These are exciting times for the world's first wireless mobile broadband internet technology - Mobile WiMAX is rapidly gaining world-wide adoption with corresponding commercial rollouts: In recent news, Imagine acquires Clear's Ireland operations, Reliance Infotel ltd. changes their mind and plans for Mobile WiMAX deployments in India, Clear plans several new markets inside the U.S. by the end of the year (with current standing of 21 states (50 cities)), Best Buy Connect in conjunction with Clear announces their official wholesale relationship to sell 4G Broadband Service in the U.S., and the WiMAX Forum announces WiMAX 16e Enhanced for further network optimizations. Moreover, the ITU ratified IEEE 802.16m is set to continue to advance this open-standard 4G Mobile Broadband Internet technology growth for the next several years to come.
In order to take advantage of the current proliferation of WiMAX - ready PCs (netbooks, notebooks) available online and in the retail channels, as well as be ready to intercept the near term launch of a variety of WiMAX-ready slate tablets and smartphones, a green field WiMAX operator needs to diligently perform early technology assessment between a whole host of these WiMAX enabled retail PCs, dongles, and CPEs within their own Mobile WiMAX network infrastructure (BS, ASN, CSN, etc.). Once the WiMAX Forum PKI (Public Key Infrastructure) requirements for the AAA (Authentication, Authorization, Accounting) server are satisfied, the green field operator can begin a first pass over-the-air network entry verification with subsequent DL/UL (downlink/uplink) speed testing. This first level assessment should bring a baseline confidence to the operator prior to a full-scale IOT (inter-operability) testing/optimization of the green field WiMAX network.
Let us do a quick review of a typical WiMAX network architecture: Essentially, the MS (member station)/SS (subscriber station) is on one side, and the BS (base station), ASN (Access Service Network) Gateway, CSN (Connectivity Service Network: HA(home agent), AAA, etc.) is on the other side. Please remember the following common interface terminologies: the air-interface between the MS to BS is termed R1, the interface between MS to CSN is R2, BS to ASN is R6, ASN to CSN is R3, ASN to another ASN is R4 and CSN to another operator's CSN is R5. Next, we provide a simplistic summary of the network entry and initialization process: Phase a) the MS scans the DL channel and synchronizes with the BS, Phase b) transmit parameters are obtained, Phase c) ranging is performed, Phase d) basic capabilities are negotiated, Phase e) MS authorized and public keys exchanged, Phase f) MS registration performed, Phase g) IP connectivity established, Phase h) time of day established, Phase i) operational parameters transferred, and Phase j) connections setup. Now, if you recall our aforementioned interface terminologies (R1, R3, R6, etc.), Phase a) through Phase d) can be categorized into the R1 interface, and Phase e) through Phase j) can be categorized into the R3 and R6 interfaces. Our focus for a first pass network entry assessment is mainly on the R1, R3 and R6 interfaces. From an OSI (Open System Interconnection) model perspective, our focus is on layer 1 (physical layer), layer 2 (data link layer), and layer 3 (the network layer). There are several commercially available network monitoring tools which are specifically designed for 1) functional verification (protocol monitoring along R1, R6 and R3, etc.), 2) performance verification (MAC layer of BS when connected to more than one MS, ASN-GW under loaded conditions, etc.), and 3) live network testing. In a green field deployment, these tools can quickly and effectively identify the root-cause of problems in the initial setup of the BS/ASN/CSN (AAA, etc.). Once basic network entry is made and an IP address is obtained by the MS, a quick speed test can be performed. To gain an accurate measurement of the DL/UL speed between MS and BS, it is advisable to build an independent performance server using a notebook PC (e.g. containing Speedtest APs) and place the PC server at the CSN.
Some well known network monitoring tools include Wireless Logix Group's XCAL Tool (this is installed on the MS (embedded WiMAX PCI Express Mini Card, WiMAX USB dongle, etc.) and provides the operator an accurate view of the RF performance (CINR, RSSI, etc.) from the client device point of view), Sanjole Corporation's Wavejudge 4800/4900 (over-the- air R1 monitoring and much much more, etc.), Tektronix Communication's NSA - network and service analyzer (R1, R3, R6 monitoring, etc. while placed onto a BS port), and open-source Wireshark network protocol analyzer (which mainly looks at the transport layer, etc.). The operator can also monitor the WiMAX conversation by observing back-end session logs at the CSN. In any case, the fundamental handshake between client (MS/SS) and network (WiMAX BS) must be proven out, and once this is achieved, the green field operator can advance to the next level of exhaustive IOT testing.
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