evolution – 100Mbps maximum LTE Advanced – True 4G; in trials ( Mbps) WiMAX (IEEE e) – 128Mbps max WiMAX-Advanced (IEEE m) – Under development

Cellular Networks No. 9  Seattle Pacific University Generic Cellular System H Base H H H H H H H H H H H H H H H H H H H Base Station Controller Mobile Switching Center PSTN

Cellular Networks No. 10  Seattle Pacific University Cells Cannot reuse frequencies in six surrounding cells Hexagonally tiled cells Minimum of seven frequency sets required Repeat tiling of seven-cell array Distance between like cells must be far enough to avoid interference Smaller cells lead to better frequency reuse More calls per unit area Transmitted power must be smaller to avoid interference Requires careful power management Requires larger number of base stations

Cellular Networks No. 11  Seattle Pacific University Basic Issues for Mobile Communications H Base How do we manage multiple handsets communicating with one base? HHHH Base H How do we manage handsets entering and leaving communication? Base H How do we manage handsets moving from base station to base station? Base

Cellular Networks No. 12  Seattle Pacific University Basic Issues for Mobile Communications How do we manage multiple handsets communicating with one base? H Base H H H H Multiplexing (sharing the channel) Analog - Frequency-division Digital - Frequency-division and Time-division (GSM) Code-division (CDMA) We need at least: 1 send channel for each mobile 1 receive channel for each mobile 1 control channel

Cellular Networks No. 13  Seattle Pacific University Basic Issues for Mobile Communications Base H How do we manage handsets entering and leaving communication? To initiate a call Mobile issues request on paging channel Receiving towers “discuss” who will answer To receive a call System must know where the mobile is Idle mobile periodically broadcasts on paging channel System broadcasts page signal on paging channel for all bases near mobile

Cellular Networks No. 14  Seattle Pacific University Basic Issues for Mobile Communications Base H How do we manage handsets moving from base station to base station? Base Mobile uses idle slots to monitor control channels of nearby bases Keeps sorted list of the most powerful ones If error rate increases, mobile can either Increase power on same channel, same base Switch to a new base Handoff from base to base managed at higher level May be a soft handoff