WiMAX
The first commercial OFDM-based WiMAX deployments based on the IEEE 802.16-2004 air interface standard occurred in 2006. Providing services for fixed, nomadic, or portable services, WiMAX quickly gained market acceptance as an alternative to broadband fixed wireline services. Since then the 802.16e-2005 amendment to the IEEE 802.16 air interface standard with the addition of OFDMA and other key features added mobility to the supported WiMAX usage models. Certified WiMAX products based on the 802.16e-2005 amendment have been commercially available since 2008. As of mid 2009 more than 130 products have received WiMAX certification and over 60% of these are Mobile WiMAX certified. There are now more than 500 WiMAX deployments currently underway serving a range of usage models from fixed to mobile services in more than 140 countries.
To further improve on the performance and features of WiMAX, the WiMAX Forum has completed and approved a portfolio of air interface enhancements [Ref 3]. Among the additional supported features are many air interface related enhancements that directly impact peak channel data rate and average channel and sector throughput. These are the metrics most often referenced in the discussion and comparison of different wireless access technologies and will be used in this paper to compare WiMAX with HSPA+ and LTE. A number of new frequency profiles and frequency division duplex (FDD) are also included with these enhancements. The new profiles address new spectrum allocations being made available by local regulators and FDD further expands the applicability of WiMAX into markets that have regulatory constraints on the use of TDD. FDD also gives operators added deployment flexibility where there are no such regulatory constraints and spectrum licenses are configured in paired channels.
To further improve on the performance and features of WiMAX, the WiMAX Forum has completed and approved a portfolio of air interface enhancements [Ref 3]. Among the additional supported features are many air interface related enhancements that directly impact peak channel data rate and average channel and sector throughput. These are the metrics most often referenced in the discussion and comparison of different wireless access technologies and will be used in this paper to compare WiMAX with HSPA+ and LTE. A number of new frequency profiles and frequency division duplex (FDD) are also included with these enhancements. The new profiles address new spectrum allocations being made available by local regulators and FDD further expands the applicability of WiMAX into markets that have regulatory constraints on the use of TDD. FDD also gives operators added deployment flexibility where there are no such regulatory constraints and spectrum licenses are configured in paired channels.
WiMAX Air Interface Release 1.5
The air interface enhancements approved for WiMAX, designated as WiMAX Air Interface Release 1.5 (aka Air Interface R1.5), are scheduled for certification testing readiness in 2010. A more detailed description can be found in reference 3. A summary of key PHY and MAC features or enhancements planned for Air Interface R1.5 are summarized in the following table:
The air interface enhancements approved for WiMAX, designated as WiMAX Air Interface Release 1.5 (aka Air Interface R1.5), are scheduled for certification testing readiness in 2010. A more detailed description can be found in reference 3. A summary of key PHY and MAC features or enhancements planned for Air Interface R1.5 are summarized in the following table:
| PHY/MAC Feature | Description |
| Duplex | Support for Frequency Division Duplex (FDD) and Half Duplex FDD for increased deployment flexibility when spectrum licenses comprise paired channels. |
| 20 MHz Channel BW | 20 MHz added as an optional channel BW in the 1710- 2170 MHz band. |
| AMC Permutation | Adjacent Multi-carrier (AMC) provides more efficient sub-carrier utilization compared to PUSC in low mobility situations translating to higher peak data rate and higher average channel throughput. |
| MIMO Enhancements | -DL open and closed loop MIMO with AMC permutation. -UL collaborative spatial multiplexing (SM) for two MSs in AMC mode. -UL open loop STC/SM MIMO in AMC and PUSC mode -Cyclic delay diversity |
| MAC Efficiency Enhancements | DL and UL Persistent Allocation of Information Elements (IE’s) for reduced MAP overhead with both persistent and non-persistent traffic. |
| Handover Enhancements | Improved efficiency with seamless handover |
| Load Balancing | -Load Balancing using preamble index and/or DL frequency override -Load Balancing using ranging abort timer -Load Balancing using BS initiated handover |
| Location Based Services (LBS) | -GPS-based LBS method -Assisted GPS (A-GPS) method -Non-GPS-based method |
| Enhanced Multicast & Broadcast Services (MBS) | Optimization/Clarification to MBS procedures such as group DSx and inter-MBS zone continuity messages |
| WiMAX-WiFi-Bluetooth Coexistence | -Co-located coexistence Mode 1 -Co-located coexistence Mode 2 -Combine UL band AMC with operation with co-located coexistence |
WiMAX Air Interface R1.5 also introduces several new TDD and FDD frequency profiles to address changing global spectrum allocations. Among the added profiles provided, coverage in the 698 to 862 MHz band is especially interesting in that it holds the promise of helping to bridge the digital divide in both developed and developing markets [Ref 4, 5]. Wireless access solutions in these lower frequency bands can provide a significant range and coverage advantage compared to allocations in the higher bands [Ref 6, 7]. As these lower bands become more widely available worldwide, the business case will be greatly enhanced for rural area deployments. Additionally, portions of these lower frequency bands are designated for public safety services, another important application well-suited to WiMAX. Profiles in the 1710 to 2170 MHz range, including the AWS (Advanced Wireless Services) band have also been added with Air Interface R1.5. This is one of the bands considered suitable for support of 20 MHz channel BW.
Peak Channel Rate Performance
The peak channel rate or peak user rate performance is a metric most often quoted in the comparison of varied access technologies. This is despite the fact that this data rate is only attainable in a limited portion of the cell coverage area where propagation conditions are sufficient to support the highest efficiency modulation scheme with minimal channel coding rate. Nevertheless, it is still an important metric for comparative purposes since it does reflect the best attainable channel performance and user experience. It is also directly proportional to the average channel throughput which, for deployment considerations, is a much more important performance metric.
Following table summarizes the parameter assumptions used for the peak channel rate performance for both Air Interface R1.0 and R1.5. Although (2x2) MIMO is also supported in the UL, (1x2) SIMO is assumed in this and following examples to represent a baseline mobile station (MS) configuration. In the UL, 16QAM is a mandatory feature with both Air Interface R1.0 and R1.5 whereas 64QAM is optional. In the table, 64QAM with 5/6 coding rate is assumed for both Air Interface R1.0 and R1.5. The modulation and coding rate difference alone provides a net increase of 66% in the UL data rate. The use of AMC vs. PUSC provides the additional improvement in UL peak data rate.
The results for the peak channel data rate are shown graphically in Figure 1. The projections for TDD assume a DL to UL ratio of 29:182 (approximately 3:2).
The results for the peak channel data rate are shown graphically in Figure 1. The projections for TDD assume a DL to UL ratio of 29:182 (approximately 3:2).
| | WiMAX | ||
| | Air Interface R1.0 | Air Interface R1.5 | |
| Duplex | TDD | TDD | FDD |
| Channel BW | 10 MHz | 10 MHz | 2 x 10 MHz & 2 x 20 MHz |
| Downlink | (2x2) SU-MIMO | (2x2) SU-MIMO | |
| Uplink | (1x2) SIMO | (1x2) SIMO | |
| Permutation | PUSC | AMC | |
| DL OH Symbols | 3 | 3 | 3 |
| DL Data Symbols | 26 | 26 | 45 |
| DL Modulation | 64QAM | 64QAM | |
| DL FEC Coding | 5/6 | 5/6 | |
| UL OH Symbols | 3 | 3 | |
| UL Data Symbols | 15 | 15 | 45 |
| UL Modulation | 64QAM | 64QAM | |
| UL FEC Coding | 5/6 | 5/6 | |
Average Channel Throughput Performance
Average channel or sector throughput performance provides a measure of the channel or sector capacity in a simulated multi-cellular deployment with multiple active users. Throughput performance is especially important in capacity-constrained deployments, typically encountered in high density urban environments. This parameter has a direct impact on the required base station to base station spacing necessary to satisfactorily meet peak busy hour capacity demands.
Evaluation Methodology
The evaluation methodology used for estimating throughput performance is similar to the methodology proposed by the NGMN Alliance [Ref 8] and the IEEE [Ref 9]. It is also consistent with the methodology being used for LTE Rel-8 simulations. The current methodology differs from the 1xEV-DV methodology [Ref 10] used in the past by 3GPP/3GPP2 .The following table summarizes the key parameters used for the most recent simulations3.
Evaluation Methodology
The evaluation methodology used for estimating throughput performance is similar to the methodology proposed by the NGMN Alliance [Ref 8] and the IEEE [Ref 9]. It is also consistent with the methodology being used for LTE Rel-8 simulations. The current methodology differs from the 1xEV-DV methodology [Ref 10] used in the past by 3GPP/3GPP2 .The following table summarizes the key parameters used for the most recent simulations3.
| Parameters | Values | |
| Number of Base Stations in Cluster | 19 | |
| Sectors per Base Station | 3 | |
| Operating Frequency | 2500 MHz | |
| Frequency Reuse | 1 | |
| Duplex | TDD | FDD |
| Channel Bandwidth | 10 & 20 MHz | 2 x 10 & 2 x20 MHz |
| BS-to-BS Distance | 0.5 kilometers | |
| Antenna Pattern | 70° (-3 dB) with 20 dB front-to-back ratio | |
| Base Station Antenna Height | 12 meters | |
| Mobile Terminal Height | 1.5 meters | |
| BS Antenna Gain | 15 dBi | |
| MS Antenna Gain | -1 dBi | |
| BS Maximum PA Power | 43 dBm | |
| Mobile Terminal Maximum PA Power | 23 dBm | |
| # of BS Tx/Rx Antenna | Tx: 2; Rx: 2 [(2x2) MIMO)] & Tx: 4, Rx: 2 [(4x2) MIMO] for Release 1.5 | |
| # of MS Tx/Rx Antenna | Tx: 1; Rx: 2 [(1x2) SIMO] | |
| BS Noise Figure | 4 dB | |
| MS Noise Figure | 7 dB | |
| Path Loss Model | I + 37.6 x Log(d) [d in km, I = 130.62 for 2500 MHz] | |
| Log-Normal Shadowing Std Dev | 8 dB | |
| BS Shadowing Correlation | 0.5 | |
| Penetration Loss | 20 dB | |
| Traffic | Full Buffer Data Traffic | |
| Number of Users | 30 per BS (10 per Sector) | |
| Mobility | SCM with 3 km per Hour | |
VoIP Capacity
WiMAX Air Interface R1.0 has a VoIP capacity of 30 simultaneous VoIP sessions per MHz per sector assuming an AMR 12.2 kps speech CODEC4. For the same duplex method and channel BW with persistent scheduling and the other planned enhancements, the VoIP capacity is increased by more than 40% with Air Interface R1.5. With TDD and (2x2) MIMO the net VoIP capacity for a 10 MHz channel BW is approximately 215 simultaneous sessions for Air Interface R1.5. This compares to 150 VoIP sessions for Air
Interface R1.0.
Interface R1.0.
LTE
Long Term Evolution (LTE) also referred to as Enhanced-UTRA (E-UTRA) was initiated in 2004 with the purpose of defining the next phase in the 3GPP migration path. The LTE specification requirements were initially defined in 3GPP Rel-8 with further enhancements provided in 3GPP Rel-9. With LTE, 3GPP transitions from CDMA in the DL to OFDMA. In the UL LTE employs Single-Carrier FDMA (SC-FDMA).
Some of the key performance goals initially established by 3GPP for LTE are:
Long Term Evolution (LTE) also referred to as Enhanced-UTRA (E-UTRA) was initiated in 2004 with the purpose of defining the next phase in the 3GPP migration path. The LTE specification requirements were initially defined in 3GPP Rel-8 with further enhancements provided in 3GPP Rel-9. With LTE, 3GPP transitions from CDMA in the DL to OFDMA. In the UL LTE employs Single-Carrier FDMA (SC-FDMA).
Some of the key performance goals initially established by 3GPP for LTE are:
- Peak DL Data Rate: 100 Mbps for 20 MHz channel BW and (2x2) MIMO BS, Peak DL efficiency of 5 bps/Hz.
- Peak UL Data Rate: 50 Mbps for a 20 MHz channel BW and (1x2) SIMO MS, Peak UL efficiency of 2.5 bps/Hz.
- Average DL Throughput: 3 to 4 times HSDPA (3GPP Rel-6) at pedestrian speed
- Average UL Throughput: 2 to 3 times HSUPA (3GPP Rel-6) at pedestrian speed
- Channel BW: Scalable channel BW to 20 MHz (in contrast with fixed 5 MHz channels for UTRA)
- RAN Latency: 10 ms
The average throughput target requirements for LTE translates to, approximately 1.59 to 2.12 bps/Hz/Sector in the DL for the (2x2) and (4x2) antenna configuration, respectively, and approximately 0.66 to 0.99 bps/Hz/Sector in the UL for the (1x2) and (1x4) antenna configuration, respectively. The LTE requirements also call for a transition to an all-IP core network. This 3GPP initiative is referred to as Evolved Packet Core (EPC).
WiMAX and LTE
The performance projections for LTE most often cited in the public domain assume frequency division duplexing (FDD) with paired 20 MHz channels [Ref 15]. This is despite the fact that current worldwide spectrum allocations sufficient to support paired 20 MHz channels are very limited. To provide a direct comparison of LTE and WiMAX in FDD with paired 20 MHz channels is assumed for both cases. Peak data rates for LTE are usually reported without forward` error correction coding. The LTE peak rates in this table are presented with similar coding as WiMAX to represent a more realistic deployment scenario and to provide a one to one comparison with WiMAX. For reference purposes, the peak theoretical rates without forward error correction coding are also shown for both LTE and WiMAX in italics.
With support for UL collaborative spatial multiplexing, WiMAX achieves 138.2 Mbps for the UL channel data rate. The UL peak user data rate for WiMAX would be 69.1 Mbps.
The performance projections for LTE most often cited in the public domain assume frequency division duplexing (FDD) with paired 20 MHz channels [Ref 15]. This is despite the fact that current worldwide spectrum allocations sufficient to support paired 20 MHz channels are very limited. To provide a direct comparison of LTE and WiMAX in FDD with paired 20 MHz channels is assumed for both cases. Peak data rates for LTE are usually reported without forward` error correction coding. The LTE peak rates in this table are presented with similar coding as WiMAX to represent a more realistic deployment scenario and to provide a one to one comparison with WiMAX. For reference purposes, the peak theoretical rates without forward error correction coding are also shown for both LTE and WiMAX in italics.
With support for UL collaborative spatial multiplexing, WiMAX achieves 138.2 Mbps for the UL channel data rate. The UL peak user data rate for WiMAX would be 69.1 Mbps.
| | LTE | WiMAX Air Interface R1.5 | ||
| Duplex | FDD | FDD | ||
| Channel BW | 2x20 MHz | 2x20 MHz | ||
| BS Antenna | (2x2) MIMO | (2x2) MIMO | ||
| DL Modulation | 64QAM | 64QAM | ||
| DL Coding | 5/6 | 5/6 | ||
| DL Peak Channel Rate | 144.0 Mbps (172.8 Mbps w/o coding) | 144.4 Mbps (173.3 Mbps w/o coding) | ||
| MS Antenna | (1x2) SIMO | (1x2) SIMO | ||
| UL Modulation | 16QAM | 64QAM | 16QAM | 64QAM |
| UL Coding | 3/4 | 5/6 | 3/4 | 5/6 |
| UL Peak Channel Rate | 43.2 Mbps ( 57.6 Mbps w/o coding) | 72.0 Mbps (86.4 Mbps w/o coding) | 82.9 Mbps (110.6 Mbps w/o coding) | 138.2 Mbps (165.8 Mbps w/o coding) |
A summary of the average spectral efficiency comparisons between LTE and WiMAX are provided in Figure 5. Again the LTE values assume FDD with paired 20 MHz channels. To provide a more complete summary, Figure 5 includes several WiMAX deployment options. The WiMAX Air Interface R1.0 TDD profile assumes a 10 MHz channel BW, PUSC permutation for mixed mobility, and a DL to UL ratio of approximately 3:2. This configuration is included to provide a view of what has been commercially available since 2008. The FDD simulation results for WiMAX Air Interface R1.5 are based on paired 20 MHz channels to provide a one-to-one performance comparison to LTE, whereas the TDD Air Interface R1.5 simulation assumes a single 20 MHz channel with a 3:2 DL to UL ratio. Both WiMAX Air Interface R1.5 and LTE meet the average channel spectral efficiency requirements spelled out for LTE in 3GPP Rel-8.
As anticipated, since the underlying technologies for WiMAX and LTE are very similar the key performance parameters, namely peak and average throughput performance are comparable when considered for the same base station and mobile station antenna configurations.
As anticipated, since the underlying technologies for WiMAX and LTE are very similar the key performance parameters, namely peak and average throughput performance are comparable when considered for the same base station and mobile station antenna configurations.
Although the technologies adopted for both WiMAX and LTE have a lot in common there are some differences that are worth noting.
- The reported results for the LTE throughput simulations assume 2000 MHz whereas the WiMAX simulations were done assuming 2500 MHz to reflect performance in the IMT-Extension band, 2500-2690 MHz. This frequency difference will result in a higher path loss for WiMAX as compared to LTE7. Although simulations were not done to accurately quantify the difference between 2000 and 2500 MHz, it is reasonable to expect that this would give LTE a slight advantage in the average spectral efficiency numbers compared to WiMAX.
- LTE uses SC-FDMA, also referred to as DFT-spread OFDM, in the UL, whereas WiMAX uses OFDMA: With SC-FDMA both Fast Fourier Transform and Inverse Fast Fourier Transform are performed in both the receiver and the transmitter. With OFDMA, Fast Fourier Transform is applied on the receiver side and Inverse Fourier Transform on the transmitter side. The single carrier nature of SC-FDMA has thepotential for a lower peak to average power ratio but otherwise provides UL benefits similar to OFDMA.
- LTE frame size is 1 millisecond vs. 5 milliseconds for WiMAX: The smaller frame size may translate to lower latency but at the expense of higher overhead. WiMAX will introduce the concept of sub-frames in WiMAX 2 for latency-sensitive applications.
IMT-Advanced and IEEE 802.16m
IMT-Advanced
IMT-Advanced is the ITU description for systems beyond IMT-2000. ITU Working Group 9 has projected requirements for future systems based on projected demand for mobile services, increased user expectations, and anticipated services and applications that may evolve over the next several years [Ref 16]. Based on these studies IMT-Advanced calls for a shared channel DL peak rate of 1000 Mbps in a low mobility scenario and 100 Mbps in a high mobility situation [Ref. 17, 18]. Low mobility is defined as pedestrian speed (10 km/hr) and high mobility as 350 km/hr. To be considered a candidate access technology, IMT-Advanced spells out minimum performance requirements for the following parameters:
IMT-Advanced is the ITU description for systems beyond IMT-2000. ITU Working Group 9 has projected requirements for future systems based on projected demand for mobile services, increased user expectations, and anticipated services and applications that may evolve over the next several years [Ref 16]. Based on these studies IMT-Advanced calls for a shared channel DL peak rate of 1000 Mbps in a low mobility scenario and 100 Mbps in a high mobility situation [Ref. 17, 18]. Low mobility is defined as pedestrian speed (10 km/hr) and high mobility as 350 km/hr. To be considered a candidate access technology, IMT-Advanced spells out minimum performance requirements for the following parameters:
- Peak and average channel spectral efficiency
- Cell edge user spectral efficiency
- VoIP Capacity
- Control and User Plane Latency
- Handover
- Channel bandwidth
- Mobility
Additional IMT-Advanced requirements address features required for anticipated applications, services, and the expected needs of users and operators; including QoS, roaming, interworking with other wireless networks, etc.
An example of IMT minimum requirements for sector (or channel) spectral efficiency, and concurrent VoIP sessions under various test environments, assuming (4x2) MIMO in the DL and (2x4) MIMO in the UL, is shown in Table 7.
An example of IMT minimum requirements for sector (or channel) spectral efficiency, and concurrent VoIP sessions under various test environments, assuming (4x2) MIMO in the DL and (2x4) MIMO in the UL, is shown in Table 7.
| Test Environment | Speed | DL bps/Hz/Sector | UL bps/Hz/Sector | VoIP Calls/MHz/Sector |
| Indoor | Up to 10 km/hr | 3.0 | 2.25 | 50 |
| Micro-cellular | Up to 30 km/hr | 2.6 | 1.8 | 40 |
| Base Coverage Urban | Up to 120 km/hr | 2.2 | 1.4 | 40 |
| High Speed | Up to 350 km/hr | 1.1 | 0.7 | 30 |
IEEE 802.16m
The IEEE 802.16m project was approved in December 2006 [Ref 19]. The goal of this project is to develop an amendment to the IEEE 802.16 WirelessMAN-OFDMA specification to enable air interface performance in licensed bands that meets or exceeds the requirements of IMT-Advanced. A final specification is scheduled for completion in the early part of 2010 and ratification expected mid 2010.
Key target performance requirements and features for the 802.16m amendment to the IEEE 802.16 Air Interface Standard are summarized in Table 8. Whereas many of the IMT-Advanced minimum performance targets assume (4x2) MIMO in the DL and (2x4) MIMO in the UL, many of the 802.16m numbers are referenced to a baseline configuration of (2x2) MIMO in the DL and (1x2) SIMO in the UL.
The IEEE 802.16m project was approved in December 2006 [Ref 19]. The goal of this project is to develop an amendment to the IEEE 802.16 WirelessMAN-OFDMA specification to enable air interface performance in licensed bands that meets or exceeds the requirements of IMT-Advanced. A final specification is scheduled for completion in the early part of 2010 and ratification expected mid 2010.
Key target performance requirements and features for the 802.16m amendment to the IEEE 802.16 Air Interface Standard are summarized in Table 8. Whereas many of the IMT-Advanced minimum performance targets assume (4x2) MIMO in the DL and (2x4) MIMO in the UL, many of the 802.16m numbers are referenced to a baseline configuration of (2x2) MIMO in the DL and (1x2) SIMO in the UL.
| Parameter | Targeted Performance |
| Frequency Bands | Licensed bands less than 6000 MHz (Typical: 450 MHz to 3800 MHz) |
| Duplex | TDD, FDD, and H-FDD |
| Scalable Channel Bandwidth | 5, 7, 8.75, 10, 20, and 40 MHz |
| Multi-carrier support for contiguous or non-contiguous channels: | Up to 100 MHz operating BW with channel aggregation |
| Increased DL peak channel and user data rate: | >1000 Mbps with low mobility >100 Mbps with high mobility |
| Peak DL Spectral Efficiency | 8.0 bps/Hz with (2x2) MIMO 15.0 bps/Hz with (4x4) MIMO |
| Peak UL Spectral Efficiency | 2.8 bps/Hz with (1x2) SIMO 6.75 bps/Hz with (2x4) MIMO |
| 2x Increase in Average DL Spectral Efficiency with (2x2) MIMO | >2.6 bps/Hz >0.26 bps/Hz per User |
| 2x Increase in cell edge DL user throughput: | >0.09 bps/Hz/User |
| 2x Increase in Average UL Spectral Efficiency with (1x2) SIMO | >1.3 bps/Hz >0.13 bps/Hz/User |
| 2x Increase in cell-edge UL user throughput: | >0.05 bps/Hz/user |
| VoIP Capacity: with (2x2) MIMO in DL and (1x2) SIMO in UL | >30 Concurrent sessions per MHz per sector for AMR 12.2 kbps speech codec |
| Latency | User Plane: < 10 ms UL or DL Control Plane: Idle to Active <100 ms |
| Frame Structure | Super Frame: 20 ms Frame: 5 ms Sub-Frame: 0.625 ms |
| Mobility Support | Up to 500 km/hr |
| Advanced Antenna Systems | DL: (2x2), (2x4), (4x2), (4x4), (8x8) UL: (1x2), (1x4), (2x4), (4x4) |
| Backwards Compatibility | Backwards compatible with WiMAX Air Interface R1.0 and R1.5 |
The proposed frame structure in 802.16m enables tradeoffs between lower latency with the sub-frame structure for latency-sensitive applications and lower overhead with Super Frames for large file transfers.
Other IEEE 802.16m features or performance enhancements to earlier releases include:
Other IEEE 802.16m features or performance enhancements to earlier releases include:
- Single-User and Multi-User MIMO (SU-MIMO and MU-MIMO)
- Multi-Hop Relay Support
- Support for Femto-Cells and Self-Organization (SON)
- Enhanced Multi-Cast and Broadcast Services
- Coexistence and interworking with other Radio Access Technologies
- Multi-Technology Mobile Support
- Enhanced power savings for reduced MS power consumption
WiMAX 2
With the anticipated completion of the IEEE 802.16m specification in 2010, the WiMAX Forum has already begun the development of the WiMAX 2 system profile. By moving forward in concert with the IEEE efforts the WiMAX Forum will be in a position to move very quickly to the certification phase for WiMAX 2 products soon after the ratification of IEEE 802.16m.
WiMAX 2 will provide further enhancements to DL and UL peak user and peak channel data rates. Average channel/sector throughput will also be increased to provide performance that meets or exceeds the IMT-Advanced requirements as outlined for the varied usage models in Table 7.
With the anticipated completion of the IEEE 802.16m specification in 2010, the WiMAX Forum has already begun the development of the WiMAX 2 system profile. By moving forward in concert with the IEEE efforts the WiMAX Forum will be in a position to move very quickly to the certification phase for WiMAX 2 products soon after the ratification of IEEE 802.16m.
WiMAX 2 will provide further enhancements to DL and UL peak user and peak channel data rates. Average channel/sector throughput will also be increased to provide performance that meets or exceeds the IMT-Advanced requirements as outlined for the varied usage models in Table 7.
- WiMAX Migration Path for DL Peak Channel Data Rates
Figure 6 provides a view of the WiMAX migration path for DL peak channel data rate from Air Interface R1.0 through WiMAX 2 with base station antenna configurations of (2x2) and (4x4) MIMO. All of the DL peak values shown in the chart assume 64QAM with a 5/6 code rate and the TDD options assume a DL to UL ratio of 3:2.
With regard to timing, TDD and FDD profiles for WiMAX based on Air Interface R1.5 are anticipated in 2010 and the first certifiable WiMAX 2 products are expected to be available in 2011.
With regard to timing, TDD and FDD profiles for WiMAX based on Air Interface R1.5 are anticipated in 2010 and the first certifiable WiMAX 2 products are expected to be available in 2011.
A TDD option for WiMAX 2 is not shown in the chart but it is possible to extrapolate the expected performance for TDD based on the planned FDD enhancements. With (4x4) MIMO and a 20 MHz channel BW with a 3:2 DL to UL ratio the peak DL data rate for a TDD implementation can be expected to exceed 170 Mbps. Based on these projections for WiMAX 2 with either TDD or FDD, meeting the IMT-Advanced peak DL peak data rate target requirement of 1000 Mbps with (4x4) MIMO would require the aggregation of multiple 20 MHz (or 40 MHz) channels.
- Backwards Compatibility
The requirement for backwards compatibility for WiMAX 2 and other future WiMAX releases will help ensure a graceful migration path for operators that have deployed or will be deploying WiMAX systems. Backwards compatibility ensures the following:
- A WiMAX 2 Mobile Station will interoperate with a WiMAX8 Base Station
- A WiMAX 2 Base Station and a WiMAX Base Station can coexist on the same carrier
- A WiMAX 2 Base Station will support both WiMAX and WiMAX 2 Mobile Stations
- A WiMAX 2 Base Station will support handoff of a WiMAX Mobile Station to or from a WiMAX Base Station or a WiMAX 2 Base Station
- A WiMAX 2 Base Station will efficiently interoperate with a WiMAX Mobile Station
LTE-Advanced
LTE-Advanced is 3GPP’s answer to the IMT-Advanced requirements. Early efforts in developing the LTE-Advanced specification have begun and the standard will be completed as part of 3GPP Rel-10 scheduled for the end of 2010. Since this effort is still in its early phases of development, details have not been fully defined. In any case since it will be based on similar technology in the access network (OFDMA) and the target performance is driven by the same IMT-Advanced requirements, it can be expected that LTE-Advanced and WiMAX 2 will, in the end, have comparable performance with respect to the key air interface metrics.
The major distinction between these two technologies is not going to be with regard to performance but will be with regard to time-to-market (TTM). Depending on exactly when commercial LTE deployments begin; whether it is 2010 or 2011, WiMAX has a 2-3 year TTM advantage in the deployment of a next generation, OFDMA-based, all-IP network.
LTE-Advanced is 3GPP’s answer to the IMT-Advanced requirements. Early efforts in developing the LTE-Advanced specification have begun and the standard will be completed as part of 3GPP Rel-10 scheduled for the end of 2010. Since this effort is still in its early phases of development, details have not been fully defined. In any case since it will be based on similar technology in the access network (OFDMA) and the target performance is driven by the same IMT-Advanced requirements, it can be expected that LTE-Advanced and WiMAX 2 will, in the end, have comparable performance with respect to the key air interface metrics.
The major distinction between these two technologies is not going to be with regard to performance but will be with regard to time-to-market (TTM). Depending on exactly when commercial LTE deployments begin; whether it is 2010 or 2011, WiMAX has a 2-3 year TTM advantage in the deployment of a next generation, OFDMA-based, all-IP network.
Summary and Conclusion
The WiMAX technology is field proven with more than 500 deployments worldwide providing services for fixed, nomadic, portable, and mobile broadband applications. The WiMAX Forum is moving aggressively to define a system specification for WiMAX 2 based on the 802.16m amendment to the IEEE 802.16 Air Interface Standard. This backwards compatible migration path will give operators the capability of meeting IMT-Advanced performance requirements for next generation broadband mobile networks in the 2011/2012 timeframe.
LTE and LTE-Advanced are 3GPP’s response to the IMT-Advanced requirements. LTE which may be available as early as 2010 will have performance comparable to WiMAX with some modest air interface enhancements already approved by the WiMAX Forum with expected availability in 2010. The LTE-Advanced specification, defined by 3GPP Rel-10, is not expected to be finalized until the end of 2010.
Both the 3GPP and WiMAX migration paths are targeting to meet the same end result; the performance goals established by IMT-Advanced. OFDMA with an all-IP core network architecture have been accepted as the basic foundation for achieving these goals.
The WiMAX technology is field proven with more than 500 deployments worldwide providing services for fixed, nomadic, portable, and mobile broadband applications. The WiMAX Forum is moving aggressively to define a system specification for WiMAX 2 based on the 802.16m amendment to the IEEE 802.16 Air Interface Standard. This backwards compatible migration path will give operators the capability of meeting IMT-Advanced performance requirements for next generation broadband mobile networks in the 2011/2012 timeframe.
LTE and LTE-Advanced are 3GPP’s response to the IMT-Advanced requirements. LTE which may be available as early as 2010 will have performance comparable to WiMAX with some modest air interface enhancements already approved by the WiMAX Forum with expected availability in 2010. The LTE-Advanced specification, defined by 3GPP Rel-10, is not expected to be finalized until the end of 2010.
Both the 3GPP and WiMAX migration paths are targeting to meet the same end result; the performance goals established by IMT-Advanced. OFDMA with an all-IP core network architecture have been accepted as the basic foundation for achieving these goals.